Purpose or Case Report: To determine if a 3-minute Golden-angle RAdial Sparse Parallel (GRASP) dynamic contrast enhanced (DCE) MRI sequence with 8-10 second temporal resolution is equivalent in diagnostic performance to a conventional MR sequences (CS) in the assessment of osteomyelitis (OM) in children.

Methods & Materials: 6 subjects (9m – 23y) with suspected OM were imaged at 3T as part of an IRB-approved study. The scans included both conventional sequences (T1, IR, PD, T2-weighted and T1 fat suppressed postcontrast) for osteomyelitis as well as a 3-minute GRASP DCE sequence that we have been concurrently evaluating in a sheep model. CS were interpreted per clinical standards. GRASP was interpreted independently by 3 radiologists, blinded to CS, and scored with binary (y/n) answers for reporting elements in OM including marrow signal abnormality, synovitis, subperiosteal abscess, intraosseous abscess, soft tissue or muscle hypoenhancement, myositis, and cellulitis.
Results: Average total exam time for CS protocol was 46.2 ± 15.1 minutes. Average additional time for GRASP was 8 ± 5.1 minutes including prescription and scanning. Average slice thickness was 3.2 mm for CS and 1.5 mm for GRASP. CS demonstrated marrow signal abnormality in 4 of 6 cases, attributed to OM in 3, with one case being posttraumatic. Synovitis (n=3), soft tissue hypoenhancement (n=3), myositis (n=2), and cellulitis (n=4) were also identified. There were no cases of intraosseous or subperiosteal abscess. Based on the average sensitivity and specificity of the 3 readers, GRASP was relatively sensitive (83%) and highly specific (100%) in detection of marrow signal abnormality, highly sensitive (100%) and specific (89%) for soft tissue or muscle hypoenhancement, and 100% sensitive and 67% specific for cellulitis. GRASP was less sensitive than CS for detection of synovitis (50%) and myositis (50%), with high specificity (100% and 92% respectively). Locations of disease were concordant across readers and consistent with CS.

Conclusions: Based on preliminary data in this ongoing study, GRASP holds promise for replacing CS in the diagnosis of OM and ultimately reducing sedation. Further analysis is necessary to determine if the addition of a single precontrast fluid sensitive sequence and quantitative DCE curves may provide additional diagnostic benefit.