Automated analysis of the total choline resonance peak in breast proton magnetic resonance spectroscopy.

The aim of the current study was to compare the performance of fully automated software with human expert interpretation of single-voxel proton magnetic resonance spectroscopy (1H-MRS) spectra in the assessment of breast lesions. Breast magnetic resonance imaging (MRI) (including contrast-enhanced T1-weighted, T2-weighted, and diffusion-weighted imaging) and 1H-MRS images of 74 consecutive patients were acquired on a 3-T positron emission tomography-MRI scanner then automatically imported into and analyzed by SpecTec-ULR 1.1 software (LifeTec Solutions GmbH). All ensuing 117 spectra were additionally independently analyzed and interpreted by two blinded radiologists. Histopathology of at least 24 months of imaging follow-up served as the reference standard. Nonparametric Spearman's correlation coefficients for all measured parameters (signal-to-noise ratio [SNR] and integral of total choline [tCho]), Passing and Bablok regression, and receiver operating characteristic analysis, were calculated to assess test diagnostic performance, as well as to compare automated with manual reading. Based on 117 spectra of 74 patients, the area under the curve for tCho SNR and integrals ranged from 0.768 to 0.814 and from 0.721 to 0.784 to distinguish benign from malignant tissue, respectively. Neither method displayed significant differences between measurements (automated vs. human expert readers, p > 0.05), in line with the results from the univariate Spearman's rank correlation coefficients, as well as the Passing and Bablok regression analysis. It was concluded that this pilot study demonstrates that 1H-MRS data from breast MRI can be automatically exported and interpreted by SpecTec-ULR 1.1 software. The diagnostic performance of this software was not inferior to human expert readers.

Radiation dose reduction capabilities of a new C-arm system with optimized hard- and software.

PURPOSE: To assess the radiation dose reduction capabilities and the image quality of a new C-arm system in comparison to a standard C-arm system. METHOD: Prospective, randomized, IRB approved two-arm trial design. 49 consecutive patients with primary or secondary liver cancer were treated with transarterial chemoembolization (TACE) on two different angiography units. 28 patients were treated on a conventional angiography unit B, 21 patients on unit A which provides improved hardware and optimized image processing algorithms. Dose area product (DAP) and fluoroscopy time were recorded. DSA image quality of all procedures was assessed on a four-rank-scale by two independent and blinded readers. RESULTS: Both cohorts showed no significant differences with regard to patient characteristics, tumor burden and fluoroscopy time. The new system resulted in a statistically significant reduction of cumulative DAP of 72% compared to the old platform (median 76 vs. 269 Gy*cm2). Individually, Fluoro-DAP and DSA-DAP decreased by 48% and 77% (p = 0.012 and p < 0.01), respectively. No statistically significant differences in DSA image quality were found between the two imaging platforms. CONCLUSIONS: The new C-arm system significantly reduced radiation exposure for TACE procedures without increased radiation time or negative impact on DSA image quality. The combination of optimized hardware and software yields the highest radiation dose reduction and is of utmost importance for patients and interventionalists.

Application of Baseline Clinical and Morphological Parameters for Prediction of Late Stent Graft Related Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysm.

OBJECTIVES: To evaluate the influence of baseline clinical and morphological parameters on the occurrence of a late stent graft related endoleak (srEL; types 1 and 3) after endovascular aneurysm repair (EVAR). METHODS: This is a retrospective case control study of patients who were routinely followed up after EVAR of abdominal aortic aneurysms. Pre-interventional, pre-discharge, and last available multislice computed tomography angiogram (MSCTA) of 279 patients were analysed. Stent graft related endoleaks detected by follow up MSCTA at least six months after EVAR were specified as late srEL. Baseline demographic characteristics and morphological variables were derived from the pre-interventional and pre-discharge MSCTA. Univariable and multivariable analysis with a Cox proportional hazards model were used to determine baseline factors associated with the occurrence of a late srEL. RESULTS: Twenty-four (8.6%) of 279 patients suffered a late srEL, during a mean MSCTA follow up of 30.9 ± 25.8 (23.5, IQR 10.6-42.8) months. In the univariable analysis, age (hazard ratio [HR] 1.09; p = .001), female sex (HR 3.25; p = .014), right iliac sealing diameter (HR 10.04; p = .03), left iliac sealing diameter (HR 8.65; p = .001), infrarenal aortic neck angulation (HR 1.02; p = .011), and suprarenal fixation level (HR 3.47; p = .014) were significantly associated with an increased incidence of late srEL. Age (HR 1.08; p = .012), female sex (HR 2.72; p = .049), and left iliac sealing diameter (HR 4.48; p = .033) proved to be risk factors significantly associated with a higher incidence of late srEL in multivariable analysis. CONCLUSIONS: Older patients, those with female gender, and those with larger left iliac sealing diameters seem to experience higher rates of late srEL. Independent confirmation of these must be addressed in larger studies.

