September 30, 2010

Perinephric Stranding with Dilated Ureter

Axial CT images show mild enlargement of the right kidney, perinephric fat stranding and dilated right renal pelvis, right ureter to the right ureterovesical junction (UVJ).

Differential Diagnosis
  • UVJ obstruction (tumor, stricture, nonopaque calculus)
  • Recently passed ureteric calculus
  • Renal trauma
  • Acute pyelonephritis (usually no dilatation of collecting system)
  • Renal vein thrombosis (usually no dilatation of collecting system)
Our case -- passed ureteric stone, seen at the base of the urinary bladder. Make sure to scan the entire length of the urethra, or ask the patient if there has been any sudden relief of symptoms.

September 27, 2010

Radiologists Need to See Patients

The followings are summarized from the article "The Constantly Changing Field of Radiology: Maintaining Professionalism in an Era of Electronic Communication" by Alexander R. Margulis, MD.

PACS: Disruptive Innovation
  • Good: streamlining imaging process, allowing almost instant availability of images and of reports, eliminating film loss, speeding up patient care
  • Bad: reducing personal contact between radiologists and referring physicians, and radiologists and patients, making possible image interpretation from remote sites without any personal contact with treating physicians and little or no clinical information
The Problem
  • "These developments threaten to change radiology into a commodity and radiologists, in patients' eyes, into nonparticipants in their care."
  • Radiologists are not known by (or exist to) patients
  • The notion endangers the role of radiologist as a physician, and the existence of radiology specialty
  • See patients. "Radiologists need to see patients before imaging examinations to make it clear that they are supervising and will later interpret the examinations."
  • "If possible and appropriate, they should even give patients preliminary readings."
  • This can start in teaching centers, where faculty, fellows and/or residents take turns as "officer of the day" greet patients, determine examination protocols, and participate when the cases are reviewed
At the end of the article, Dr. Margulis predicts that "the radiologists of tomorrow will return to playing their full role as physicians. They will not only sit in front of PACS monitors interpreting images, but will see patients and remain continuously in touch with their clinical colleagues."

Margulis AR. The constantly changing field of radiology: maintaining professionalism in an era of electronic communication. Radiology 2010; 257:22-23.

September 24, 2010


Axial CT image of the neck shows an enlarged left parotid gland (star) with blurry margins, nearby fat stranding. There is no internal low attenuation areas.

  • Infection of the parotid gland caused by bacterial, viral pathogen or is calculus-induced.
  • Acute suppurative parotitis is usually unilateral
  • Bacterial parotitis is usually caused by S aureus (greater than 50% of cases) and anaerobic bacteria
  • May be complicated by abscess formation, thrombophlebitis, cranial nerve VII dysfunction
  • Treatment: hydration, antibiotics, possible drainage if an abscess develops
CT Findings:
  • Diffuse enlargement and enhancement of the parotid gland
  • Blurred margins of the gland
  • Internal low attenuation indicative of abscess formation
Capps EF, Kinsella JJ, Gupta M, et al. Emergency imaging assessment of acute, nontraumatic conditions of the head and neck. Radiographics 2010; 30:1335-1352.

September 21, 2010

Lung Cancer: Chest Wall and Pleural Invasion

Axial CT image shows a large left upper lobe mass (star) with adjacent rib destruction (arrow) in a patient with T3 lung cancer.

  • Contiguity of the neoplasm with pleural surface is not equivalent to invasion
  • Major CT finding of pleural and chest wall invasion is bone destruction or a chest wall mass
  • Other CT criteria: extent of contact of the mass and its angle with the pleura, presence of fat plane between the tumor and chest wall
  • Chest wall and pleural invasion is considered T3 disease

UyBico SJ, Wu CC, Suh RD, et al. Lung cancer staging essentials: the new TNM staging system and potential imaging pitfalls. Radiographics 2010; 30:1163-1183.

September 18, 2010

Partial Anomalous Pulmonary Venous Return (PAPVR)

Figures 1-3: Contiguous axial contrast-enhanced CT images show an abnormal left upper lobe pulmonary vein draining into the left vertical vein (arrows) that subsequently empties into the left brachiocephalic vein (BCV).

