Fatty Liver

Axial "in-phase" MR image shows increased signal intensity of the liver.

Axial "opposed-phase" MR image shows decreased signal of the entire liver when compared with the same areas on in-phase image. 

Facts

• Triglyceride accumulation within cytoplasm of hepatocytes
• Can be due to alcoholic liver disease, nonalcoholic fatty liver disease, viral hepatitis, drugs
• May progress to steatohepatitis and cirrhosis
• Avoid the use of "fatty infiltration of the liver", which is misleading because fat deposition in Fatty Liver is in hepatocytes - rarely in other cell types
• Sensitivity/specificity for detection:
• Ultrasound = 60-100% / 77-95%
• Non-contrast CT = 43-95% / 90%
• Chemical-shift MRI = 81% / 100%

MR Imaging

• Because protons in water and fatty acid molecules precess in different resonance frequency, proton chemical shift imaging can be utilized to image this difference
• If images are obtained when fat and water protons are "in-phase", their signals are additive (brighter). If they are "out-of-phase", their signals cancel each other (structure becoming darker)
• Amount of hepatic fat can be quantified by assessing the degree of signal loss

Reference

Hamer OW, Aguirre DA, Casola G, et al. Fatty liver: imaging patterns and pitfalls. Radiographics 2006; 26:1637-1653.

Enhanced Intervertebral Disc in Post-discectomy Patients

Sagittal, fat-suppressed T1W MR images of the spine without (above) and with (below) IV contrast show two band enhancement of L4/5 disc (arrows), which parallel to the endplates of an asymptomatic post remote-discectomy patient. 

 Facts: Imaging of Postoperative Lumbar Discectomy

• Intervertebral disc enhancement, annular enhancement and vertebral body enhancement are generally suggestive signs of disc space infection in post-discectomy patients
• However, some patients without clinical signs/symptoms of infection may have abnormal enhancement of disc/endplate and annulus. 
• In a study of 94 patients without clinical infection, post-operative MRI (3-6 months after surgery) shows anular enhancement in almost all cases and 20% of patients have disc enhancement that are not present on preoperative MRI
• Suggestive pattern of "incidental" enhancement: linear enhancement within the disc (two thin bands paralleling the end plates). Authors postulate that this could be due to accelerated degenerative disc change, unrelated to infection

Reference:

Ross JS, Zepp R, Modic MT. The postoperative lumbar spine: enhanced MR evaluation of the intervertebral disk. AJNR Am J Neuroradiol 1996;17:323-331.

Tuberous Sclerosis Complex

Axial T1W MR image of a 5-year-old girl demonstrates several T1-hyperintense subependymal nodules arrows).

Coronal FLAIR MR image shows multiple cortical tubers and subcortical white matter hyperintensities (asterisks).

Facts

• Autosomal dominant disorder due to abnormality of TSC1 and TSC2 genes
• Most frequent clinical manifestations are neurologic (myoclonic seizures in early childhood, psychiatric symptoms, retinal hamartomas) and skin (adenomas of sebaceous glands)

Diagnostic Criteria by Tuberous Sclerosis Complex Consensus Conference (Maryland 1998)

Major features

• Facial angiofibromas or forehead plaque
• Nontraumatic ungual or periungual fibroma
• Hypomelanotic macules (more than 3)
• Shagreen patch (connective tissue nevus)
• Cortical tuber
• Subependymal nodule
• Subependymal giant cell astrocytoma
• Multiple retinal nodular hamartomas
• Cardiac rhabdomyoma, single or multiple
• Lymphangiomyomatosis (LAM)
• Renal angiomyolipoma (AML)

Minor features

• Multiple randomly distributed pits in dental enamel
• Hamartomatous rectal polyps
• Bone cysts
• Cerebral white matter "migration tracts"
• Gingival fibromas
• Nonrenal hamartoma
• Retinal achromic patch
• Confetti skin lesions
• Multiple renal cysts

Definite TSC: Either 2 major, or 1 major + 2 minor features

Probable TSC: One major + one minor feature

Possible TSC: Either 1 major, or 2 or more minor features

----

Imaging findings are highlighted in red.

