December 30, 2009

2009 Non-Small Cell Lung Cancer Staging System (3)

Click the image to view a larger version

As a radiologist, it may be easier to memorize "T" classification based on imaging appearance. The scheme below may be used as a guidance to stage these tumors, however a full text of the New Staging System should be reviewed for comprehensiveness.
  1. Peripheral mass abutting chest wall or diaphragm --- see if there is evidence of invasion of chest wall or diaphragm (T3)
  2. Peripheral mass, distal to lobar bronchus, completely surrounded by lung --- measuring size (less than 3cm = T1, 3-7cm = T2, more than 7cm = T3)
  3. Mass distal to 2 cm from the carina but proximal to lobar bronchus --- T2 by definition
  4. Endobronchial mass: distal to 2 cm from the carina = T2; within 2 cm from the carina = T3
  5. Central mass with postobstructive pneumonitis or atelectasis: lobar or segmental = T2;entire lung = T3
  6. Central mass abutting the mediastinum: invade mediastinal pleura, parietal pericardium = T3; diaphramatic paralysis (phrenic nerve involvement) = T3; invade heart, great vessels, trachea, esophagus, carina, vertebral body = T4
  7. Additional malignant lung nodules: same lobe = T3; ipsilateral different lobe = T4; contralateral = M1a
  8. Malignant pleural effusion or pleural nodule = M1a
Detterbeck FC, Boffa DJ, Tanoue LT. The new lung cancer staging system. Chest 2009:136;260-271.

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December 27, 2009

2009 Non-Small Cell Lung Cancer Staging System (2)

Axial CT images show a large mass (stars) in the left lower lobe with a large left pleural effusion with focal pleural thickening (arrowheads). The lung mass is better seen on a post-thoracentesis image. Transbronchial biopsy revealed adenocarcioma and pleural fluid cytology confirmed the presence of malignant cells. Based on the new staging system, this patient has at least M1a disease.

Based on multiple data sources and available clinical outcome (overall survival), additional schemes to stage NSCLC are implemented in this 7th edition. The subgroups and staging grouping are based on the overall survival as a major determinant. For example, overall survival of patients with "satellite nodule in the same lobe" is similar to those with T3 -- therefore it is classified as T3.

What Have Changed in the New Edition?
  • Additional "satellite nodule in the same lobe" now classified as T3 (previously T4)
  • Additional "satellite nodule in the different ipsilateral lobe" now classified as T4 (previously M1)
  • No change in N staging, but a new node map has been developed to address the issue of boundaries between different nodal stations
  • M staging is now subdivided into M1a and M1b to address significantly different prognosis: "contralateral pulmonary nodule (malignant)" and "pleural dissemination" now classified as M1a; distant metastasis as M1b
Detterbeck FC, Boffa DJ, Tanoue LT. The new lung cancer staging system. Chest 2009;136:260-271.

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December 24, 2009

2009 Non-Small Cell Lung Cancer Staging System (1)

Click the image to view a larger version

The latest (7th edition) version has been accepted by the UICC (Union Internationale Contre le Cancer) and the AJCC (American Joint Committee on Cancer) and was published earlier this year.

Non-Small Cell Lung Cancer (NSCLC) Staging System
  • Based solely on anatomic extent of disease (clinical symptoms or molecular behavior of tumors not included)
  • T = tumor; increasing T meaning larger tumor or invasive into more peripheral or central structures
  • N = lymph node location (not number)
  • M = metastasis
  • Two methods of staging = clinical (c) and pathological (p); clinical staging includes all information available PRIOR to any treatment (including invasive staging technique); pathological staging include information AFTER a resection
Sources of Data for the 7th Edition
  • 81,015 included cases from 45 sources in 20 countries
  • Only NSCLC included
  • Major determinant is the overall survival
Detterbeck FC, Boffa DJ, Tanoue LT. The new lung cancer staging system. Chest 2009;136:260-271.

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December 21, 2009

Peer Review in Radiology (2)

Scoring Language for Peer Review

By the American College of Radiology's RADPEER
  1. Score 1 = concur with interpretation
  2. Score 2 = discrepancy in interpretation/not ordinarily expected to be made (understandable miss)
  3. Score 3 = discrepancy in interpretation/should be made most of the time
  4. Score 4 = discrepancy in interpretation/should be made almost every time - misinterpretation of finding

How These Could Be Utilized?

  • For individual radiologists: maintenance of certification, ongoing quality improvement in diagnostic accuracy, opportunity for education
  • For institution: monitoring of radiologist performance as an individual and a group, tracking data over time, monitoring trends, conforming with requirements of several controlling agencies

Ideal Peer Review
  • Reveals opportunity for quality improvement
  • Ensures radiologist competence
  • Improves individual radiologist outcome
  • Should be unbiased, fair, balanced, timely, ongoing and nonpunitive
  • Should allow easy participation
  • Should have minimal effect on work flow
The most popular system in use at present is the American College eRADPEER

Mahgerefteh S, Kruskal JB, Yam CS, et al. Peer review in diagnostic radiology: current state and a vision for the future. Radiographics 2009;29:1221-1231.
2. Jackson VP, Cushing T, Abujudeh HH, et al. RADPEER scoring white paper. J Am Coll Radiol 2009;6:21-25.

