Wednesday, 27 June 2012


64 yrs female with painless hard lump in left breast with nipple retraction

Irregular retroareolar mass lesion with gross spiculations extending radially deep into the breast parenchyma with thickening and induration of surrounding skin and subcutaneous planes.
                                                               Nipple is retracted.

Signs of malignancy on mammogram are divided into major signs (conventional signs) and supporting signs (indirect signs).
Major Signs:

1.     Spiculated Margins: 
·        Spiculated margins are a true diagnostic feature of malignancy.
·        Strands of tissue are seen radiating out from an ill-defined mass, producing a stellate appearance.
·        This appearance is pathognomonic of breast cancer.
·        Spiculation represent retraction of tissue strands towards the tumor due to fibrosis - as a result of desmoplastic response.
·        Sometimes, only the spiculation are seen without a mass

2.     Clustered Microcalcifications:
·        Mammography is the only technique capable of detecting microcalcification Microcalcification, even when found in isolation herald the presence of early stage breast cancer.
·        Five or more calcifications, measuring less than 1mm, in a volume of one cubic centimeter, define a 'cluster'.
·        The possibility of malignancy increases as the size of individual calcification decreases, the total number of calcification per limit area increases.
·        It is the distribution and morphology of the calcifications, which defines their significance.

Supporting Signs of Malignancy
These indirect signs, though non-specific, signify enough risk to warrant intervention.
1.     Poorly Defined Mass
·        Most breast cancers are seen as poorly defined masses, without any mammographic features more suggestive of malignancy.
·        Circumscribed masses with margins that are mostly well defined with only a portion ill-defined, are also managed as other ill-defined masses.
·        There are a sizable number of benign breast masses whose margin appears to be poorly defined, and therefore are difficult to differentiate from malignancy resulting in the need to biopsy in order to detect early cancer.

2.     Microlobulation
·        Lobulations are usually associated with fibroadenomas.
·        Increased number of lobulations, measuring few millimeters should be suspected for malignancy.

3.     Architectural Distortion
·        Breast cancer does not always produce a mammographically visible mass.
·        Sometimes it produces just a localized cicatrization.
·        If previous surgery and trauma to the breast can be excluded, there is high likelihood that the distortion is because of malignancy.
·        Invasive carcinoma distorts the interface between breast and normal parenchyma due to desmoplastic response of host tissue to the malignancy.

4.     Asymmetric Density
·        Asymmetric density is the three dimensional area in which the density is greatest at the centre and fades towards the periphery trying to form a mass.
·        In this situation, it is helpful to to view the mammograms of both breasts side by side.

5.     Nipple Retraction
·        Nipple retraction "over a short period of time" is suspicious of an underlying cancer.

6.     Enlarged Axillary Lymph nodes
·        Demonstration of large nodes is non-specific sign of malignancy.
·        Involvement of the nodes(s) indicates worsening of prognosis.

BI-RADS  Category
Clinical Management Recommendation(s)

Assessment incomplete
Need to review prior studies and/or complete additional imaging

Continue routine screening

Benign finding
Continue routine screening

Probably benign finding
Short-term follow-up mammogram at 6 months, then every 6 to 12 months for 1 to 2 years

Suspicious abnormality
Perform biopsy, preferably needle biopsy

Highly suspicious of malignancy; appropriate action should be taken.
Biopsy and treatment, as necessary.

Known biopsy-proven malignancy, treatment pending
Assure that treatment is completed

Thursday, 21 June 2012


85 yrs male with history of fall
Axial plain CT section through pancreas: well defined airpocket with adjacent solid debris noted potero medial to head of pancreas (coronal reformation showed this as outpouching from 3rd part of duodenum)- s/o incidental duodenal diverticulum.

·        Duodenal diverticula are common and are incidentally discovered.
·        Most are acquired, rather than congenital, abnormalities.
·        Easily recognized on upper gastrointestinal barium examinations as collections of gas and barium in round or oval sacklike protrusions that usually arise from the medial aspect of the periampullary duodenum.
·        The typical CT appearance of a duodenal diverticulum has been described as a thin-walled rounded collection of gas and oral contrast material situated along the medial border of the junction of the second and third portions of the duodenum.
·        On T2-weighted MR imaging, duodenal diverticula may contain both high-signal-intensity areas (related to the presence of fluid) and low-signal-intensity areas (related to the presence of gas).
·        Duodenal diverticula are rarely symptomatic, although they may make cannulation of the common bile duct difficult during an ERCP or may become impacted with debris, leading to duodenal diverticulitis.
·        Complications of hemorrhage and increased prevalence of choledocholithiasis have been described.
·        Misinterpretation of a duodenal diverticulum on CT as a pancreatic tumor, metastatic lymph node, pancreatic pseudocyst, or pancreatic abscess has been reported.
·        One may be unable to distinguish duodenal diverticula on CT or MR imaging if their content is purely fluid.
·        The differential diagnosis of a cystic lesion in the region of the head of the pancreas includes cystic pancreatic neoplasms, inflammatory processes (such as pseudocysts), and duodenal diverticula.
·        Three cystic tumors are relatively common pancreatic neoplasms—an intraductal papillary mucinous neoplasm, mucinous cystic neoplasm, and serous cystic neoplasm.
Reference: Duodenal Diverticula Mimicking Cystic Neoplasms of the Pancreas: CT and MR Imaging Findings in Seven Patients, AJR January 2003 vol. 180 no. 1 195-199.