When both LAM and renal AML are present, other features should be present as well before definite diagnosis is made. 

Reference:

Roach ES, Sparagana SP. Diagnosis of tuberous sclerosis complex. J Child Neurol 2004;19:643-649. Fulltext

Sellar Mass with Calcification

Sagittal images (upper left = CT, upper right = T2W MR, lower left = T1W MR, lower right = T1W post-contrast MR) of the pituitary region of an elderly individual show a large sellar/suprasellar mass with internal calcification (hyperdense on CT, signal loss on MR). The mass is mostly solid and reveals heterogeneous enhancement. Note ballooning of the sella.

Differential diagnosis of a calcified sellar mass:

• Craniopharyngioma (most likely)
• Pituitary adenoma (unlikely, 0.2% - 8% have calcification)
• Rathke's cleft cyst (rare disease)
• Chordoma (rare disease)

Associated findings that help DDx:

• Nodular appearance of calcification --> craniopharyngioma
• Calcifications in a cystic mass --> craniopharyngioma
• Curvilinear appearance of calcification --> pituitary adenoma or Rathke's cleft cyst
• Bone destruction --> chordoma

This is a rare case of sellar/suprasellar chondrosarcoma confirmed with histology. 

Reference:

Kasliwal MK, Sharma BS. A rare case of pituitary adenoma with calcification: a case report. Turkish Neurosurg 2008;18:232-235

Glezer A, et al. Rare sellar lesions. Endocrinol Metab Clin N Am 2008;37:195-211. 

Uterine Leiomyoma on MRI

Leiomyoma in a 28-year-old woman. Sagittal MR images in T2W (A), T1W (B) and post-contrast T1W (C) show a large, rounded, circumscribed mass in the anterior wall of the uterus (U) that pushes the bladder (B) anteriorly. The mass demonstrates T2 hypointensity, T1 isointensity and heterogeneous enhancement. 

Facts

• Most common uterine neoplasms with prevalence up to 40% of women of reproductive age
• Benign tumors of smooth muscle with variable amount of fibrous tissue
• Surrounded by pseudocapsule and supplied by one or two large vessels
• Greater than 90% from uterine body
• Classified on their position relative to uterine wall (submucosal, intramural or subserosal)

MR Imaging Findings

• Well-circumscribed mass
• Classic signal intensity: T1 isointensity, T2 hypointensity, variable enhancement
• If T1 hyperintense, think hemorrhage
• If T2 hyperintense, think cellular leiomyoma
• If no enhancement, think partially or completely infarcted leiomyoma

References

Hricak H. MRI of the pelvis: a text atlas

Hamm B, et al. MRI and CT of the female pelvis. 

Olfactory Groove Meningioma

Axial T2W MR image shows a lobulated extraaxial mass in the midline anterior cranial fossa. The mass is T2 isointense with a central area of higher T2 signal intensity. Mild brain edema of the inferior frontal lobes are noted. 

Sagittal post-contrast T1W MR image shows uniform enhancement of the mass.  It better demonstrates the location of the mass that is anterior to the tuberculum sellae.

