59-year-old male with a history of prostate cancer with Hx of osteomyelitis of the sacrum and pelvic abscess anterior to S1joint 15mm seen in previous MRI done 01/21/16. MRI of the pelvis reveals increased STIR signal abnormality and enhancement involving the lateral left sacrum, left sacroiliac joint and medial left ilium which has increased in extent and signal abnormality compared to the exam dated 12/20/2016. There is corresponding T1 hypointensity involving the left lateral sacrum and medial ileum which has also increased compared to the prior exam, indicating a high likelihood of osteomyelitis. There is also an increase in the abnormal signal abnormality and enhancement involving the left gluteus muscles and the iliopsoas muscle within the pelvis just anterior to the medial ileum is a small heterogeneous fluid collection which measures 1.6 x 2.0 cm (series 801, image 32) appears more pronounced. This location also demonstrates restricted diffusion on DWI imaging indicating further evidence of abscess formation.
1.Enhancement of the left sacroiliac joint with T1 hypointense and T2 hyperintense lateral sacrum and medial ileum highly suspicious for osteomyelitis.2.1.6 x 2.0 cm heterogeneous peripherally enhancing fluid collection just anterior to the left sacroiliac joint compatible with an abscess, which has increased compared to the prior exam.3.Enhancement and edema involving the gluteal and iliopsoas musculature indicating extension of the inflammation/infection into the adjacent soft tissues.