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December 18, 2009

Posterior Acoustic Features of Breast Mass

Transverse ultrasound image of the breast shows an irregularly shaped hypoechoic mass (between calipers) with posterior attenuation of the acoustic transmission ("shadowing"). The shadowing obscures the posterior margin of the mass.

Posterior Acoustic Features
  • Attenuation characteristics of a mass with respect to its acoustic transmission
  • Four patterns: no posterior acoustic features, enhancement, shadowing and combined
Posterior Shadowing
  • Attenuation of sound beam deeper to a mass
  • Associated with fibrosis, with or without underlying carcinoma
  • DDx: scars, fibrous mastopathy and cancer with desmoplastic response
  • Helpful feature when present (suggesting above diagnoses)
  • Should be distinguished from "refraction or edge shadowing" which is a thin shadow seen at the edges of curved masses that is of no significance
Our case: invasive ductal carcinoma

Madjar H, Mendelson EB. The practice of breast ultrasound, 2nd edition, 2008.

December 15, 2009

Insall-Salvati Ratio for Assessment of Patella Height

Lateral view of the knee shows a method of measuring patella height in this patient who fell and was unable to extend the knee.

Facts: Insall-Salvati Method
  • Patella height expressed as a ratio of patellar tendon length (LT) to greatest diagonal length of the patella (LP)
  • Most commonly used method to assess patellar height in all degrees of flexion
  • LT = length of tendon = tendon origin at inferior patella to its insertion at the tibial tubercle
  • LP = length of patella = diagonal length of the patella
  • Normal = LT roughly is equal to LP, any variation more than 20% considered abnormal
  • LT:LP more than 1.2 = patella alta
  • LT:LP less than 0.8 = patella infera

Our case: LT:LP is greater than 2, this is patella alta due to traumatic complete patellar tendon rupture.

Scuderi GR. The Patella, 1995.

December 12, 2009

Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Figure 1: Baseline chest radiograph of a patient with known idiopathic pulmonary fibrosis (IPF) shows bibasilar coarse reticular opacities, traction bronchiectasis and subpleural opacities.
Figure 2: Chest radiograph performed 3 months later when the patient developed acute dyspnea and hypoxemia shows new groundglass opacities superimposed on areas of pre-existing IPF.

Facts: IPF
  • Most common form of idiopathic interstitial pneumonias
  • Gradually progressive disease with steady worsening of symptoms, lung function and gas exchange
  • Median survival 3 years, no current treatment proven effective
Facts: Acute Exacerbation of IPF
  • Some patients with IPF develops acute respiratory deterioration, which is an unusual natural course of diseases
  • Idiopathic, no identifiable cause (infection, heart failure or pulmonary embolism)
  • This can occur at anytime during the disease course, and can be a presenting symptom of IPF
  • More common in men
  • Acute to subacute worsening of dyspnea, generally within 30 days, fever, cough, flulike symptoms, severe hypoxemia, respiratory failure requiring mechanical ventilation, low PaO2/FiO2 ratio
Imaging Features
  • Bilateral groundglass opacities with or without consolidation, superimposed on pre-existing IPF
  • Groundglass opacities can be peripheral, multifocal or diffuse (pathology from surgical lung biopsy usually shows diffuse alveolar damage)
  • Differential diagnosis on imaging: pulmonary edema, pneumonia superimposed on IPF
Diagnostic Criteria
  • Previous or concurrent diagnosis of IPF
  • Unexplained worsening or development of dyspnea within 30 days
  • HRCT with new bilateral groundglass abnormality and/or consolidation superimposed on a background reticular or honeycomb patter consistent with IPF
  • No evidence of pulmonary infection by endotracheal aspirate or bronchoalveolar lavage
  • Exclusion of alternative causes, including the following: left heart failure, PE, identifiable cause of acute lung injury
Collard HR, Moore BB, Flaherty KR, et al. Acute exacerbations of idiopathic pulmonary fibrosis. Am J Respir Crit Care Med 2007;176:636-643.

December 9, 2009


Figure 1: Lateral chest radiograph of a 76-year-old man with back pain shows destruction of mid-thoracic disc space (star).
Figure 2: Sagittal reformatted CT image (myelogram) shows destruction (star) of the disk space, opposing endplates and epidural extension of soft tissue (arrowheads) seen as filling defect on this myelographic study.

Facts: Spinal Infections
  • A spectrum of diseases - osteomyelitis (spondylitis), discitis, discitis-osteomyelitis, epidural abscess
  • Of all osteomyelitis, spine accounts for 2% - 4% of anatomic sites
  • When spinal infection involves thoracic spine, neurologic compromise is a concern
  • Patients at risk include diabetes, IV drug user, chronic delibitating disease, immunosuppression, recent vertebral surgery
  • Most common clinical presentation = axial back pain, constant, not relieved by rest (night pain is a red flag for infection or neoplasm)
  • Most spinal infections are due to bacterial infection (>50%, S. aureus); definitive diagnosis made by culture from blood or biopsy

  • Plain radiography: disc space narrowing (2-3 weeks of infection) --> endplate sclerosis (8-12 weeks) --> bony lysis --> vertebral body collapse resulting in localized kyphosis
  • CT: more bony details, with myelography it can delineate the degree of spinal canal encroachment
  • MRI: best imaging method to assess spinal infection; high sensitivity/specificity/accuracy (more than 90%)
  • Features: disc destruction (narrowing, signal change), endplate destruction, abscess, epidural extension, posterior element involvement
  • Think of TB if: late clinical presentation, extensive paravertebral abscess, relative preservation of disc, subligamentous spread
Our case: Discitis-osteomyelitis from Staphylococcus aureus.