Facts: Olfactory Groove Meningioma

• Usually asymptomatic until large. 
• When symptomatic, they can produce Foster Kennedy syndrome (anosmia, ipsilateral optic atrophy, contralateral papilledema), metal status change, urinary incontinence
• Histological variables follow WHO grading I to III (from low recurrence to high rates of recurrence with aggressive growth)
• Atypical meningioma, rhabdoid and malignant meningioma have greater risk of recurrence
• Brain invasion increases likelihood of recurrence but not indicator of malignant grade
• "Olfactory groove" is anterior to tuberculum sellae (distinction between tuberculum vs olfactory groove meningioma). Tuberculum sellae is bony elevation between chiasmatic sulcus and sella turcica. See tuberculum sellae meningioma here (external site)

MRI Findings

• T1 and T2 isointensity
• Most enhances with gadolinium
• Dural tail
• Signal voids in the lesion due to calcifications

Reference:

Cranial Base Center of Massachusetts General Hospital website 

Lipoma of Filum Terminale

Sagittal T1W image shows a T1 hyperintense mass at the filum terminale and a thin fatty strand extending from the tip of the conus medullaris to the coccyx.

Sagittal T2W image with fat suppression demonstrates signal loss of the mass, indicating presence of fat.

Facts:

• Abnormal retrogressive differentiation of pleuripotential cells found in distal caudal mass
• Mostly incidental, found in 5% of lumbar spine MRI but may be associated with tight filum terminale syndrome
• Fat is clearly separable from nerve roots and conus medullaris that terminates at above L2 level

Imaging

• Fat intensity mass (hyperintense T1, hyperintense T2, and progressive lower signal on greater T2 weighting)
• Can be intradural or extradural
• Intradural fatty filum is fusiform, tapering down toward where the filum pierces the dura
• Extradural fatty filum is often larger, more diffuse, elevating/distorting distal thecal sac

Reference:

Atlas SW. Magnetic resonance imaging of the brain and spine, 4th edition, 2009

Hemochromatosis

A&C: MRI out-of-phase imaging. B&D: MRI in-phase imaging
Signal decrease of the liver on B&D (in-phase images) when compared with A&C (out-of-phase images). Note innumerable Gandy-Gamna bodies in the spleen. 

Facts

• Hemochromatosis = iron overload
• Primary vs. secondary hemochromatosis
• Primary: autosomal recessive genetic disorder involving increased iron absorption. This is the most common genetic disease in white population
• Secondary: nongenetic causes of iron accumulation in organs such as cirrhosis, myelodysplastic syndrome, thalassemia
• Diagnosis is made with serum ferritin level and transferrin saturation index (but low sensitivity and specificity), genetic test and biopsy. Biopsy is reference standard
• Imaging such as non-contrast CT and MRI can be used to diagnose hemochromatosis but MRI is the best method

MRI Findings

• Iron accumulation in tissues cause local distortion of magnetic fields and spin relaxation, resulting in shortening T1, T2 and esp. T2* 
• Loss of signal intensity in affected organs proportional to iron deposition
• Dual-sequence (gradient in and out of phase) is typically used 
• Decreased signal intensity on in-phase images compared with out-of-phase images "opposite of hepatic steatosis"
• General MR protocols are not adequate to estimate hepatic iron concentration. Special sequences (i.e., GRE T2* with progressively longer echo times) are needed for this purpose
• Iron excess deposition may suggest etiology
• Reticuloendothelial system (i.e., liver and spleen): secondary hemochromatosis
• Parenchymal depositition pattern (i.e., liver only, possible pancreas): primary hemochromatosis or chronic anemia with insufficient erythropoiesis
• Mixed deposition pattern (atypical distribution): anemia+multiple blood transfusions

This patient has hemochromatosis secondary to cirrhosis. 

Reference:

Queiroz-Andrade M et al. MR imaging findings of iron overload. RadioGraphics 2009;29:1575-1589. 

Arachnoid Cyst

Axial T1W MR image shows a large T1 hypointense extra axial lesion in the left parietal region (arrow). 

Coronal T2GRE and T2W images demonstrate homogeneous T2 hyperintensity of the mass that follows CSF signal. There is compression of the adjacent gyri.  

