Monday, 16 November 2015

xrayoftheweek 46: another example of diffusion weighted imaging

The #xrayoftheweek is this panel of CT and MRI images in someone with a known past gynaecologic malignancy and now presenting with upper abdominal pain and vomiting. 

The images are as follows:
a & b: axial contrast-enhanced CT images from the upper abdomen
c & d: diffusion weight sequence (b=800) in same slice position as a & b
e & f: apparent diffusion coefficient (ADC) map of slices c & d

Which imaging signs can you see on these images and what do they mean? Why is this person vomiting?
The red arrows on these images point to multiple peritoneal and mesenteric malignant deposits. In images a, c and e, these can be seen indenting, or "scalloping" the surface of the liver (subcapsular deposits). The diffusion weighted imaging indicates that there is restriction of diffusion and tells us that there is high cellularity in these lesions. In images b, d and f, there is a lesion with similar characteristics very close to the body of the stomach - this particular lesion was compressing the stomach and causing gastric outlet obstruction, which is why this person was vomiting. 

In this case, the CT and structural MR images told us that there was widespread metastatic peritoneal disease - I am showing you the diffusion images to illustrate how well the sequence can pick up malignant tissue, and has the potential to track response to treatment by looking for changes in the ADC value.

My other #xrayoftheweek case involving diffusion weighted imaging can all be found here, and an introduction to the technique and an explanation of the image below can be found here.

#FOAMrad #FOAMed