Imaging Evaluation of Plexiform Neurofibromas in Neurofibromatosis Type 1: A Survey-Based Assessment.

OBJECTIVE: To assess imaging utilization practices across clinical specialists in neurofibromatosis type 1 (NF1) for the evaluation of symptomatic and asymptomatic children and adults with or without plexiform neurofibromas (PN). METHODS: An institutional review board-exempt survey was administered to medical practitioners caring for individuals with NF1 at the Response Evaluation in Neurofibromatosis and Schwannomatosis (REiNS) meeting in September 2019. The survey included questions on respondent demographic data (9 questions), type of imaging obtained for asymptomatic (4 questions) and symptomatic (4 questions) people with and without PN, and utilization of diffusion-weighted imaging (2 questions). RESULTS: Thirty practitioners participated in the survey. Most were academic neuro-oncologists at high-volume (>10 patients/week) NF1 centers. Of 30 respondents, 26 had access to whole-body MRI (WB-MRI). The most common approach to an asymptomatic person without PN was no imaging (adults: 57% [17/30]; children: 50% [15/30]), followed by a screening WB-MRI (adults: 20% [6/30]; children: 26.7% [8/30]). The most common approach to a person with symptoms or known PN was regional MRI (adults: 90% [27/30]; children: 93% [28/30]), followed by WB-MRI (adults: 20% [6/30]; children: 36.7% [11/30]). WB-MRI was most often obtained to evaluate a symptomatic child with PN (37% [11/30]). CONCLUSIONS: More than 90% of practitioners indicated they would obtain a regional MRI in a symptomatic patient without known or visible PN. Otherwise, there was little consensus on imaging practices. Given the high prevalence of PN and risk of malignant conversion in this patient population, there is a need to define imaging-based guidelines for optimal clinical care and the design of future clinical trials.

The Value of Quantitative Musculoskeletal Imaging.

Musculoskeletal imaging is mainly based on the subjective and qualitative analysis of imaging examinations. However, integration of quantitative assessment of imaging data could increase the value of imaging in both research and clinical practice. Some imaging modalities, such as perfusion magnetic resonance imaging (MRI), diffusion MRI, or T2 mapping, are intrinsically quantitative. But conventional morphological imaging can also be analyzed through the quantification of various parameters. The quantitative data retrieved from imaging examinations can serve as biomarkers and be used to support diagnosis, determine patient prognosis, or monitor therapy.We focus on the value, or clinical utility, of quantitative imaging in the musculoskeletal field. There is currently a trend to move from volume- to value-based payments. This review contains definitions and examines the role that quantitative imaging may play in the implementation of value-based health care. The influence of artificial intelligence on the value of quantitative musculoskeletal imaging is also discussed.

International Society for the Study of Vascular Anomalies Classification of Soft Tissue Vascular Anomalies: Survey-Based Assessment of Musculoskeletal Radiologists' Use in Clinical Practice.

AIM: There is controversy regarding the diagnosis and classification of vascular anomalies (VA). As torso and extremities are the second most common body part for presentation of VAs, musculoskeletal (MSK) radiologists play a central role in VA classification. The purpose of this study was to evaluate the awareness and clinical use of the International Society for the Study of Vascular Anomalies (ISSVA) classification by MSK radiologists. MATERIALS AND METHODS: A Web-based survey was designed and electronically sent to Society of Skeletal Radiology (SSR) members, with 3 questions on demographics and 7 questions on ISSVA classification use and knowledge. The Z-test for binomial proportions is used to assess for statistical significance between subgroups. RESULTS: The response rate was 12% (130 of 1091), comprised of 64% (83 of 130) academic and 36% (47 of 130) nonacademic MSK radiologists. VAs accounted for only a small (0%-5%) proportion of clinical practice in the majority 92% (119 of 130). Only 17% (22 of 130) of MSK radiologists used the ISSVA classification in practice. Of all respondents, 74% (94 of 127) considered hemangioma a type of vascular malformation (VM). There was no significant difference in the response characteristics between academic and nonacademic radiologists. A greater proportion of MSK radiologists with >5 years' experience provided responses that were discordant with the ISSVA classification compared with less experienced radiologists (0-5 years) in diagnosing hemangiomas in adult patients (P = 0.02), and using the presence of phleboliths to diagnose hemangiomas (P = 0.004). CONCLUSION: Our survey results indicate a lack of familiarity with the ISSVA classification by the MSK radiology community.

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.