Facts: Arachnoid Cyst

• Congenital lesion arising during development from splitting of arachnoid membrane
• Contains fluid usually identical to CSF
• Do not communicate with ventricles or subarachnoid space
• Lined with meningothelial cells 
• Incidence: 5 in 1,000 autopsies. 1% of intracranial masses
• Predominant male
• Mostly asymptomatic

Imaging:

• Extraaxial cystic mass with pressure effect to underlying brain
• Signal intensity follows CSF in all sequences
• No restricted diffusion
• Most common location (from highest to lowest frequency: Sylvian fissure (almost 50%), cerebellopontine angle, supracollicular, vermin, sella/suprasella

Reference:

Greenberg MS. Handbook of Neurosurgery, 7th edition. 2010

Pancreatic Divisum

An MRCP image shows abnormal drainage of the main pancreatic duct and ventral duct into the minor papilla.

A diagram shows normal pattern of pancreatic duct drainage (label "normal") and pancreatic divisum. Several variants of pancreatic divisum exist but the "classic/typical" one is the MPD draining into the minor papilla while the VD draining into the major papilla along with the CBD. Santorinicele is a fusiform dilatation of the distal MPD before it enters the minor papilla. 

Facts: Pancreatic Divisum 

• Most common pancreatic anatomic variant, found 7% incidence at autopsy but frequencies differ at ERCP
• Controversial association with recurrent pancreatitis
• Results of non-fusion of ventral and dorsal pancreatic anlagen during embryonic time, therefore the ducts (ventral and dorsal ducts are not fused)
• Dorsal duct drains most of glandular parenchyma through minor papilla
• Ventral duct drains a portion of pancreatic head (including uncinate process) through major papilla

Imaging:

• Definitive diagnosis is made with ERCP. MRCP does have high sensitivity and specificity for diagnosis of divisum
• MDCT with thin section can be used to diagnose pancreatic divisum. Viewing images on PACS is essential for depiction of this condition and the assessment is possible only when the pancreatic duct is visualized.
• Important criterion = Dorsal duct seen from tail and body through the anterior aspect of the head, draining into minor papilla (located anterior to CBD and major papilla) while the ventral duct seen in posterior region of the pancreatic head and drains into duodenum together with CBD. Dorsal duct is larger than ventral duct and they are not communicated with each other. "Dominant dorsal duct sign"

Reference:

Soto JA, Lucey BC, Stuhlfaut JW. Pancreas divisum: depiction with multi-detector row CT. Radiology 2005; 235:503-508. 

Sternal Osteomyelitis

Chest radiograph of a patient who had sternal pain, fever and discharge shows no obvious bony abnormality.

Sagittal STIR and coronal T1W MR images demonstrate bone marrow edema with soft tissue changes in the sternum and right sternoclavicular joint (arrows). 

Facts:

• Uncommon infection of the sternum and sternoclavicular joint
• Usually affecting drug addicts, individuals with history of recent subclavian catheter placement, and patients with chronic debilitating illnesses
• Inciting organisms vary widely depending on demographics
• High failure rates of medical treatment alone. Typical treatment includes surgical debridement and en bloc removal

Imaging

• Radiograph is rarely helpful
• CT may show bone destruction but this may be late because damage begins in the joint. Surrounding soft tissue abnormalities are often a useful sign.
• MRI much more sensitive to detect joint and bone changes that are similar in findings to other areas of bone/joint infection

Reference: 

Shields TW et al. General Thoracic Surgery, 7th edition, 2009.

Limbus Vertebra

LS spine x-ray, sagittal-reformatted CT and sagittal T1W MR images demonstrate a limbus vertebra in the anterosuperior corner of L4 vertebral body in this 32-year-old woman.