2 months baby with a large meningocele

Sagittal T2 images revealed small posterior fossa with herniation of elongated cerebellar tonsil.
Large meningomyelocele in the lumbar region with a neural placode within it.
Axial T2 image of brain showed dilated atrium and occipital horn of left ventricle- s/o colpocephaly.

•Chiari I malformation
  • most common
  • peg-like cerebellar tonsils displaced into the upper cervical canal through the foramen magnum
•Chiari II malformation
  • displacement of the medulla, fourth ventricle and cerebellum through the foramen magnum
  • usually with associated with a lumbosacral spinal myelomeningocoele
•Chiari III malformation
  • features similar to Chiari II  but with an occipital and / or high cervical encephalocoele
•Chiari IV malformation
  • severe cerebellar hypolasia without displacement of the cerebellum through the foramen magnum
  • probably a variation of cerebellar hypoplasia
Arnold chiari type II malformation:
  • Usually accompanied by a lumbar myelomeningocele leading to partial or complete paralysis below the spinal defect.  
  • As opposed to the less pronounced tonsillar herniation seen with Chiari I, there is a larger cerebellar vermian displacement.
  • Low lying torcular herophili, tectal beaking, and hydrocephalus with consequent clival hypoplasia are classic anatomic associations.
  • The position of the torcular herophili is important for distinction from Dandy-Walker syndrome in which it is classically upturned.
  •  This is important because the hypoplastic cerebellum of Dandy-Walker may be difficult to distinguish from a Chiari malformation that has herniated or is ectopic on imaging.
  • Colpocephaly may be seen due to the associated neural tube defect.
Reference : Pediatric brain and spine, an atlas of MRI and spectroscopy. Springer Verlag. (2005) ISBN:3540213406

Wednesday, 20 June 2012



Fusiform dilatation of common hepatic duct and proximal common bile duct with multiple stones within it- s/o type I choledochal cyst with choledocholithiasis. Edema of gall bladder wall- s/o cholecystitis

·        The widely accepted classification system for choledochal cysts, which was devised by Todani et al is based on the cholangiographic morphology, location, and number of intrahepatic and extrahepatic bile duct cysts.
·        Type I cysts are confined to the extrahepatic bile duct (EHD) and can be further subdivided into IA, IB and IC
·        IA cyst involves the entire EHD, IB involves only a focal segment of the EHD, and IC involves only the CBD.
·        Type II cysts are true diverticula of the EHD.
·        Type III cysts are also referred to as choledochocele and are confined to the EHD within the duodenal wall.
·        Type IV cysts have multiple features which can include both an extrahepatic and intrahepatic component.
·        Type IV cysts can be further subdivided into type IVA involving both the EHD and intrahepatic bile duct, as well as type IVB, involving multiple segmental dilatations of the EHD.
·        Type V (Calori's disease) cysts are confined to the IHD
·        Complications :
1.     Cholecystitis
2.     Recurrent cholangitis
3.     Biliary stricture
4.     Choledocholithiasis
5.     Recurrent acute pancreatitis
6.     Malignant transformation into cholangiocarcinoma

Imaging Features of Adult Choledochal Cysts: a Pictorial Review, Korean J Radiol. 2009 Jan-Feb; 10(1): 71–80.

Tuesday, 19 June 2012


Large cystic lesion in left cerebellar hemisphere extending into the vermis with mild left tonsillar herniation. Post contrast there is intense homogenous enhancement of the eccentric mural nodule situated towards the vermis. Cyst wall didnot show any enhancement.

·        Four predominant imaging patterns of pilocytic astrocytoma have been described:
1.     Mass with a nonenhancing cyst and an intensely enhancing mural nodule
2.     Mass with an enhancing cyst wall and an intensely enhancing mural nodule
3.     Necrotic mass with a central nonenhancing zone
4.     Predominantly solid mass with minimal to no cystlike component
·        Hence, two-thirds of all cases demonstrate the classic imaging manifestation of a cystlike mass with an enhancing mural nodule.
·        Although most cyst walls do not enhance, some may enhance intensely, even as much as the mural nodule.
·        Differential diagnosis : hemangioblastoma
Hypoattenuating cystic componenet with hypo to isoattenuating mural nodule with avid contrast enhancement
Hypoattenuating cyst and isodense nodule with avid contrast enhancement
Well demarcated lesion
Well demarcated lesion
Solid component: iso to hypointense relative to normal brain
Nodule peripherally located near pial surface and isointense to gray matter on T1
Cystic component follows fluid signal intensity
Iso or slightly hyperintense on T1 compared with CSF
Nodule: hyperintense with minimal surrounding T2WI signal
Nodule : hyperintense
Cyst follows fluid signal
High signal intensity
Avid enhancement of mural nodule
Avid enhancement of solid component
No reported abnormal flow voids
Peripheral in location due to vascular supply from pia mater with nodule located near pial surface. May see abnormal vessels/ flow voids
Low signal on DWI and high on ADC
Low signal on DWI and high on ADC
Rarely calcifies
May bleed into cyst leading to fluid levels
Rarely hemorrhage into the nodule or into subarachnoid space
If hemorrhage into nodule, appearance depends on age of hemorrhage

References :
1.     Pilocytic Astrocytoma: Radiologic-Pathologic Correlation, November 2004 RadioGraphics, 24
2.     Practical differential diagnosis for CT and MRI.