MRI evaluation of soft tissue tumors: comparison of a fast, isotropic, 3D T2-weighted fat-saturated sequence with a conventional 2D T2-weighted fat-saturated sequence for tumor characteristics, resolution, and acquisition time.

OBJECTIVES: To test whether a 4-fold accelerated 3D T2-weighted (T2) CAIPIRINHA SPACE TSE sequence with isotropic voxel size is equivalent to conventional 2DT2 TSE for the evaluation of intrinsic and perilesional soft tissue tumors (STT) characteristics. METHODS: For 108 patients with histologically-proven STTs, MRI, including 3DT2 (CAIPIRINHA SPACE TSE) and 2DT2 (TSE) sequences, was performed. Two radiologists evaluated each sequence for quality (diagnostic, non-diagnostic), tumor characteristics (heterogeneity, signal intensity, margin), and the presence or absence of cortical involvement, marrow edema, and perilesional edema (PLE); tumor size and PLE extent were measured. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and acquisition times for 2DT2 in two planes and 3DT2 sequences were reported. Descriptive statistics and inter-method agreement were reported. RESULTS: Image quality was diagnostic for all sequences (100% [108/108]). No difference was observed between 3DT2 and 2DT2 tumor characteristics (p < 0.05). There was no difference in mean tumor size (3DT2: 2.9 ± 2.5 cm, 2DT2: 2.8 ± 2.6 cm, p = 0.4) or PLE extent (3DT2:0.5 ± 1.2 cm, 2DT2:0.5 ± 1.0 cm, p = 0.9) between the sequences. There was no difference in the SNR of tumors, marrow, and fat between the sequences, whereas the SNR of muscle was higher (p < 0.05) on 3DT2 than 2DT2. CNR measures on 3DT2 were similar to 2DT2 (p > 0.1). The average acquisition time was shorter for 3DT2 compared with 2DT2 (343 ± 127 s vs 475 ± 162 s, respectively). CONCLUSION: Isotropic 3DT2 MRI offers higher spatial resolution, faster acquisition times, and equivalent assessments of STT characteristics compared to conventional 2DT2 MRI in two planes. 3DT2 is interchangeable with a 2DT2 sequence in tumor protocols. KEY POINTS: • Isotropic 3DT2 CAIPIRINHA SPACE TSE offers higher spatial resolution than 2DT2 TSE and is equivalent to 2DT2 TSE for assessments of soft tissue tumor intrinsic and perilesional characteristics. • Multiplanar reformats of 3DT2 CAIPIRINHA SPACE TSE can substitute for 2DT2 TSE acquired in multiple planes, thereby reducing the acquisition time of MRI tumor protocols. • 3DT2 CAIPIRINHA SPACE TSE and 2DT2 TSE had similar CNR of tissues.

Defecation versus pre- and post-defecation Valsalva maneuvers for dynamic MR assessment of pelvic floor dysfunction.

PURPOSE: To compare prevalence and severity of multi-compartment pelvic floor dysfunction between supine magnetic resonance defecography with defecation (MRD) and supine dynamic MRI during Valsalva, both with and without rectal distention. METHODS: This was an IRB-approved, HIPAA-compliant retrospective review of consecutive patients referred for MR Defecography. MRD protocol included imaging at rest, during pre-defecation Valsalva (Pre-DV), defecation (Def), and post-defecation Valsalva (Post-DV). The Post-DV images were performed after complete evacuation either during the defecation acquisition or, in cases where patient was unable to defecate during the examination, in a conventional toilet. Size of cystocele, vaginal prolapse, anorectal (AR) descent, and enterocele were measured on all acquisitions relative to the pubococcygeal line. Rectocele size was recorded in anteroposterior dimension. The presence or absence of rectal intussusception (RI) was documented. The prevalence, absolute size, and grades of prolapse, rectocele, and RI were compared between the acquisitions using pair-wise ANOVA, Friedman, Dunn pair-wise, and Cochran-Mantel-Haenszel tests. RESULTS: 30 patients were included in the final analysis. Higher prevalence of cystocele, vaginal prolapse, enterocele, AR descent grade 2 or higher, rectocele grade 2 or higher, and RI were seen on Def compared to Post-DV and Pre-DV. Cystocele, vaginal prolapse, enterocele, AR descent, and rectocele sizes were significantly larger on Def compared to Post-DV by 0.7-1.95 cm (p ≤ 0.007). Prolapse in all compartments and rectocele size were significantly larger on Def compared to Pre-DV (p < 0.0001). Cystocele, vaginal prolapse, and enterocele sizes were significantly larger on Post-DV compared to Pre-DV (p < 0.0001). There were significant differences in grading of all types of prolapse and rectocele between the various acquisitions of MRD (p < 0.0001). Cystocele, AR descent, and rectocele grades were significantly higher on Def compared to Post-DV (p range ≤ 0.0002). Grading of all types of prolapse and rectocele was significantly higher on Def compared to Pre-DV (p < 0.0001). Cystocele, vaginal prolapse, and enterocele grades were all significantly higher on Post-DV compared to Pre-DV (p ≤ 0.0007). CONCLUSION: Defecation images during supine MRD elicit higher prevalence and size of prolapse of all pelvic compartments in comparison to both pre- and post-defecation Valsalva images. Post-defecation Valsalva images show larger size of anterior and middle compartment prolapse than pre-defecation Valsalva images. Functional evaluation of pelvic floor dysfunction with MRI should include image acquisition during defecation. If Valsalva images are acquired, these should be performed after the defecation acquisition and without rectal distention.