Facts

• Intrabody herniation of disc material at the margin of the endplate, occurs during spinal growth before skeletal maturity
• Herniation of nuclear material through the cartilaginous junction zone of ring apophysis may isolate this ossification center from the body margin, inhibiting osseous fusion to the vertebral body
• Up to 5% of cadavers
• Generally asymptomatic

Imaging

• Smoothly corticated triangular fragment of bone at the corner of the vertebral body
• Most common in midlumbar spine (L2-4) but can be at any level including cervical spine
• Most common at the anterosuperior corner of the vertebral body
• Typically displaced farther from margin of vertebral body

References:

Ghelman B, Freiberger RH. The limbus vertebra: an anterior disc hernation demonstrated by discography. AJR 1976; 127:854-855

Atypical Hepatic Hemangioma - Rapid Filling of Contrast

Axial MR images in multiple phases (as labeled) show a T1 hypointense nodule in the right hepatic lobe that rapidly filled in with contrast after administration and subsequently fades on delayed imaging. Note that the enhancement of the nodule is similar to the aorta in all phases. On T2W image (not shown), this nodule has a very high signal intensity. 

Rapidly Filling Hemangioma

• 16% of all hepatic hemangiomas
• More common among small (<1 1="1" 42="42" cm="cm" hemangioma="hemangioma" hemangiomas="hemangiomas" in="in" incidence="incidence" less="less" li="li" of="of" than="than">
• Immediate homogeneous enhancement at arterial phase and hyperintensity persists in delayed phases. Enhancement equal to aorta in all phases. 
• High T2 signal intensity may be helpful for differentiation from other arterial enhancing nodules (but it can also be seen in islet cell tumor metastasis)

Reference:

Vilgrain V et al. Imaging of atypical hemangiomas of the liver with pathologic correlation. Radiographics 2000; 20:379

Pelvic Ewing's Sarcoma

A pelvic radiograph of a 5-year-old girl shows a large lytic lesion in the left iliac bone (arrows).

An axial FDG PET/CT image shows high metabolic activity of the mass involving the left iliac bone with soft tissue component and bone destruction. A coronal T2W MR image reveals an extensive soft tissue mass with necrotic areas and involvement of the adjacent musculature. 

Differential Diagnosis

• Metastatic neuroblastoma. Given her age at five years old, this needs to be in differentials
• Ewing's sarcoma
• Telangiectatic osteosarcoma
• Osteomyelitis. Great mimics of aggressive-looking bone tumor. Symptoms may overlap with round-cell tumor, including fever

This case: Ewing's sarcoma by tissue diagnosis (+ve PAS and vimentin).

Facts: Ewing's Sarcoma

• Malignant round-cell tumors of the bone with neural cell origin
• Tumors of children and young adults, most between 10-20 years old. Less than 2% occur in children less than 5 years old
• Most common sites = femur >> pelvis
• Pelvic Ewing's -- bad prognosis because there is no anatomic barrier to tumor spread, close proximity to viscera and neurovascular bundles, prone to recur

Reference:

Bhagat S, Sharma H, Pillai DS, Jane MJ. Pelvic Ewing's sarcoma: a review from Swedish Bone Tumour Registry. J Orthop Surg 2008;16:333-8

Spinal Langerhans Cell Histiocytosis (LCH)

Figure 1: Tc-99m MDP bone scan (posterior image) shows a focus of increased activity at L2 vertebral body in a 24-year-old woman presenting with back pain.

Figures 2&3: Axial GRE T2W and sagittal post-contrast T1W MR images show a round focus of bone destruction surrounded by bone marrow edema and enhancement of L2 body, sparing the posterior elements. 

Facts: LCH

• Rare, benign disorder of unknown etiology comprises of eosinophilic granuloma (unifocal), Hand-Schuller-Christian disease (multifocal) and Letterer-Siwe disease (disseminated variant) - these are different manifestations of a same disease
• Clonal proliferation of Langerhans cells
• Peak incidence 5-10 years but there is a shift toward younger children

Spinal LCH

• Vertebral involvement in 8-25% of cases
• Thoracic > cervical, lumbar
• Vertebral body >> posterior elements
• Solitary, well-defined osteolytic lesion with scalloped borders eventually progresses to collapse and a classic "vertebra plana"
• Typically single vertebral body involved. Disc spaces spared
• Soft tissue mass suggests more aggressive course

Main Imaging Differentials of Spinal LCH

• Osteomyelitis
• Ewing sarcoma
• Leukemia, lymphoma, metastatic neuroblastoma

Reference:
Hosalkar HS, Greenberg JS, Wells L, Dormans JP. Isolated Langerhans Cell Histiocytosis of the T12 vertebra in an adolescent. Am J Orthop 2007;36: E21-E24.

