Feasibility of using half-dose Gd-BOPTA for delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) at the knee, compared with standard-dose Gd-DTPA.

BACKGROUND: We sought to replace full-dose Gd-DTPA with safer and lower-dose contrast agents for delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). Gd-BOPTA has a lower intrinsic nephrogenic systemic fibrosis risk and a 2-fold higher relaxivity at 3T; thus, the contrast agent dose may be halved, further reducing contrast agent-dependent risks. PURPOSE: To compare the feasibility of using half-dose, high-relaxivity Gd-BOPTA vs. standard-dose Gd-DTPA for dGEMRIC. STUDY TYPE: Prospective observational study. SUBJECTS: Eleven healthy volunteers (five women, mean age 25.7 years) and 10 patients with knee pain (three women, mean age 36.7 years; nine with chondromalacia). FIELD STRENGTH/SEQUENCES: 3D T1 -weighted volumetric breath-hold examination (VIBE) sequence at 3T. ASSESSMENT: Knee dGEMRIC was performed twice, first using 0.1 mmol/kg Gd-BOPTA and 4 weeks later using 0.2 mmol/kg Gd-DTPA. Contrast penetration was studied using pre- and 60-120-min postcontrast imaging in volunteers and pre- and 90-min postcontrast imaging in patients. Femoral cartilage lesions were assessed using modified whole-organ MRI scores. Healthy cartilage and partial-thickness lesions were compared using region-of-interest analyses by independent readers. STATISTICAL TESTS: Linear mixed-effect-models, area under receiver-operating-characteristic curve (AUC) analysis, intraclass correlation (ICC). RESULTS: In healthy volunteers, Gd-BOPTA and Gd-DTPA T1 -values did not differ significantly at any timepoint (P = 0.164-0.995). In patients, Gd-BOPTA T1 -values (743.33 ± 72.015 msec) were higher than Gd-DTPA T1 -values (681.24 ± 67.635 msec, P = 0.030). Gd-BOPTA and Gd-DTPA detected chondromalacia areas equally well, with significantly lower T1 -values than in healthy cartilage (P < 0.001) and nonsignificantly different AUCs (0.92 and 0.96, P = 0.27). The absolute decrease in T1 -values between healthy and pathological cartilage was similar (Gd-BOPTA: 149.59 msec; Gd-DTPA: 149.44 msec, P = 0.99). ICCs were 0.83-0.98 for Gd-BOPTA and 0.80-0.98 for Gd-DTPA. DATA CONCLUSION: Gd-BOPTA might be used at half the Gd-DTPA dose in dGEMRIC, with similar contrast penetration and T1 -values in healthy cartilage and noninferior detection of cartilage damage. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2020;51:144-154.

A Radiogenomic Approach for Decoding Molecular Mechanisms Underlying Tumor Progression in Prostate Cancer.

Prostate cancer (PCa) is a genetically heterogeneous cancer entity that causes challenges in pre-treatment clinical evaluation, such as the correct identification of the tumor stage. Conventional clinical tests based on digital rectal examination, Prostate-Specific Antigen (PSA) levels, and Gleason score still lack accuracy for stage prediction. We hypothesize that unraveling the molecular mechanisms underlying PCa staging via integrative analysis of multi-OMICs data could significantly improve the prediction accuracy for PCa pathological stages. We present a radiogenomic approach comprising clinical, imaging, and two genomic (gene and miRNA expression) datasets for 298 PCa patients. Comprehensive analysis of gene and miRNA expression profiles for two frequent PCa stages (T2c and T3b) unraveled the molecular characteristics for each stage and the corresponding gene regulatory interaction network that may drive tumor upstaging from T2c to T3b. Furthermore, four biomarkers (ANPEP, mir-217, mir-592, mir-6715b) were found to distinguish between the two PCa stages and were highly correlated (average r = ± 0.75) with corresponding aggressiveness-related imaging features in both tumor stages. When combined with related clinical features, these biomarkers markedly improved the prediction accuracy for the pathological stage. Our prediction model exhibits high potential to yield clinically relevant results for characterizing PCa aggressiveness.

Feasibility of gadoteric acid for delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) at the wrist and knee and comparison with Gd-DTPA.