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). CONCLUSION: 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.

Multiparametric Assessment of Treatment Response in High-Grade Soft-Tissue Sarcomas with Anatomic and Functional MR Imaging Sequences.

PURPOSE: To determine the added value of quantitative diffusion-weighted and dynamic contrast material-enhanced imaging to conventional magnetic resonance (MR) imaging for assessment of the response of soft-tissue sarcomas to neoadjuvant therapy. MATERIALS AND METHODS: MR imaging examinations in 23 patients with soft-tissue sarcomas who had undergone neoadjuvant therapy were reviewed by two readers during three sessions: conventional imaging (T1-weighted, fluid-sensitive, static postcontrast T1-weighted), conventional with diffusion-weighted imaging, and conventional with diffusion-weighted and dynamic contrast-enhanced imaging. For each session, readers recorded imaging features and determined treatment response. Interobserver agreement was assessed and receiver operating characteristic analysis was performed to evaluate the accuracy of each session for determining response by using results of the histologic analysis as the reference standard. Good response was defined as less than or equal to 5% residual viable tumor. RESULTS: Of the 23 sarcomas, four (17.4%) showed good histologic response (three of four with >95% granulation tissue and <5% necrosis, one of four with 95% necrosis and <5% viable tumor) and 19 (82.6%) showed poor response (viable tumor range, 10%-100%). Interobserver agreement was substantial or excellent for imaging features in all sequences (k = 0.789-1.000). Receiver operating characteristic analysis showed an increase in diagnostic performance with the addition of diffusion-weighted and dynamic contrast-enhanced MR imaging for prediction of response compared with that for conventional imaging alone (areas under the curve, 0.500, 0.676, 0.821 [reader 1] and 0.506, 0.704, 0.833 [reader 2], respectively). CONCLUSION: Adding functional sequences to the conventional MR imaging protocol increases the sensitivity of MR imaging for determining treatment response in soft-tissue sarcomas.

De Novo Assessment of Pediatric Musculoskeletal Soft Tissue Tumors: Beyond Anatomic Imaging.

MRI plays a central role in the assessment of pediatric musculoskeletal soft tissue tumors. Although these neoplasms may initially be evaluated on other modalities, such as sonography, MRI is essential for accurately determining the extent of disease. Traditionally, MRI has been performed with sequences that provide excellent anatomic detail, with T1-weighted, fluid-sensitive, and static postcontrast T1-weighted sequences. However, with the introduction of noncontrast sequences such as diffusion-weighted imaging and magnetic resonance spectroscopy to the arsenal of available MRI techniques, functional and metabolic features of a neoplasm can now be examined noninvasively. These more recent MRI methods offer information for lesion characterization, the assessment of treatment response, and the distinction of postoperative scar from recurrence. Dynamic contrast-enhanced perfusion imaging is another useful functional technique that can be acquired before conventional static postcontrast imaging, without requiring additional contrast material. This review presents recent advances in MRI methodology that enable a comprehensive clinical assessment of musculoskeletal tumors in the pediatric population. The roles and challenges of combining anatomic, functional, and metabolic MRI sequences will be discussed as they relate to newly discovered soft tissue tumors in children.

Proton MR spectroscopy in metabolic assessment of musculoskeletal lesions.

OBJECTIVE: The purposes of this review are to describe the principles and method of MR spectroscopy, summarize current published data on musculoskeletal lesions, and report additional cases that have been analyzed with recently developed quantitative methods. CONCLUSION: Proton MR spectroscopy can be used to identify key tissue metabolites and may serve as a useful adjunct to radiographic evaluation of musculoskeletal lesions. A pooled analysis of 122 musculoskeletal tumors revealed that a discrete choline peak has a sensitivity of 88% and specificity of 68% in the detection of malignancy. Modest improvements in diagnostic accuracy in 22 of 122 cases when absolute choline quantification was used encourage the pursuit of development of choline quantification methods.

Recognition, assessment, and treatment of non-union after surgical fixation of fractures: emphasis on 3D CT.

For the post-operative patient, conventional axial computed tomography (CT) imaging and 2D multiplanar reconstruction are of limited value because of the beam-hardening artifact. However, three-dimensional (3D) CT imaging is an effective means of detecting subtle fracture healing, or confirming non-union, and for evaluating the integrity of metal hardware. In this article we emphasize the advantages of 3D CT imaging in the assessment and preoperative planning of non-union for patients who have been surgically treated for fractures.