Focal Fat Sparing

Figure 1: US image of the liver shows focal masslike area of hypoechogenicity of the left lobe posterior to the left portal vein branch. Note high echogenicity of the background liver, suggesting fatty change.

Figure 2 & 3: In-phase and out-of-phase MR images show liver signal intensity drop in the chemical shift imaging confirming diffuse fatty liver. The abnormality in the left lobe liver does not change between the two phases, suggesting a focal area of fat sparing.

Facts: Fatty Liver

• Most common abnormality of the liver seen on cross-sectional imaging
• Common patterns: diffuse fat accumulation, diffuse fat accumulation with focal sparing, and focal fat accumulation in an otherwise normal liver
• Unusual patterns may mimick neoplasm, inflammation or vascular conditions
• Pathology: triglyceride acculation within cytoplasm of hepatocytes
• Term "fatty liver" is preferred over "fatty infiltration of the liver" because triglyceride accumulation occurs within hepatocytes but rarely other cell types. Infiltration of fat into parenchymal does not occur

Imaging Findings and Sensitivity/Specificity

• US: 1) Liver echo greater than renal cortex and spleen with attenuation of sound wave, 2) loss of definition of diaphragm, 3) poor delineation of intrahepatic architecture (to avoid false-positive diagnosis, all three findings should be fulfilled).  Sensitivity 60-100%. Specificity 77-95%.
• CT: Liver attenuation 10 HU less than that of spleen, or less than 40 HU. Sensitivity 43-95%. Specificity 90%.
• MRI: Signal intensity loss on opposed-phase images in comparison with in-phase images. Sensitivity 81%. Specificity 100%.

Patterns

1. Diffuse deposition: most common
2. Focal deposition and focal sparing: characteristically in specific areas (adjacent to falciform ligament or ligamentum venosum, porta hepatis, in GB fossa). Suggestive findings of fatty pseudolesions rather than true masses are:
1. Fat content
2. Characteristic location
3. Absence of mass effect on vessels and other liver structures
4. Geographic configuration (not round or oval)
5. Poorly delineated margin
6. Contrast enhancement similar to or less than that or normal liver parenchyma
3. Multifocal deposition
4. Perivascular deposition
5. Subcapsular deposition

Reference:


Hamer OW, Aguirre DA, Casola G, et al. Fatty liver: imaging patterns and pitfalls. Radiographics 2006;26: 1637-1653.

Age-related White Matter Changes

MR FLAIR images show multiple FLAIR hyperintense foci in bilateral periventricular and deep white matter in a 77-year-old patient.

Facts:

• Several possible mechanisms but at present it is believed to be an incomplete ischemia mainly related to cerebral small vessel arteriolosclerosis
• Pathology: partial loss of myelin, axons, oligodendroglial cells; mild reactive gliosis, astrocytic gliosis, stenosis of arterioles from hyaline fibrosis
• Important substrates for cognitive impairment and functional loss in the elderly
• Very common in elderly with hypertension, diabetes, hyperlipidemai

Imaging

• Ill-defined hypodensities on CT
• T1 hypointensities, T2/PD/FLAIR hyperintensities. FLAIR best to demonstrate severity of disease
• When the largest lesion is adjacent to ventricles, it's called periventricular white matter changes
• On diffusion tensor MRI, there is elevation of diffusivity and reduced fractional anisotrophy (FA) meaning impaired white matter integrity

Reference:
Xiong YY, Mok V. Age-related white matter changes. J Aging Res 2011

Calcaneal Hemangioendothelioma

Authors: Bahri Nandini, M.D. and Sanjay B. Nathani, M.D. (Radiodiagnosis)

Editor: Rathachai Kaewlai, M.D.