Facts: PAPVR
  • Common venous anomalies of the thorax (0.5% prevalence in general population)
  • Pulmonary-to-systemic, left-to-right shunt
  • Anomalous pulmonary vein drains into the right sided circulation (SVC, azygos, brachiocephalic, IVC, coronary sinus, right atrium)
  • Symptomatic if large or associated with other cardiopulmonary anomalies
  • Most common form = right upper lobe vein draining into SVC, left upper lobe vein draining into left vertical vein
  • Surgical correction recommended if pulmonary-to-systemic flow ratio greater than 1.5 to avoid progression to pulmonary hypertension and right ventricular failure
Martinez-Jimenez S, Heyneman LE, McAdams HP, et al. Nonsurgical extracardiac vascular shunts in the thorax: clinical and imaging characteristics. Radiographics 2010; 30,e41-.

September 15, 2010

Post-Endovascular Rx of Thoracic Aortic Injury

An axial CT image shows a normal appearance of an endovascular stent in the descending thoracic aorta in a patient who suffered thoracic aortic injury.

Facts: Treatment and Follow Up of Thoracic Aortic Injury (TAI)
  • Open thoracotomy with direct repair of TAI is a traditional means for Rx of TAI. However, endovascular Rx has become more common given its less invasiveness and many reports demonstrating smaller mortality rate
  • Endovascular Rx is used to exclude pseudoaneurysm from systemic arterial pressure
  • Patients who had endovascular Rx for TAI will require regular imaging follow-ups. Most institutions perform CT angiography at the time of discharge, at 1-3 months, at 6 months, at 1 year and then annually.
  • Purpose of follow up CT angiography after endovascular Rx is to 1) assess quality of pseudoaneurysm exclusion, 2) detect related complications
  • Complications potentially detectable on imaging (rare): endoleak, graft collapse, branch vessel complications (stroke, arm ischemia), stent migration, etc
Normal Imaging Findings
  • Endograft = metallic framework with a zigzag appearance (covered by polytetrafluorethylene or polyester material)
  • Must compare the CT angiography with prior angiography (post-stent) or prior post-operative CT
  • Check for position of endograft (should be unchanged), apposition/seal with the aortic wall (should be completely sealed), patent endograft lumen (without narrowing or sharp angulation), total exclusion of aortic injury


Morgan TA, Steenburg SD, Siegel EL, Mirvis SE. Acute traumatic aortic injuries: posttherapy multidetector CT findings. Radiographics 2010; 30:851-867

September 12, 2010

Painful Bipartite Patella

Coronal T1W MR image of the right knee in a patient with anterior knee pain shows a bipartite patella. Note cartilage lining of the synchondrosis (red arrowheads).

Axial fat-suppressed T2W image shows bone marrow edema within the bipartite segment (arrow) with small joint fluid (yellow arrowhead).

Facts: Bipartite Patella
  • Developmental variation of an unfused accessory ossification center
  • Typical location at superolateral aspect of the patella, at insertion of vastus lateralis
  • This ossification center begins to ossify at age 3-5, and fuse by age 12; if unfused - it is called bipartite patella
  • Almost always bilateral, male much more common than female
  • Prevalence about 2% of population
  • Most discovered incidentally
Painful Bipartite Patella
  • Unrecognized cause of anterior knee pain
  • It is postulated that synchondrosis of bipartite patella becomes disrupted due to overuse or acute injury, allowing abnormal motion, friction and subsequent edema
  • "Rather than discounting it as a normal variant, a detailed search should be undertaken for signs of edema both within the bipartite fragment and along the margins of the synchondrosis or pseudarthrosis, especially in patients presenting with anterior knee pain." -- quoted from Kavanagh EC, et al (paper referenced below)
  • In one study of 53 patients with bipartite patella, almost half of them had findings consistent with marrow edema in the bipartite segment (which probably responsible for pain)
Kavanagh EC, et al. MRI findings in bipartite patella. Skeletal Radiol 2007;36:209-214.

