title: Three-dimensional volumetric MRI with isotropic resolution: improved speed of acquisition, spatial resolution and assessment of lesion conspicuity in patients with recurrent soft tissue sarcoma.
abstract: BACKGROUND
  To 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).
  
  
  METHODS
  Fifteen 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.
  
  
  RESULTS
  Mean 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).
  
  
  CONCLUSIONS
  Three-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.
authors.affiliation: 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.
authors.forename: Shivani
authors.initials: S
authors.lastname: Ahlawat
authors.affiliation: Department of Orthopedic Surgery, The Johns Hopkins Medical Institutions, 601 North Caroline Street, Baltimore, MD, 21287, USA.|Department of Oncology, The Johns Hopkins Medical Institutions, 601 North Caroline Street, Baltimore, MD, 21287, USA.
authors.forename: Carol
authors.initials: C
authors.lastname: Morris
authors.affiliation: The Russell H. Morgan Department of Radiology & Radiological Science, The Johns Hopkins Medical Institutions, 600 North Wolfe Street, Baltimore, MD, 21287, USA.|Department of Orthopedic Surgery, The Johns Hopkins Medical Institutions, 601 North Caroline Street, Baltimore, MD, 21287, USA.|Department of Oncology, The Johns Hopkins Medical Institutions, 601 North Caroline Street, Baltimore, MD, 21287, USA.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Fayad
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016880:Anisotropy; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012509:Sarcoma / Q000000981:diagnostic imaging* / Q000473:pathology; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D047368:Tumor Burden; D055815:Young Adult
keywords: 3D volumetric MR sequences; Recurrent soft-tissue sarcoma; Subtraction imaging