Ankle radiograph shows a well defined lytic lesion with few septa in the anterior part of the calcaneus. There is cortical destruction at the medial and superior cortex of the calcaneus.

Sagittal PDT2W and coronal T1W MR images of the hindfoot show a lobulated mass with internal septa in the anterior part of the calcaneus with etension into the adjacent myofascial planes. The lesion is hypointense on T1W and hyperintense on T2W sequences.

Quick Facts:

• Hemangioendothelioma and angiosarcoma are a group of primary malignant vascular tumors of the bone, which are extremely rare
• Common locations: femur, tibia, pelvis and vertebra
• Age group: between 4th and 5th decade
• Imaging appearance: lytic lesion without sclerotic border, multilocular, bone expansion and laminated periosteal reaction
• Common differential diagnosis = aneurysmal bone cyst, simple bone cyst
  

The Case

• A 50 years old female presented with pain and swelling at left foot with no history of trauma. On clinical examination local tenderness at heal was present.
• Radiograph taken in oblique (fig 1) positions, showed a well defined, lobulated lytic lesion with a few internal septa in the anterior part of Calcaneum. The lesion extends and breaches the medial and superior cortex of calcaneum
• MRI study of foot and ankle using 1.5T Siemens Magnetom Essenza machine, which included T1, T2, PD and T2 fat suppressed axial, sagittal and coronal sequences were performed. On PDW sagittal and T1 coronal images the lesion appears well defined, lobulated , with few internal septas in the anteroinferior part of calcaneum and breaches the medial and superior cortex and involves the adjacent myofascial planes. The lesion is hyperintense on PDW images [figure 2 A] and hypointense in T1W coronal images [figure 2 B] Tibiotalar joint shows minimal joint effusion.
• On histopathological examination of the material obtained after intraoperative curettage of calcaneum findings were in favor of tumor of vascular origin.
• On the basis of the clinical, radiological and histopathological findings, presumptive diagnosis of Calcaneal Hemangioendothelioma was considered.

Discussion

• Hemangioendothelial sarcoma includes hemangioendothelioma and angiosarcoma, which encompasses a group of primary malignant vascular tumors in bone that vary from the malignant capillary and cavernous blood vessel formation to the proliferative endothelial sarcomas. Hemangioendothelioma is a tumor of blood vessels, in which endothelial cells are seen as predominant cell
• Primary malignant vascular tumors in bone are extremely rare(less than 1% of all bone tumors). It can occur in all age groups; however most of the patients are between 4^th and 5^th decades of life. Most commonly affected bone is Femur (16%), followed by Tibia(14%), pelvis(12%), vertebra(10%). Other rare sites are foot, hand, forearm bones and clavicle. The patient may not experience any specific symptoms or signs. Patient may present with Pain or occasionally swelling. Hemangioendothelioma shows multicentricity of lesions in the bones of the same extremity. On Radiographs, the solitary lesion is well circumscribed, lytic with no surrounding sclerosis or matrix mineralization, which shows internal septa which may be scant or incomplete. Occasionally it may show multilocular appearance. The tumor causes expansion, thinning and erosion of the cortex and often associated with a mild laminated periosteal reaction.
• On MR imaging, the lesion appears well defined, multilocular which is hyperintense on T2W and PDW images and hypointense on T1W images with internal septa. The lesion involves the surrounding soft tissue and involvement of multiple bones can occur.
• The etiology of unicameral bone cysts of the calcaneum is an enigma, just as it is with these lesions in other bones. Popular theories regarding the origin of bone cysts have been related to the long bones and the juxtaposition of the cyst to the growth plate
• Most commonly considered differential diagnoses are Simple Bone Cyst, Aneurysmal Bone Cyst. That can be differentiated by moth eaten erosion pattern and irregular margins of Hemangioendothelial sarcoma.