1. An HS, Seldomridge JA. Spinal infections diagnostic tests and imaging studies. Clin Orthop Rel Res 2006;444:27-33

December 8, 2009

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Above picture: Singapore's Flyer by Paithoon Wichiwaniwate, M.D.

December 6, 2009

Zygomaticomaxillary Complex (ZMC) Fracture

Figures 1 & 2: Axial CT images show displaced fractures of the anterior and posterior walls of the right maxillary sinus (arrows), subtle fracture of the right zygomatic arch (short arrow) and a slightly angulated fracture of the lateral wall of the orbit (arrowhead).
Figure 3: 3D CT image shows a complete look of a ZMC fracture, including the fracture of the maxillary walls, zygomatic arch (arrow) and lateral orbital wall at the zygomaticosphenoid suture (arrowheads).

Facts: ZMC Anatomy
  • The zygomaticomaxillary complex is a quadrupled structure, meaning that it relates to 4 different bones of the skull: temporal bone, maxilla, frontal bone and skull base
  • Paired zygomas each have two attachments to the cranium and two to the maxilla.
  • Two major 'buttresses' of the ZMC are: upper transverse maxillary (across zygomaticomaxillary and zygomaticotemporal sutures) and lateral vertical maxillary (across zygomaticomaxillary and zygomaticofrontal sutures).
  • In fact, zygoma also relates posteriorly with the sphenoid bone of the skull base
Facts: ZMC Fractures
  • Fractures involving this quadrupled structures: anterior maxillary wall, posterolateral maxillary wall, zygomatic arch and lateral orbital wall
  • If fracture at the lateral orbital wall is angulated, it often increases orbital volume resulting in enophthalmos)
  • If fracture at the zygoma is comminuted, it often requires fixation via a scalp incision to fix the loss of cheek projection and increase facial width
  • Frequently missed ZMC fracture is at the temporal bone portion
Imaging Descriptions
  • Describe alignment of the zygoma and sphenoid at the lateral orbital wall fracture; angulation here reflects rotation deformity and increased orbital volume that needs to be fixed
  • Describe if the fracture along the zygomaticomaxillary suture traverses the infraorbital nerve foramen
  • Degree of comminution of zygomatic arch
  • Don't forget to look at the temporal bone portion of the ZMC for a fracture
Hopper RA, Salemy S, Sze RW. Diagnosis of midface fractures with CT: what the surgeon needs to know. Radiographics 2006;26:783-793.

December 3, 2009

H1N1 (Swine Flu) Pneumonia

Chest radiograph shows patchy airspace opacities in bilateral mid to lower lung zones in a patient infected with H1N1 virus (lab confirmed), admitted to the ICU. Subsequent CT (not shown) reveals similar findings without pleural effusions or lymphadenopathy.

  • First reported in Mexico in April 2009
  • Fatality rate 0.45%
  • Confirmed case = a person with an influenza-like illness with laboratory confirmed novel influenza A (H1N1) virus infection by one or more of the following tests: real-time RT-PCR, viral culture
  • Influenza-like symptoms = fever, cough, sore throat, body aches, headache, chills, fatigue
Radiographic Appearance
  • Initial exam is normal in nearly half of cases who had radiography
  • When initial exam is abnormal, the abnormality is patchy consolidation (50%), groundglass opacity or groundglass opacity with consolidation (25%)
  • Predominant location: lower lung zones (70%), diffuse (25%)
  • Pleural effusion not common (less than 10%)
  • Lymphadenopathy uncommon
Based on a single, uncontrolled study:
  • Patients with abnormal initial radiograph were associated with admission and severe disease
  • H1N1 infection was associated with a high rate of pulmonary embolism (36%) among patients admitted to the ICU

Agarwal PP, Cinti S, Kazerooni EA. Chest radiographic and CT findings in novel swine-origin influenza A (H1N1) virus (S-OIV) infection. AJR 2009;193:1488-1493.

November 30, 2009

Nonvisualization of the Gallbladder with HIDA Scan

HIDA (Tc-99m hydroxy iminodiacetic acid) scan shows normal uptake in the liver with excretion into the extrahepatic bile duct (arrow) and in the bowel (arrowheads) at 25-30 minutes after radiotracer injection. Intravenous morphine was administered at 60 minutes. The images obtained up to 2 hours show no activity in the gallbladder.

Facts: HIDA scan
  • Also known as hepatobiliary scan
  • Liver uptakes HIDA and excretes it into bile that drains into the bowel
  • Normal activity should be seen immediately in the liver, at one hour in gallbladder and into the bowel
  • The scan can be done to help diagnose acute cholecystitis, postoperative bile leak
  • Morphine can be utilized to shorten the examination time for the diagnosis of acute cholecystitis if the gallbladder is not seen at 1 hour but the bile duct and bowel activity is visualized.
  • Cholecystokinin or fatty meal can be used to help diagnose chronic cholecystitis.

