• Shivani Ahlawat, Carol Morris, and Laura M Fayad.
• The Russell H. Morgan Department of Radiology & Radiological Science, The Johns Hopkins Medical Institutions, 600 North Wolfe Street, Baltimore, MD, 21287, USA. sahlawa1@jhmi.edu.
• Skeletal Radiol. 2016 May 1; 45 (5): 645-52.

BackgroundTo assess the acquisition speed, lesion conspicuity, and inter-observer agreement associated with volumetric T(1)-weighted MR sequences with isotropic resolution for detecting recurrent soft-tissue sarcoma (STS).MethodsFifteen subjects with histologically proven recurrent STS underwent MRI, including axial and coronal T(1)-weighted spin echo (T(1)-WSE) (5-mm slice thickness) and coronal 3D volumetric T(1)-weighted (fat-suppressed, volume-interpolated, breath-hold examination; repetition time/echo time, 3.7/1.4 ms; flip angle, 9.5°; 1-mm slice thickness) sequences before and after intravenous contrast administration. Subtraction imaging and multiplanar reformations (MPRs) were performed. Acquisition times for T(1)-WSE in two planes and 3D sequences were reported. Two radiologists reviewed images for quality (>50 % artifacts, 25-50 % artifacts, <25 % artifacts, and no substantial artifacts), lesion conspicuity, contrast-to-noise ratio (CNR(muscle)), recurrence size, and recurrence-to-joint distance. Descriptive and intraclass correlation (ICC) statistics are given.ResultsMean acquisition times were significantly less for 3D imaging compared with 2-plane T(1)-WSE (183.6 vs 342.6 s; P = 0.012). Image quality was rated as having no substantial artifacts in 13/15 and <25 % artifacts in 2/15. Lesion conspicuity was significantly improved for subtracted versus unsubtracted images (CNR(muscle), 100 ± 138 vs 181 ± 199; P = 0.05). Mean recurrent lesion size was 2.5 cm (range, 0.7-5.7 cm), and measurements on 3D sequences offered excellent interobserver agreement (ICC, 0.98 for lesion size and 0.96 for recurrence-to-joint distance with MPR views).ConclusionThree-dimensional volumetric sequences offer faster acquisition times, higher spatial resolution, and MPR capability compared with 2D T(1)-WSE for postcontrast imaging. Subtraction imaging provides higher lesion conspicuity for detecting recurrent STS in skeletal muscle, with excellent interobserver agreement between readers.

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