RSNA 2017: 5-minute knee MRI exam = standard knee MRI

A 5-minute knee magnetic resonance imaging protocol with parallel imaging is comparable to a standard knee MRI protocol, according to a study comparing the two that was conducted at New York University. Study results showed that the imaging results were diagnostically interchangeable and that the 5-minute knee MR images produced similar accuracy to a standard knee MRI for evaluating internal derangement of the knee.

The patient cohort consisted of 100 patients who had standard protocol knee MRI exams using a 3T modality and 46 patients who had 50 1.5T rapid protocol exams. The exams of the 46 patients consisted of 5 fast multiplanar 2D FSE sequences using parallel imaging and 5 standard sequences. The 150 exams were retrospectively reviewed by four musculoskeletal radiologists.

The radiologists compared menisci, ligaments, cartilage, and bone to determine interchangeability. They also made additional comparisons between the rapid- and standard- protocol exams with respect to frequency of major findings. Sensitivity and specificity were also compared and significant differences were tested for 51 patients who had surgical knee procedures.

Session presenter Erin F. Alaia, MD, a musculoskeletal radiologist at NYU Langone Health in New York City, reported that interreader agreement was similar for both protocols. The frequency of major findings was not significantly different either. However, more cartilage defects were reported on standard MRI; fast MRI was slightly less sensitive.  More ACL tears were report on the fast MRI scans. Overall, sensitivities and specificities were not significantly different.

Dr. Alaia said that a MRI exam using a fast protocol has the potential to increase throughput, to improve image quality by decreasing motion artifacts, and to increase the comfort of patients, especially those who are claustrophobic.