Findings on HIDA scan
Nonvisualization of gallbladder WITH bowel activity
  • Acute cholecystitis
  • Previous cholecystectomy
  • Non-fasting patient (including IV feeding)
  • Severe hepatic disease
  • Chronic cholecystitis (usually fills after 1 hour)
Nonvisualization of gallbladder WITHOUT bowel activity
  • Biliary obstruction of any cause
  • Severe hepatic disease
  • Opiates (because of their effect on the sphinctor of Oddi)
Our patient: acute cholecystitis confirmed at surgery

1. Sharp PF, Gemmell HG, Murray AD. Practical nuclear medicine, 3rd edition, 2005.
2. Chapman S, Nakielny R. Aids to radiological differential diagnosis, 4th edition, 2003

November 27, 2009

Popliteal Artery Aneurysm

Figure 1: Gray-scale ultrasound of the let popliteal ultrasound shows a fusiform aneurysm of the popliteal artery, measuring 2 cm.
Figure 2: Color Doppler US image shows partial thrombosis of the aneurysm.

  • Most common peripheral artery aneurysm
  • Most commonly due to atherosclerosis
  • More common in male
  • Commonly bilateral (need to examine the contralateral popliteal artery), and commonly associated with abdominal aortic and iliac artery aneurysm in about half of all cases.
  • Presentation: cold lower extremity from acute thrombosis or distal embolization, asymptomatic pulsatile popliteal fossa mass, rarely rupture
Indication for Repair
  1. Size 2 cm or greater
  2. Intraluminal thrombus

Imaging Strategy
  • Doppler US for diagnosis and follow up
  • MDCT for planning of repair (surgical or endovascular): extent, location of associated peripheral vascular disease, nearby branch vessels, size and angulation of the aneurysm
1. Blackbourne LH. Surgical recall, 5th ed, 2008.
2. Funaki B, Lorenz J, Ha TV. Teaching atlas of vascular and non-vascular interventional radiology, 2007.

November 24, 2009

An Expert's Response to the Recent USPSTF Recommendations for Mammography

A recent release of the US Preventive Services Task Force (USPSTF) recommendations for breast cancer screening has brought about so many controversies. Below is the summary view of Dr. Daniel B. Kopans, a Mass General radiologist and Harvard professor, internationally known as a breast imaging expert:

Mass General Imaging believes that the USPSTF recommendations are based on flawed analysis of the data and continues to support the scientifically based recommendations of the American Cancer Society for the early detection of breast cancer:

  1. Annual mammographic screening should begin at age 40
  2. Women at high risk for developing breast cancer should have annual MRI screening in addition to mammography

View full article by Dr. Kopans (MGH Radiology Rounds) HERE
Read more controversies in the New York Times and Washington Post
Read where the American College of Radiology stands

Additional opinions from the New England Journal of Medicine (November 25, 2009)
- Screening mammography and the "R" word
- On mammography - more agreement than disagreement

November 21, 2009

New Guidelines for Cervical Cytology Screening Released

The American College of Obstetricians and Gynecologists (ACOG) released its new clinical management guidelines for cervical cytology screening today.

New Recommendations
  • Screening should begin at age 21 years (previously at the age of first sexual intercourse)
  • Frequency of screening: every two years for women aged 21-29 years; for women aged 30 and older -- if results have been negative for intraepithelial lesions and malignancy for three times they may be screened at every three years
  • More frequent screening may be done in high-risk groups including: HIV infection, immunosuppression, exposure to diethylstilbestrol in utero, previously treated for CIN2, CIN3 or cancer
  • Discontinue screening: at either 65 or 70 years in women with three or more negative cytology test results in a row and no abnormal results in the past 10 years; immediately after total hysterectomy for benign indications and no prior history of high-grade CIN
  • Both liquid-based and conventional methods for cervical cytology are acceptable for screening
  • Co-testing with a combination of cytology and HPV DNA testing: appropriate for women older than 30 years.

November 18, 2009

Updated Recommendation for Breast Cancer Screening

The update of the U.S. Preventive Services Task Force (USPSTF) recommendation statement on screening for breast cancer in the general population has been published today in the Annals of Internal Medicine.

The USPSTF Recommends
  • Against routine screening mammography in women aged 40-49 years
  • Biennial (every two years) screening mammography for women between the ages of 50 and 74 years
Based on the USPSTF review, the current evidence is insufficient to assess benefits and harms of ...
  • Screening mammography in women 75 years or older
  • Clinical breast examination beyond screening mammography in women 40 years or older
  • Either digital mammography or magnetic resonance imaging instead of film mammography as screening modalities for breast cancer
What Has Changed from the Previous Recommendations, and Why?
  • Recommendations against universal screening mammography for women aged 40 to 49 years, based in part on an updated systematic review of screening mammography randomized, controlled trials that showed lower yield of reduced breast cancer mortality and higher false-postive results with screening in this population
  • Recommendation of biennial screening mammography for women aged 50 to 69. Based on statistical models, annual versus biennial screening showed similar degree of breast cancer mortality reduction and similar likelihood of late-stage disease at diagnosis.
  • Extension of screening mammography to women aged 70 to 74 years. Models estimate that approximately 2 additional breast cancer deaths are averted per 1000 women screen at this age.
Read full text here (free)

1. U.S. Preventive Services Task Force. Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2009;151:716-726.
2. Kerlikokowske K. Evidence-based breast cancer prevention: the importance of individual risk. Ann Intern Med 2009;151:750-752.

November 15, 2009

Os Terminale - Os Odontoideum Complex (3)

A sagittal-reformated CT image shows a characteristic appearance of os odontoideum (O). Note a wide gap between the os and the hypoplastic dens (D). The anterior arch of C1 (A) is hypertrophied.

