Reason: pelvic abscess progression History: pelvic abscess Again seen is increased signal intensity within the left sacroiliac joint on T2-weighted images with enhancement of the joint following contrast administration compatible with the suspected history of infection. There is edema and enhancement within the adjacent left ilium and left sacrum. There are small erosions along the iliac and sacral margins of the joint appearing similar to the prior study when accounting for technical differences. We see no frank fluid collection either anterior or posterior to the sacroiliac joint, and overall the degree of edema and enhancement in the adjacent gluteal and iliacus musculature has decreased when compared to the prior study. There is also a focus of signal abnormality within the left sacral wing likely representing a benign bone island. There is mild enhancement along the origin of the rectus femoris which may represent a mild enthesopathy which may be of no current clinical significance.
Findings compatible with left sacroiliac joint inflammation, presumably infectious in etiology, without evidence of disease progression. Overall the degree of inflammation in the surrounding soft tissues has decreased and we see no soft tissue abscess.