Whole-body MRI of multiple myeloma: Comparison of different MRI sequences in assessment of different growth patterns

Purpose: To determine sensitivity, specificity and inter-observer variability of different whole-body MRI (WB-MRI) sequences in patients with multiple myeloma (MM). Methods and materials: WB-MRI using a 1.5 T MRI scanner was performed in 23 consecutive patients (13 males, 10 females; mean age 63 ± 12 years) with histologically proven MM. All patients were clinically classified according to infiltration (low-grade, n = 7; intermediate-grade, n = 7; high-grade, n = 9) and to the staging system of Durie and Salmon PLUS (stage I, n = 12; stage II, n = 4; stage III, n = 7). The control group consisted of 36 individuals without malignancy (25 males, 11 females; mean age 57 ± 13 years). Two observers independently evaluated the following WB-MRI sequences: T1w-TSE (T1), T2w-TIRM (T2), and the combination of both sequences, including a contrast-enhanced T1w-TSE with fat-saturation (T1 ± CE/T2). They had to determine growth patterns (focal and/or diffuse) and the MRI sequence that provided the highest confidence level in depicting the MM lesions. Results were calculated on a per-patient basis. Results: Visual detection of MM was as follows: T1, 65% (sensitivity)/85% (specificity); T2, 76%/81%; T1 ± CE/T2, 67%/88%. Inter-observer variability was as follows: T1, 0.3; T2, 0.55; T1 ± CE/T2, 0.55. Sensitivity improved depending on infiltration grade (T1: 1 = 60%; 2 = 36%; 3 = 83%; T2: 1 = 70%; 2 = 71%; 3 = 89%; T1 ± CE/T2: 1 = 50%; 2 = 50%; 3 = 89%) and clinical stage (T1: 1 = 58%; 2 = 63%; 3 = 79%; T2: 1 = 58%; 2 = 88%; 3 = 100%; T1 ± CE/T2: 1 = 50%; 2 = 63%; 3 = 100%). T2w-TIRM sequences achieved the best reliability in depicting the MM lesions (65% in the mean of both readers). Conclusions: T2w-TIRM sequences achieved the highest level of sensitivity and best reliability, and thus might be valuable for initial assessment of MM. For an exact staging and grading the examination protocol should encompass unenhanced and enhanced T1w-MRI sequences, in addition to T2w-TIRM