Facts: Os Odontoideum
  • Ossicle either in a normal odontoid tip (orthotopic) or near basi-occiput (dystrophic)
  • Often fixed to the anterior C1 ring and the two move as a single unit
  • Often asymptomatic (found incidentally) but some patients may have symptoms of C1-2 instability or at risk of developing cord injury following severe trauma
Imaging Features
  • Smooth, small or large ossicle, can be rounded or oval or very bizarre and irregular in shape
  • Hypoplastic dens. Wide gap between the os and dens
  • Anterior arch of C1 is hypertrophied
  • Jigsaw sign (a narrow joint space between the anterior C1 arch and the os, and an interdigitating joint line)
Differentiation of Unstable Os Odontoideum from Ununited Dens Fracture
  • In ununited dens fracture, the dens is normal in size and configuration but there is nonunion through the base of the dens. Nonunited fragment becomes hypermobile and behave like an os odontoideum. However, either of this would need surgical stabilization
Clinical Implication
  • The whole complex is variably unstable; therefore superimposed cervical spine trauma can make it more unstable and even can lead to acute cord injury
  • Suggest instability if 1) forward flexion of C1 on C2 more than 2 mm on flexion view, or 2) the os is posterior to its normal location
1. Fagan AB, Askin GN, Earwaker JWS. The jigsaw sign. A reliable indicator of congenital aetiology in os odontoideum. Eur Spine J 2004;13:295-300.
2. Truumees E. Os odontoideum. E-medicine, updated September 12, 2008.
3. Swischuk L. Imaging of cervical spine in children, 2004.

November 12, 2009

Os Terminale - Os Odontoideum Complex (2)

Sagittal reformatted CT image shows an os terminale, sitting on top of the normal-sized dens.

Os Terminale
  • Derived from the 4th occipital sclerotome but does not undergo fusion with the dens
  • The dens is normal in size and shape
  • If it enlarges, coupled with dens hypoplasia -- it is called os odontoideum
  • Usually single, smooth
  • Sometimes can show bony fragmentation mimicking a comminuted fracture (but one should be aware that an extensively comminuted fracture at the tip of the dens is extremely rare or nonexistent)
Swischuk L. Imaging of the cervical spine in children, 2004.

November 9, 2009

Os Terminale - Os Odontoideum Complex (1)

Diagram showing a range of dens anomalies from normal, os terminale and os odontoideum (hypoplastic dens). Adapted from Reference #1.

"I have always considered them [os terminale and os odontoideum] to be the same, believing that the os terminale becomes the os odontoideum when it enlarges in association with hypoplasia of the dens." - Leonard Swischuk, MD

Development of os terminale/os odontoideum complex
  • Os terminale is derived from the 4th occipital sclerotome
  • Os terminale develops and then fuses with the dens in most cases (becoming the tip of the dens)
  • If the os terminale does not fuse with the dens, it can overgrow and become the os odontoideum while the dens becomes hypoplasia. At the same time C1-2 stabilizing ligaments will be underdeveloped and predispose this section to hypermobility and instability
Imaging Appearance
  • Both os terminale and os odontoideum typically is a single, smooth ossicle
  • Sometimes, they can show bony fragmentation, bizarre and irregular in shape
  • If found posterior to its normal location, one can presume that there is some degree of instability
  • Anterior arch of C1 can overgrow (hyperplastic); this does not suggest that there is ununited fracture of the dens
1. Swischuk L. Imaging of the cervical spine in children, 2004.

November 6, 2009

Totally Accessible MRI: A User's Guide to Principles, Technology, and Applications

Book title: Totally Accessible MRI: A User's Guide to Principles, Technology, and Applications
Cover type: Soft cover
Name of author: Michael L. Lipton, MD, PhD
Number of pages: 313
Publisher: Springer
City and state of publication: New York, USA
Year of publication: 2008

Totally Accessible MRI is an outgrowth of more than a decade of experience of Dr. Michael L. Lipton, MD, PhD, in teaching magnetic resonance imaging (MRI) course at the Albert Einstein Medical College in New York. It is intended to anyone who has interest to understand MRI as it is used in clinical imaging and its behind-the-scene physics.........

Continue reading the review at this link (hosted by

November 3, 2009

Choroid Plexus Mass

Figure 1: Axial T2 MR image of the brain of a 24-year-old man shows a heterogeneous mass (arrows) in the temporal horn of the right lateral ventricle. Note a CSF cleft (arrowhead) anterolateral to the mass and low T2 signal intensity within the mass. There is no edema of the adjacent brain parenchyma.
Figure 2: Axial T1 post-contrast image shows homogeneous enhancement of the mass.