Supine magnetic resonance defecography for evaluation of anterior compartment prolapse: Comparison with upright voiding cystourethrogram.

PURPOSE: To compare utility of supine Magnetic Resonance Defecography (MRD) with upright Voiding Cystourethrogram (VCUG) for evaluation of cystocele and urethral hypermobility (UHM). METHODS: This was an IRB-approved, HIPAA-compliant, retrospective study of 51 consecutive patients with symptomatic pelvic organ prolapse (POP) and lower urinary tract symptoms who underwent both upright VCUG and supine MRD. Cystocele height was defined in centimeters with reference to the inferior edge of the pubic bone on VCUG and the pubococcygeal line on MRD. Urethral angle at rest (UAR) and during straining (UAS) was measured in degrees between the urethral axis and a vertical line at the external meatus. Pairedt-test and simple linear regression were applied to compare VCUG and MRD data sets. p < 0.05 was considered significant. RESULTS: The mean cystocele extent was 1.58 cm lower (more inferior to the reference point) (95% CI for the mean difference: 1.21, 1.94;p < 0.0001) on MRD (-2.73 ± 1.99 cm) than on VCUG (-1.16 ± 1.75 cm). Mean UAS on MRD (72.29 ± 26.45) was 31.8 degrees higher compared to that on VCUG (40.45 ± 21.41), (95% CI for mean difference in UAS: 37.57, 26.11; p < 0.0001). Mean UAS-UAR on MRD (74.30 ± 28.50) was 58.6 degrees higher compared to that on VCUG (15.70 ± 11.27) (95% CI for mean difference in UAS-UAR 65.94, 51.26; p < 0.0001). Cystocele size was upgraded in 22 (43.3%) patients on MRD compared to VCUG. Five (9.8%) patients demonstrated UHM on VCUG; 48 (94.1%) patients demonstrated UHM on MRD. The differences between VCUG and MRD scores persisted across the range of VCUG measurements. Cystocele size was significantly larger in POP (+) patients than in POP (-) patients on MRD (p = 0.005) but not on VCUG (p = 0.06). CONCLUSIONS: Supine MRD demonstrates significantly higher prevalence and degree of cystocele and UHM than upright VCUG, and alters the grade of bladder prolapse in a significant portion of the patient population. Cystocele size on MRD correlates with clinical presence of prolapse symptoms.

Synthetic MRI of the Knee: Phantom Validation and Comparison with Conventional MRI.