PURPOSE: To assess the feasibility of gadoteric acid for delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) and to compare the dGEMRIC values obtained using gadoteric acid with those obtained by an equimolar dose of Gd-DTPA. MATERIALS AND METHODS: At 3T, dGEMRIC of the wrist was performed twice using a T1 -weighted 3D-volumetric interpolated breath-hold examination sequence in 16 healthy volunteers (10 women; mean age 26.0 years) using gadoteric acid first and Gd-DTPA 3 weeks later. In addition, 24 patients with knee pain were examined using gadoteric acid (n = 12; seven women; mean age 45.8 years) or Gd-DTPA (n = 12; four women; mean age 47.1 years). T1 values, the relative decrease in T1 , and the delta R1 were compared using t-tests. Interobserver agreement was assessed using the intraclass correlation (ICC) between two independent readers. RESULTS: At the wrist, there was no significant difference in delta R1 values (0.34 ± 0.10/s, 95% confidence interval [0.30;0.38]/s for gadoteric acid and 0.32 ± 0.09 [0.29;0.35]/s for Gd-DTPA, P = 0.24) or the relative decrease in T1 (0.25 ± 0.06 [0.29;0.35] msec for gadoteric acid and 0.24 ± 0.05 [0.22;0.27] msec for Gd-DTPA, P = 0.35). High observer agreement was found at precontrast (ICC = 0.87, P < 0.001) and postcontrast (ICC = 0.89, P < 0.001). Similarly, at the knee, there was no significant difference in delta R1 (0.39 ± 0.18 [0.32;0.47]/s for gadoteric acid and 0.41 ± 0.09 [0.38;0.45]/s for Gd-DTPA, P = 0.59) or the relative decrease in T1 (0.30 ± 0.10 [0.26;0.34] msec for gadoteric acid and 0.33 ± 0.05 [0.30;0.35] msec for Gd-DTPA, P = 0.28). High ICCs of 0.96 (P < 0.01) were noted both at precontrast and postcontrast. CONCLUSION: dGEMRIC using gadoteric acid is feasible and yields comparable values when compared with Gd-DTPA. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1433-1440.

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and T2 mapping at 3T MRI of the wrist: Feasibility and clinical application.

PURPOSE: To assess the feasibility of delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and T2 mapping for biochemical imaging of the wrist at 3T. MATERIALS AND METHODS: Seventeen patients with wrist pain (mean age, 41.4 ± 13.1 years) including a subgroup with chondromalacia (n = 11) and 15 healthy volunteers (26.0 ± 2.2 years) underwent dGEMRIC and T2 mapping at 3T. For dGEMRIC, the optimum time window after contrast-injection (gadopentetate dimeglumine) was defined as the plateau of the T1 curve of repeated measurements 15-90 minutes postinjection and assessed in all volunteers. Reference values of healthy-appearing cartilage from all individuals and values in areas of chondromalacia were assessed using region-of-interest analyses. Receiver-operating-characteristic analyses were applied to assess discriminatory ability between damaged and normal cartilage. RESULTS: The optimum time window was 45-90 minutes, and the 60-minute timepoint was subsequently used. In chondromalacia, dGEMRIC values were lower (551 ± 84 msec, P < 0.001), and T2 values higher (63.9 ± 17.7, P = 0.001) compared to healthy-appearing cartilage of the same patient. Areas under the curve did not significantly differ between dGEMRIC (0.91) and T2 mapping (0.99; P = 0.17). In healthy-appearing cartilage of volunteers and patients, mean dGEMRIC values were 731.3 ± 47.1 msec and 674.6 ± 72.1 msec (P = 0.01), and mean T2 values were 36.5 ± 5 msec and 41.1 ± 3.2 msec (P = 0.009), respectively. CONCLUSION: At 3T, dGEMRIC and T2 mapping are feasible for biochemical cartilage imaging of the wrist. Both techniques allow separation and biochemical assessment of thin opposing cartilage surfaces and can distinguish between healthy and damaged cartilage. LEVEL OF EVIDENCE: 3 J. Magn. Reson. Imaging 2017;45:381-389.