Facts: Choroid Plexus
  • Starts differentiating in week 6 and has an adult appearance by week 20 of gestation
  • Choroid plexus epithelium + capillaries are lined by ependymal cells. Capillaries are fenestrated allowing free movement of small molecules (lack of blood brain barrier), but epithelial cells connect each other with tight junction preventing passage of most macromolecules into CSF.
  • Forms CSF and actively regulates CSF constituents
Choroid Plexus Mass
  • Choroid plexus papillomas and carcinomas are common in young children (under 5 years old)
  • Papillomas are benign tumor arising from choroidal epithelial cells; 5%-10% degenerate into carcinomas
  • Papillomas are common in the first year of life, boys > girls, usually presenting with hydrocephalus (due to either CSF overproduction or obstruction in subarachnoid/intraventricular CSF pathways)
Imaging Findings: Choroid Plexus Papilloma
  • Lobulated intraventricular mass; 25% calcified
  • Isoattenuation on non-contrast CT
  • Homogeneously enhanced after IV contrast administration
  • On T2W MR image, central hypointensity is characteristic
  • "Aggressive" papillomas may show irregular margins and grow into adjacent white matter causing edema
Suspect Choroid Plexus Carcinomas When:
  • Presents with focal neurological deficits
  • Grows into adjacent brain parenchyma, causing vasogenic edema
  • Metastasize through CSF

Our case: choroid plexus papilloma in a young adult. Given our patient's age, differential diagnosis of meningioma, lymphoma and metastasis should also be entertained.


Naeini RM, Yoo JH, Hunter JV. Spectrum of choroid plexus lesions in children. AJR 2009;192:32-40

October 30, 2009

FDG-PET and Multiple Myeloma

Figure 1: A radiograph of the right humerus (a part of skeletal survey) shows no abnormality in a 69-year-old man recently diagnosed with multiple myeloma.
Figure 2: FDG-PET shows multiple areas of hypermetabolism, including in the right humerus where the radiograph was negative. The majority of lesions in the ribs, scapulae and spine are not visualized on the skeletal survey.

Facts: Multiple Myeloma Staging (Durie-Salmon system)
  • Based on 4 factors: Hemoglobin, serum calcium, x-ray abnormality and amount of abnormal monoclonal immunoglobulin in blood or urine
  • Stage I: slightly decreased Hb, normal serum Ca, normal x-ray or only one area of bone damage, relatively small monoclonal immunoglobulin
  • Stage II: between I and III
  • Stage III: Hb <> 12 mg/dL, three or more areas of bone damage, large amount of monoclonal immunoglobulin
Multiple Myeloma Imaging Staging
  • Staging and monitoring is very important to management decision.
  • Studies of the National Oncologic PET Registry with 1300 myeloma patients showed that 36.5% of the time, treating physicians changed the intended management on the basis of PET/CT results
  • Traditional radiologic staging is to use skeletal survey but it can underestimate extent and magnitude of disease. Bone scan and gallium scan are unreliable.
  • Whole-body MRI has been used but it can be difficult to differentiate active disease from scar tissue, necrosis, fracture or benign disease
  • Several studies performed to assess the utility of FDG PET in staging and monitoring of multiple myeloma: they found that FDG PET is useful and superior to radiography in staging of newly diagnosed non-secretory myeloma (PET can upstage disease, can show bone/bone marrow abnormality in the absence of radiographic bone damage, can show sites of extramedullary disease), restaging and monitoring of non-secretory myeloma
  • FDG PET also can help differentiating multiple myeloma from monoclonal gammopathy of uncertain significance (MGUS)
FDG-PET has recently been approved for reimbursement by the U.S. Medicare & Medicaid Services.

1. Durie BGM, Waxman AD, D'Agnolo A, Williams CM. Whole-body 18-F-FDG PET identifies high-risk myeloma. J Nucl Med 2002;43:1457-1463
2. Dimopoulos M, Moulopoulos LA, Terpos E. A new pet for myeloma. Blood 2009;114:2007-2008.
3. The American Cancer Society. How is multiple myeloma staged? Link

October 27, 2009

Double Aortic Arch

A scout CT image of a 70-year-old woman shows subtle prominence of the right paratracheal soft tissue. There is slight narrowing the trachea at the level of the left aortic arch. The patient also has a large hiatal hernia.
Coronal reformatted CT image shows a double aortic arch, in which the right-sided arch is approximately about the same size as the left.

Facts: Double Aortic Arch
  • Most common symptomatic vascular ring
  • Ascending aorta divides anterior to the trachea into left and right arches; right arch typically is larger and more superiorly located than the left arch and passes posterior to the esophagus joining the descending aorta
  • Complete ring around trachea and esophagus may cause compression
  • Usually not associated with congenital heart disease (if it is, tetralogy of Fallot predominates)
  • Rarely presents in adulthood (as in our case)
  • Diagnosis often suggests by the presence of right sided aortic arch on radiography
  • Barium esophagography shows bilateral indentations of the esophagus in AP view
  • CT and MRI confirms the diagnosis. The size of each arch, degree of atresia (if present), branching patterns and degree of compression should be reported.

1. McMillan JA, et al. Oski's pediatrics: principles & practice, 4th ed, 2006.
2. Moss AJ, et al. Moss and Adam's heart disease in infants, children, and adolescents, 7th ed, 2007.

October 24, 2009

Buckle (Torus) Fracture of the Distal Forearm

Radiographs of the wrist of an 11-year-old girl following a fall show a subtle buckle fracture of the distal radius (arrows), clearly visible on the lateral view.

  • Common locations = wrist and ankle
  • 2nd most common fractures in infancy and childhood after epiphyseal-metaphyseal fractures
  • Falls on outstretched extremity

Imaging Features:
  • Rule -- cortex of a normal bone is always smooth and gently curving (always trace each cortex individually in all available views)
  • Buckle fractures can be a focal cortical slope, angle, kink, bump or break
  • Usually clearly visible on one view than another
  • When healed, sclerosis develops along the fracture line

1. Swischuk LE. Emergency imaging of the acutely ill or injured child. 4th ed, 2000.

2. Swischuk LE. Imaging of the newborn, infant, and young child. 5th ed, 2004.

October 21, 2009

Tubo-ovarian Abscess

Axial CT image of a young woman with left pelvic pain shows an enhancing, thick walled fluid collection in the left adnexa (arrows) inseparable from the left ovary. The right ovary is marked with an arrowhead.