September 9, 2010

Krukenberg Metastasis

Fig. 1: Axial CT image shows circumferential thickening of the gastric antrum.
Fig. 2: Axial CT image of the pelvis shows bilateral, predominantly solid, less than 10 cm, ovarian masses (stars). There is small ascites.

Facts: Krukenberg Metastasis
  • Originally described by Dr. Krukenberg in reference to a rare form of malignant ovarian signet-ring tumor that distinction between primary and metastatic signet-ring tumors from the stomach was difficult
  • Differentiation between Krukenberg metastatic signet-ring ovarian tumors vs. primary has implication for management and prognosis. Primary signet-ring ovarian tumors can be treated with resection if found early. Krukenberg tumors are indicative of late-stage disease
  • Primarily from gastrointestinal adenocarcinoma (stomach, colon)
Imaging Findings
  • Distinction between primary and metastatic ovarian tumors can be difficult on imaging. There is no reliable, consistent feature that is accurate enough to differentiate the two
  • Radiologist may suggest possible Krukenberg metastasis if ovarian lesions are solid, less than 10 cm, involve both ovaries and present late.
Our case: Signet-ring adenocarcinoma of the stomach with bilateral ovarian metastases (Krukenberg metastasis)

1. Brown DL, Zou KH, Tempany CMC, et al. Primary versus secondary ovarian malignancy: imaging findings of adnexal masses in the radiology diagnostic oncology group study. Radiology 2001;219:213-218.
2. Zagoria RJ, Mayo-Smith WW, Fielding JR. Genitourinary imaging case review series, 2nd edition, 2008.

September 6, 2010

Mesoblastic Nephroma

A 10-day-old infant presented with hematuria. Multiple CT images show a large heterogeneous mass originating from the lower pole of the right kidney (cortical beak sign noted, pink arrow). The mass extends into the right renal pelvis and causes mild hydronephrosis.

  • Synonyms: mesoblastic nephroma, leiomyomatous hamartoma, mesenchymal hamartoma, renal fibroma, Bolande tumor.
  • It is the most common solid renal tumor in the newborn.
  • This tumor is believed to arise from metanephric blastema or secondary mesenchyme.
  • Patients usually presents with a palpable flank mass.
  • Prognosis is excellent with nephrectomy and wide resection
Imaging Findings
  • Large solid intrarenal mass, which typically involves or extends to the renal sinus.
  • Hemorrhage, necrosis or cystic portions are uncommon.
Table: Age Presentation of Renal Tumors in Children


1. Donnelly LF. Diagnostic imaging pediatrics. Amirsys. Manitoba. 2005.
2. Lowe LH, Isuani BH, Heller RM, Stein SM, Johnson JE, Navarro OM, Hernanz-Schulman M. Pediatric renal masses: Wilms tumor and beyond. Pediatric renal masses: Wilms tumor and beyond. Radiographics. 2000; 20:1585-603.

September 3, 2010


Axial CT image shows subpleural reticulation at the periphery of the lung bases bilaterally. Also note thin linear subpleural lines paralleling the pleural surface (arrowheads). There are several calcified pleural plaques in the diaphragmatic pleura (star).

  • Only asbestos fibers of 20-150 um in length can reach lower respiratory tract and cause diseases
  • Asbestos bodies are formed by macrophages phagocytose the fibers
  • Pulmonary fibrosis develops initially in peribronchiolar region and then spreads along peribronchovascular and septal connective tissues, predominantly in the lower lung zones. Cicatricial emphysema and traction bronchiectasis finally ensues.
  • Patients usually present late after initial exposure (up to 20 years)
Imaging Findings
  • Difficult to discern on radiograph because pleural involvement often is more conspicuous and may obscure early lung findings
  • Dot-like opacities in subpleural lung may be an earliest CT finding of asbestosis
  • Curvilinear subpleural lines (as in our case) are lines running parallel to and a few millimeters beneath the pleural surfaces
  • Thickening of interlobular septa and intralobular lines
  • Traction bronchiectasis and honeycomb lungs (late)

Lange S, Walsh G. Radiology of chest diseases, 3rd ed, 2007.