Purpose To test the hypothesis that synthetic MRI of the knee generates accurate and repeatable quantitative maps and produces morphologic MR images with similar quality and detection rates of structural abnormalities than does conventional MRI. Materials and Methods Data were collected prospectively between January 2017 and April 2018 and were retrospectively analyzed. An International Society for Magnetic Resonance in Medicine-National Institute of Standards and Technology phantom was used to determine the accuracy of T1, T2, and proton density (PD) quantification. Statistical models were applied for correction. Fifty-four participants (24 men, 30 women; mean age, 40 years; range, 18-62 years) underwent synthetic and conventional 3-T MRI twice on the same day. Fifteen of 54 participants (28%) repeated the protocol within 9 days. The intra- and interday agreements of quantitative cartilage measurements were assessed. Contrast-to-noise (CNR) ratios, image quality, and structural abnormalities were assessed on corresponding synthetic and conventional images. Statistical analyses included the Wilcoxon test, χ2 test, and Cohen Kappa. P values less than or equal to .01 were considered to indicate a statistically significant difference. Results Synthetic MRI quantification of T1, T2, and PD values had an overall model-corrected error margin of 0.8%. The synthetic MRI interday repeatability of articular cartilage quantification had native and model-corrected error margins of 3.3% and 3.5%, respectively. The cartilage-to-fluid CNR and menisci-to-fluid CNR was higher on synthetic than conventional MR images (P ≤ .001, respectively). Synthetic MRI improved short-tau inversion recovery fat suppression (P ˂ .01). Intermethod agreements of structural abnormalities were good (kappa, 0.621-0.739). Conclusion Synthetic MRI of the knee is accurate for T1, T2, and proton density quantification, and simultaneously generated morphologic MR images have detection rates of structural abnormalities similar to those of conventional MR images, with similar acquisition time. © RSNA, 2018.

Chemical shift imaging with in-phase and opposed-phase sequences at 3 T: what is the optimal threshold, measurement method, and diagnostic accuracy for characterizing marrow signal abnormalities?

OBJECTIVE: To determine the threshold signal drop on 3-T chemical shift imaging (CSI), with in-phase (IP) and opposed-phase (OP) sequences, for accurately identifying bone marrow replacement with 100% sensitivity, and determine a clinically useful measurement method for deriving such a threshold. MATERIALS AND METHODS: From a convenience series of 157 MRIs, 36 cases with histologically proven marrow-replacing lesions and 22 sites of red marrow (histologically proven (2) or with minimum 6-month stability) with 3-Tesla CSI were included. Two musculoskeletal radiologists performed two measurement methods (first: multiple algorithmic ROIs at the top, middle, and bottom of lesions (M-ROI); second: an ROI was drawn where there appeared to be the least opposed-phase signal reduction qualitatively/visually (Q-ROI)). Lesional and red marrow signal change (%,[(IP-OP)signal/IP signal]*100) was determined. Statistical analyses included Student's t test, Cohen's kappa, and receiver operator characteristic curve generation. RESULTS: By M-ROI, lesion signal change was - 0.508% (confidence interval (CI) = - 5.537:4.521) and 1.348% (CI = - 3.541:6.311) for readers 1 and 2. By Q-ROI, lesion signal change was - 11.03% (CI = - 17.01:- 5.046) and - 5.657% (CI = - 12.36:1.048) for readers 1 and 2. For all M-ROI and Q-ROI measurement strategies, signal change between lesional tissue and red marrow was significantly different (p < 0.0001). QROI produced the best composite sensitivities and specificities with a maximized Youden index of 0.955-1. A threshold signal drop of 25% with Q-ROI produced at least 100%/86% sensitivity/specificity for both readers for identifying marrow replacement. CONCLUSIONS: For 3-T CSI, a single visually targeted measurement using a 25% threshold is accurate for identifying marrow-replacing lesions.

Brief Report: Association of Quantitative and Topographic Assessment of Heberden's Nodes With Knee Osteoarthritis: Data From the Osteoarthritis Initiative.

OBJECTIVE: To determine whether the presence, number, and topography (digit location and symmetry) of Heberden's nodes are associated with the incidence and progression of radiographic osteoarthritis (OA) of the knee. METHODS: We analyzed 8,023 knees (with 8 years of follow-up) from the Osteoarthritis Initiative. Cox regression was performed on Heberden's node presence, total number, location, and symmetry (using 2 symmetry index models) obtained at baseline physical examination as well as self-report of Heberden's node presence for evaluation of association with radiographic knee OA incidence (development of a Kellgren/Lawrence grade of ≥2) and progression (worsening in the medial joint space narrowing score of ≥1). Covariate adjustments relevant to OA outcomes were performed. RESULTS: The presence of Heberden's nodes (in 64% of the subjects) at baseline physical examinations, but not subjective self-report of Heberden's nodes, was associated with radiographic knee OA incidence (hazard ratio [HR] 1.19 and 95% confidence interval [95% CI] 1.001-1.402 [approached statistical significance]). Each additional Heberden's node found on physical examination was associated with knee OA incidence (HR 1.03 [95% CI 1.000-1.054] [approached statistical significance]) and progression (HR 1.04 [95% CI 1.016-1.063]). Knee OA incidence and progression were associated with Heberden's nodes located on the third digit (HR 1.26 [95% CI 1.068-1.487] and 1.18 [95% CI 1.019-1.361], respectively) and first digit (HR 1.186 [95% CI 0.992-1.418] [approached statistical significance] and HR 1.26 [95% CI 1.084-1.453], respectively). Heberden's node symmetry was associated with knee OA incidence (model 1 HR 1.09 [95% CI 0.997-1.185] [approached statistical significance]) and progression (model 2 HR 1.13 [95% CI 1.035-1.234]). CONCLUSION: The number of Heberden's nodes, their locations, and symmetry were associated with knee OA incidence and progression over 8 years.