Facts: Pelvic Inflammatory Disease
  • Young, sexually active, reproductive-aged women
  • Chlamydia trachomatis, Neisseria gonorrhoeae are the most common causative organisms
  • Risk factors include sexual activity at a younger age, several sexual partners, nonuse of barrier contraception
  • Complications include tubo-ovarian abscess (TOA; up to 30% of hospitalized patients with PID), perihepatitis
Clinical Diagnosis of PID
Abdominal tenderness, cervical motion tenderness and bilateral adnexal tenderness with at least one minor diagnostic criteria:
  • Documented cervical infection with C trachomatis or N gonorrhoeae
  • Mucopurulent cervicitis
  • Temperature > 38.3 C
  • Elevated erythrocyte sedimentation rate or C-reactive protein
  • Presence of an inflammatory mass on pelvic sonography
Imaging of TOA
  • Mass inseparable from the tube and ovary
  • Complex mass, fluid attenuation, thickened and irregular enhancing wall
  • Anterior displacement of the broad ligament may allow differentiation from pelvic abscesses from other sources (i.e. appendix, colon)
1. Lareau SM, Beigi RH. Pelvic inflammatory disease and tubo-ovarian abscess. Infect Dis Clin N Am 2008;22:693-708.

2. Potter AW, Chandrasekhar CA. US and CT evaluation of acute pelvic pain of gynecologic origin in nonpregnant premenopausal patients. Radiographics 2008;28:1645-1659.

October 18, 2009

Peer Review in Radiology (1)

What is Peer Review?

  • Most common method to assess performance of medical and clinical knowledge among radiologists
  • An assessment of adherence to standard of care of radiologists, typically involve diagnostic accuracy
  • Degree of interpretative agreement between radiologists is often used (perceived diagnostic features, correct interpretation and reporting)
Why Peer Review?
  • Ongoing quality assurance of diagnostic accuracy is important in radiology
  • It is also one of several crucial aspects in the maintenance of certification
  • It may ensure adherence to standard of care within an institution
  • It helps identifying opportunities for additional education, error reduction and self improvement
How to Peer Review?
  • In general, there are two methods: proactive or reactive
  • Proactive is to assign routine double reading of imaging studies by separate radiologists and compare the results
  • Reactive is by using discrepancy reporting, or by re-reviewing a previously read study during routine interpretation of a current study to evaluate the previous radiologist's interpretation.
  • Scoring is given for different degrees of discrepancy

Mahgerefteh S, Kruskal JB, Yam CS, et al. Peer review in diagnostic radiology: current state and a vision for the future. Radiographics 2009;29:1221-1231.

October 15, 2009

Climate Change and A Radiologist

Since today is a Blog Action Day and the theme of this year is 'Climate Change', we at are requested to discuss about this topic. If you happen to visit any other blogs today, you probably will notice that everyone is talking about the climate change. Don't get bored yet, it is only a day.

How did I get materials for today's post? I began by googling 'radiologist green' and found several links of Drs. Green who are radiologists. I won't blame google for this and won't try Bing (because it's not google) either. I changed my keywords to 'radiologist climate change'. The article in Radiology Business Journal came up "The Invisible Radiologist Meets the New Math, Climate Change and Business 101". You can click the link to view the full online article; it talks about the medical/radiologic climate change with a new healthcare bill on its way to change the face of healthcare in the United States. I'm sorry I'm not going to touch on this.

Let's get back to our business, what do you do - as a radiologist - to make the world around you greener? Here are my suggestions. [please note that these are not professional recommendations by any means]
  • Change to digital imaging (filmless environment helps keep our planet green, no more printing!)
  • Dimming the light in the reading rooms (less energy consumption, also following a good practice)
  • Image more appropriately (picking the right examination for the right clinical question) and less frequently
  • Give less radiation to our patients (also saving energy consumption of CT scanners)
You are welcome to add your thoughts in the comment section below.

Have a good day! team

October 12, 2009

Nuss Procedure for Pectus Excavatum

PA and lateral chest radiographs show a retrosternal Nuss bar in a patient following Nuss procedure. Note the retrosternal location (arrow) and the intercostal attachments (arrowheads) of the bar.

Facts: Nuss Procedure
  • New approach to repair pectus excavatum
  • Simple technique with better cosmetic results; aiming to elevate the deepest part of the depression
  • Done by placing a retrosternal metallic bar through small incisions in the intercostal space. The bar penetrates the pleural cavity at the hinge point at either side.
  • Several types of bars available to choose depending on the morphology of pectus excavatum
  • It is important for surgeon to elevate the deepest part of the depression, which is not necessarily the center of the sternum!
  • Most common = pneumothorax
  • Followed by: bar displacement, seroma, pleural effusion, pericardial effusion
  • Bar displacement can be: 1) flipping (most common), 2) lateral sliding, 3) backward shift
Park et al. The Nuss procedure for pectus excavatum: evolution of techniques and early results on 322 patients. Ann Thorac Surg 2004;77:289-295.

