RadiologySpirit

Wednesday, March 30, 2011

ADC map differentiation between tumoral and non tumoral tissue

ADC MAP DIFFERENTIATION BETWEEN TUMORAL AND NON TUMORAL TISSUE: -With high cellularity lesion , has a low ADC map value resulting in hypo intense signal. -While in low cellularity lesion such as edema , inflammation , fibrosis , and necrosis shows high ADC map signal.

CT image of biopsy proven case of squamous cell carcinoma of left tonsil. http://sumerdoc.blogspot.com/2009/07/carcinoma-tonsil-ct.html

Thursday, February 24, 2011

Hemangioma

Vertebral body hemangiomas are the most common tumors of the spinal axis and in most circumstances are incidental findings. Most hemangiomas are diagnosed based on their characteristic imaging findings, though the diagnosis can be challenging in cases of atypical or aggressive hemangiomas. In such cases, the recognition of vertically oriented coarse bony trabeculae surrounded by fatty stroma, resulting in the "salt and pepper" appearance on axial images and a striated appearance on coronal or sagittal images, is the key to the correct diagnosis. Though rare, aggressive hemangiomas can be symptomatic and pathologic fractures can lead to myelopathy and cord compression. In such patients, MR accurately displays the extraosseous extension of the hemangioma and its effect upon the spinal canal and cord.

Atypical hemangioma

The T1-weighted sagittal image demonstrates an atypical hemangioma within the L1 vertebral body (arrow) with coarse trabeculae, but with relatively little typical fat signal within the lesion.

The T2-weighted sagittal image shows a typical appearance with increased signal intensity, well-circumscribed margins and coarsened trabeculae (arrow).

http://www.radsource.us/clinic/0611

Typical hemangioma

The T2-weighted sagittal image shows a lesion of increased signal intensity replacing the entire L2 vertebral body. Coarse vertically oriented trabeculae are present (arrows).

The T1-weighted sagittal image reveals that the L2 vertebral body lesion (arrow) is of increased signal intensity, similar to that seen on the T2-weighted image.

The T1-weighted axial image demonstrates the coarse trabeculae on end surrounded by fat signal, resulting in a 'salt and pepper" appearance (arrow).

On plain radiographs, hemangiomas often have a vertically striated appearance due to thickening of bony trabeculae. This appearance has been described as "corduroy cloth" or "jail bar" and the overall density of the vertebral body is decreased due to the presence of fatty marrow.

With CT, vertebral body hemangiomas have low attenuation interspersed with thickened bony trabeculae, causing a characteristic "salt and pepper" or "polka dot" appearance on axial images.

With MR imaging, the intralesional fat of the hemangioma causes increased signal intensity on T1 weighted MR images.4 On T2-weighted images, the signal intensity of the hemangiomas also increases because of high water content,4 and the T2-hyperintensity is typically greater than that of fat, thereby differentiating hemangiomas from focal fat deposition.
These signal characteristics also differ from those of metastatic lesions, which have decreased signal intensity on T1 weighted images and increased signal intensity on T2 weighted images.