Metal Artifact Reduction Magnetic Resonance Imaging Around Arthroplasty Implants: The Negative Effect of Long Echo Trains on the Implant-Related Artifact.

OBJECTIVES: Long echo train length (ETL) is an often recommended but unproven technique to decrease metal artifacts on magnetic resonance imaging (MRI) scans. Therefore, we quantitatively and qualitatively assessed the effects of ETL on metal artifact on MRI scans using a cobalt-chromium-containing arthroplasty implant system. MATERIALS AND METHODS: Using a total ankle arthroplasty system implanted into a human cadaver ankle and a clinical 1.5 T MRI system, turbo spin echo (TSE) pulse sequences were acquired with ETL ranging from 3 to 23 and receiver bandwidth (BW) from 100 to 750 Hz/pixel, whereas effective echo time and spatial resolution were controlled. A compressed sensing slice encoding for metal artifact correction TSE prototype pulse sequence was used as reference standard. End points included the total implant-related artifact area and implant-related signal void areas. Two raters evaluated the overall image quality and preference across varying BW and ETL. Two-factor analysis of variance, Friedman test, Kruskal-Wallis test, and Pearson correlation were used. P values of less than 0.05 were considered statistically significant. RESULTS: The total implant-related artifact area ranged from 0.119 for compressed sensing slice encoding for metal artifact correction (BW, 600 Hz/pixel; ETL, 3) to 0.265 for TSE (BW, 100 Hz/pixel; ETL, 23). Longer ETL significantly increases the total implant-related artifact area (P = 0.0004), whereas it decreased with increasing BW (P < 0.0001). Implant-related signal void areas were not significantly affected by larger echo train length, but reduced with higher BW (P < 0.0001). Readers had a significant preference for images with high BW and short ETL (P < 0.0001). CONCLUSIONS: High receiver BW is the most effective parameter for reduction of arthroplasty implant-induced metal artifact on MRI scans, whereas in contradiction to prevalent notions, long echo trains fail to reduce implant-related metal artifacts, but in fact cause degradation of image quality around the implant with resultant larger appearing total metal artifacts.

Transcriptional profile of isoproterenol-induced cardiomyopathy and comparison to exercise-induced cardiac hypertrophy and human cardiac failure.

BACKGROUND: Isoproterenol-induced cardiac hypertrophy in mice has been used in a number of studies to model human cardiac disease. In this study, we compared the transcriptional response of the heart in this model to other animal models of heart failure, as well as to the transcriptional response of human hearts suffering heart failure. RESULTS: We performed microarray analyses on RNA from mice with isoproterenol-induced cardiac hypertrophy and mice with exercise-induced physiological hypertrophy and identified 865 and 2,534 genes that were significantly altered in pathological and physiological cardiac hypertrophy models, respectively. We compared our results to 18 different microarray data sets (318 individual arrays) representing various other animal models and four human cardiac diseases and identified a canonical set of 64 genes that are generally altered in failing hearts. We also produced a pairwise similarity matrix to illustrate relatedness of animal models with human heart disease and identified ischemia as the human condition that most resembles isoproterenol treatment. CONCLUSION: The overall patterns of gene expression are consistent with observed structural and molecular differences between normal and maladaptive cardiac hypertrophy and support a role for the immune system (or immune cell infiltration) in the pathology of stress-induced hypertrophy. Cross-study comparisons such as the results presented here provide targets for further research of cardiac disease that might generally apply to maladaptive cardiac stresses and are also a means of identifying which animal models best recapitulate human disease at the transcriptional level.