This case is a 50-year-old female with pathological findings of a tumor of vascular origin.

References:

1. Ackerman LV, Spujat HJ. Tumors of bones and cartilage. Atlas of tumor pathology. Armed Forces Institute of Pathology, Washington, DC, 1962

2. Jaffe HL, Lichtenstein L. Solitary unicameral bone cyst with emphasis on the roentgen picture. Arch Surg 1942;44:1004-1025

3. Smith RW, Smith CF. Solitary unicameral bone cyst of the calcaneum: a review of twenty cases. J Bone Joint Surg Am 1974;56:49-56.

About Authors: Drs. Nandini and Nathani work for the Department of Radiodiagnosis, G.G. Hospital, Jamnagar, Gujarat in India. Their work does not have any support for the work in the form of grants, equipments or drugs.

Hepatic Hemangioma: MR Findings

Axial MR images show a large left hepatic lobe mass that has a very high T2 signal intensity and peripheral nodular contrast enhancement and incomplete delayed fill-in.

Facts:

• Most common benign hepatic tumor
• Female:male ratio = 2:1 to 5:1
• Most are asymptomatic and found incidentally on imaging exams
• US, CT, MRI and nuclear medicine scan may demonstrate hemangioma
• Routine MR protocol for characterizing liver lesions = T1, FSE T2 (with fat suppression), dynamic gadolinium enhancement

MR Imaging Findings

• A mass with T1 hypointensity, strong T2 hyperintensity with a "light bulb" pattern on heavily T2W sequence
• Dynamic enhancement shows peripheral nodular enhancement (the nodules do not contact each other) with progressive centripetal enhancement. The inner ring of the enhancement is undulating.
• Washout phase: persistent homogeneous enhancement without heterogeneous or peripheral washout
• Small lesions may demonstrate homogeneous arterial enhancement but the enhancement will be persistent and homogeneous in washout phase.

Reference:

Lencioni R, Cioni D, Iartolozzi C. Focal liver lesions: detection, characterization, ablation. 2005

Anaplastic Astrocytoma

Axial T2W (fig. 1) and T1W post contrast (fig. 2) images of the brain demonstrate a large ill-defined mass (arrows) centered in the right insula with extension to the frontal and temporal lobes. The mass shows a heterogeneous high T2 signal intensity, cystic areas (arrowheads), mass effect and minimal enhancement.

Facts: WHO grading system for primary astrocytic tumor and imaging features

• Grade I = circumscribed glioma including pilocytic astrocytoma -- no mass effect, no enhancement
• Grade II = diffuse astrocytoma (cytological atypia alone) -- mass effect, no enhancement
• Grade III = anaplastic astrocytoma (anaplasia and mitotic activity) -- complex enhancement
• Grade IV = glioblastoma (also show microvascular proliferation) -- necrosis (ring enhancement)

Imaging

• Imaging grading is imprecise but can be used as a preliminary assessment
• Grading is not applicable to pediatric patients or special astrocytomas
• Low grade gliomas usually hypodense on CT, hypointense on T1WI and hyperintense on T2WI. High T2 signal intensity commonly extends beyond the tumor volume. Most do not enhance.
• Anaplastic gliomas may or may not enhance. Calcifications and cysts occur in 10-20%.
• Glioblastomas usually enhance on the rim, representing cellular tumor but tumor cells often extend beyond 1.5 cm of the enhanced ring. Nonenhancing center may represent necrosis or associated cyst.
• On imaging, factors affecting prognosis are location (eloquent vs. non-eloquent) and tumor size

Our case: anaplastic astrocytoma.

Reference:

Greenburg MS. Handbook of neurosurgery, 7th edition, 2010.