Answer for CoW 27 November 2016
Lipid Poor Adrenal Adenoma
Findings
The present study was a folllowup , two years after the lesion was first detected . Focal Nodular lesion noted within the right adrenal Gland . It appears hyperintense in the In Phase Images without signal drop off in Opposed Phase images . The lesion does not exhibit contrast enhancement , nor does it show restricted diffusion .The ADC values were 1.5 x 10-3. The above features denote a Lipid Poor Adenoma.
Discussion
Approximately 80% of all adenomas can be diagnosed by chemical-shift MRI alone because adenomas are generally 70% lipid-rich (≤ 10 HU) and 30% lipid-poor (> 10 HU). All lipid-poor adenomas measuring 20 HU or less on unenhanced CT can be correctly characterized by chemical-shift MRI. Lipid Rich Adenomas show signal suppression in Opposed Phase Images . Diffusion weighted Imaging with ADC values are used to characterize tumors or granulomas . Lesions that are indeterminate on adrenal signal intensity index and that have an ADC value of more than 1.5 × 10−3 mm2/s may be considered benign. Lesions that are indeterminate on quantitative chemical shift imaging and that have an ADC value of less than 1.0 × 10−3 mm2/s are likely to be malignant. The adrenal-to-spleen ratio (ASR) was calculated as ASR = (SIAO / SISO) / (SIAI / SISI). SIAO was the signal intensity of the adrenal mass on opposed-phase images, SISO was the signal intensity of the spleen on opposed-phase images, SIAI was the signal intensity of the adrenal mass on in-phase images, and SISI was the signal intensity of the spleen on in-phase images. The signal intensity index (SII) was calculated as SII = (SIAI − SIAO)·100 / SIAI. The signal intensity index (SII) threshold of 11.2–16.5% had MRI accuracy of 100% and was the best parameter for distinguishing adenomas from metastatic tumors.
Ref: 1.Characterization of Lipid-Poor Adrenal Adenoma: Chemical-Shift MRI and Washout CT Jung Min Seo1, Byung Kwan Park1Sung Yoon Park AJR May 2014, Volume 202, Number 5 2.Characterization of Adrenal Masses With Diffusion-Weighted Imaging Kumaresan Sandrasegaran1 Aashish A. Patel1 AJR 2011; 197:132–138
Findings
The present study was a folllowup , two years after the lesion was first detected . Focal Nodular lesion noted within the right adrenal Gland . It appears hyperintense in the In Phase Images without signal drop off in Opposed Phase images . The lesion does not exhibit contrast enhancement , nor does it show restricted diffusion .The ADC values were 1.5 x 10-3. The above features denote a Lipid Poor Adenoma.
Discussion
Approximately 80% of all adenomas can be diagnosed by chemical-shift MRI alone because adenomas are generally 70% lipid-rich (≤ 10 HU) and 30% lipid-poor (> 10 HU). All lipid-poor adenomas measuring 20 HU or less on unenhanced CT can be correctly characterized by chemical-shift MRI. Lipid Rich Adenomas show signal suppression in Opposed Phase Images . Diffusion weighted Imaging with ADC values are used to characterize tumors or granulomas . Lesions that are indeterminate on adrenal signal intensity index and that have an ADC value of more than 1.5 × 10−3 mm2/s may be considered benign. Lesions that are indeterminate on quantitative chemical shift imaging and that have an ADC value of less than 1.0 × 10−3 mm2/s are likely to be malignant. The adrenal-to-spleen ratio (ASR) was calculated as ASR = (SIAO / SISO) / (SIAI / SISI). SIAO was the signal intensity of the adrenal mass on opposed-phase images, SISO was the signal intensity of the spleen on opposed-phase images, SIAI was the signal intensity of the adrenal mass on in-phase images, and SISI was the signal intensity of the spleen on in-phase images. The signal intensity index (SII) was calculated as SII = (SIAI − SIAO)·100 / SIAI. The signal intensity index (SII) threshold of 11.2–16.5% had MRI accuracy of 100% and was the best parameter for distinguishing adenomas from metastatic tumors.
Ref: 1.Characterization of Lipid-Poor Adrenal Adenoma: Chemical-Shift MRI and Washout CT Jung Min Seo1, Byung Kwan Park1Sung Yoon Park AJR May 2014, Volume 202, Number 5 2.Characterization of Adrenal Masses With Diffusion-Weighted Imaging Kumaresan Sandrasegaran1 Aashish A. Patel1 AJR 2011; 197:132–138
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!