October 11, 2009

Updated ACR Appropriateness Criteria

The American College of Radiology (ACR) Appropriateness Criteria has recently been updated and published online on September 30, 2009.

The "Appropriateness Criteria" is evidence-based guidelines for physicians and providers to help making the most appropriate imaging or treatment decision for a given clinical condition. This latest release include 167 topics with over 800 variants addressing various radiology subspecialty, including radiation oncology.

Click here to go to the ACR Appropriateness Criteria page.

October 9, 2009

Pectus Excavatum

An axial CT image shows a measurement of Haller index (A = transverse diameter, B = anteroposterior diameter of the inner chest wall), which is approximately 3.4 indicating severe pectus excavatum.

Facts: Pectus Excavatum
  • Congenital chest wall deformity "caved-in" or concave appearance in the anterior chest wall
  • Most common type of congenital chest wall deformity (90% of all), followed by pectus carinatum (approximately 5%)
  • Most cases are diagnosed within the first year of life
  • Worsening during rapid bone growth (early teenage)

  • Easy to make on a clinical ground
  • Radiography and chest CT performed to determine the need of surgery, and for surgical planning
  • Haller index is used to grade the severity (Haller index = transverse chest diameter divided by anteroposterior diameter)
  • Haller index > 3.2 correlates with severe deformity that requires surgery
  • Two morphologic classifications of pectus excavatum: 1) symmetric (center of the sternum is the same as the center of depression 2) asymmetric (center of the depression is off to one side i.e. not at the same location as the center of the sternum). Chest CT is best used to show the morphology and for surgical planning
1. Park HJ, Lee SY, Lee CS, et al. The Nuss procedure for pectus excavatum: evolution of techniques and early results on 322 patients. Ann Thorac Surg 2004;77:289-295.
2. Hebra A. Pectus excavatum. In: E-medicine, updated Sep 21, 2009.

October 6, 2009

Retroperitoneal Lymphadenopathy

Axial and coronal reformatted CT images show bulky retroperitoneal lymph nodes (arrows) and mesenteric lymph nodes (arrowheads). The lymph nodes are homogeneously enhanced and appear to surround the vessels.

Facts: Retroperitoneal Lymphadenopathy
  • Diagnosed on CT or MRI by nodal enlargement that may be accompanied by displacement of adjacent structures
  • Upper limit of normal at this location = 10 mm
  • 8-10 "multiple" lymph nodes should be viewed with suspicion
  • Large differential possibilities, including infection/inflammation and neoplasm.
  • Generally, benign conditions do not exhibit massive conglomeration of lymph nodes
Differential Diagnosis:
  • Infection: TB, MAI
  • Inflammation: sarcoidosis, Castleman disease, bulky form of retroperitoneal fibrosis
  • Neoplasm: lymphoma, metastasis
  • Imaging features can significantly overlapped and it can be difficult to tell one way of the other. Biopsy is usually required for definitive diagnosis.
Potential Clues:
  • Immunocompromised patients -- think of mycobacterial infection, lymphoma, Kaposi's sarcoma (esp. if there is cutaneous tumor), progressive generalized lymphadenopathy syndrome (lymphadenopathy in other locations)
  • Multiple lymph node stations, homogeneous nodes, hepatosplenomegaly -- think of lymphoma
  • Hyperenhancing -- think of hypervascular metastasis or Castleman disease
Our case: Retroperitoneal lymphadenopathy due to squamous cell carcinoma metastasis from head and neck cancer.

1. Warshauer DM, Lee JKT, Patel H. Retroperitoneum. In: Lee JKT et al (eds), computed body tomography with MRI correlation, 4th edition, 2006.
2. Chapman S, Nakielny R. Aids to radiological differential diagnosis, 4th ed, 2003.

October 3, 2009

Posterior Reversible Encephalopathy Syndrome (PRES)

Fig. 1: Axial non-contrast CT image in a 57-year-old hypertensive man shows ill-defined areas of low attenuation in the posterior occipital lobe (arrows).
Fig. 2: Axial FLAIR MR image confirms the abnormality in cortical and subcortical white matter of the posterior aspect of the occipital lobes (arrows), relative sparing of the paramedian occipital regions. There is no contrast enhancement or restricted diffusion.

Facts: Posterior Reversible Encephalopathy Syndrome (PRES)
  • Usually reversible neurologic syndrome presenting with reversible headache, altered consciousness or vision loss accompanied by reversible imaging abnormalities
  • Related to hypertension, eclampsia and preeclampsia and immunosuppressive medication (and several other causes have been described)
  • Believed to be due to hyperperfusion state with blood brain barrier breakthrough
Typical Imaging Appearances
  • CT is often abnormal at the time of presentation. MRI shows more lesions and extent.
  • Cortical or subcortical edema
  • Preferential involvement of posterior aspect of the lobes, particularly parieto-occipital lobes (gradient effect present)
  • Sparing of calcarine and paramedian occipital lobe structures
  • Usually bilateral
Our case: PRES (typical imaging appearance)

1. Hinghey J, Chaves C, Appignani B, et al. A reversible posterior leukoencephalopathy syndrome. New Eng J Med 1996;334:494-500.
2. McKinney AM, Short J, Truwit CL, et al. Posterior reversible encephalopathy syndrome: incidence of atypical regions of involvement and imaging findings. AJR 2007;189:904-912.