Paclitaxel-Eluting Balloon Versus Standard Balloon Angioplasty in In-Stent Restenosis of the Superficial Femoral and Proximal Popliteal Artery: 1-Year Results of the PACUBA Trial.

OBJECTIVES: The hypothesis that paclitaxel-eluting balloon angioplasty provides higher 1-year patency rates in femoropopliteal artery in-stent restenosis compared with standard percutaneous transluminal angioplasty (PTA) was tested. BACKGROUND: Several trials have demonstrated that paclitaxel-eluting balloon angioplasty reduces late luminal loss in comparison with PTA. METHOD: In a prospective, randomized, single-blind, dual-center study, 74 patients with symptomatic peripheral artery disease due to in-stent restenosis were treated with either paclitaxel-based drug-eluting balloon (DEB) angioplasty (n = 35) or standard PTA (n = 39). Clinical outcomes and patency rates were assessed at 1, 6, and 12 months. RESULTS: The mean lesion length was 17.3 ± 11.3 cm in the DEB group and 18.4 ± 8.8 cm in the PTA group. A single major complication (bleeding) was observed once (1.4%). The mean ankle-brachial index before endovascular treatment was 0.65 ± 0.16 in both groups and 0.79 ± 0.2 versus 0.84 ± 0.3 (p = 0.70, Student t test) in the DEB versus PTA group at 12 months. The 12-month primary patency rates were 40.7% (95% confidence interval [CI]: 0.26 to 0.64) versus 13.4% (95% CI: 0.05 to 0.36) (log-rank p = 0.02) in the DEB versus PTA group. The odds ratio for PTA over DEB angioplasty for experiencing an event was estimated at 2.8 (95% CI: 1.2 to 6.6). Freedom from clinically driven target lesion revascularization was 49.0% (95% CI: 0.32 to 0.75) versus 22.1% (95% CI: 0.10 to 0.48) (log-rank p = 0.11) in the DEB versus PTA group. Clinical improvement by ≥1 Rutherford-Becker category was 68.8% versus 54.5% (p = 0.87) in the DEB versus PTA group at 12 months. CONCLUSIONS: When treating peripheral artery disease in patients with in-stent restenosis in the femoropopliteal artery, paclitaxel-eluting balloon angioplasty provides significantly higher patency rates than standard PTA. (Paclitaxel Balloon Versus Standard Balloon in In-Stent Restenoses of the Superficial Femoral Artery [PACUBA I Trial] [PACUBA 1]; NCT01247402).

Inter-observer variation and diagnostic efficacy of apparent diffusion coefficient (ADC) measurements obtained by diffusion-weighted imaging (DWI) in small renal masses.

BACKGROUND: Diffusion-weighted imaging (DWI) is increasingly used to diagnose renal lesion subtypes. Especially in small renal masses, identification of less aggressive tumor types is of clinical interest, as active surveillance strategies can be applied. PURPOSE: To evaluate the inter-observer variation and diagnostic efficacy of apparent diffusion coefficient (ADC) measurements obtained by DWI in small renal masses ≤4 cm (SRM). MATERIAL AND METHODS: This retrospective IRB-approved study included 39 patients (46 SRM: 12 benign, 34 malignant). All underwent a 3 T DWI of SRM prior to surgery. Two radiologists independently analyzed all imaging data by three measurements. Limits of agreement, intraclass correlation coefficients (ICC), group comparisons by t-tests, and ROC analysis were performed. RESULTS: Reliability of ADC measurements was very high with an ICC of >0.9 for both observers. Inter-rater reliability was high with an ICC of 0.82. Limits of agreement for average ADC values between both observers were -23.5% to 38.3% with a mean difference of 7.5% between both observers. No significant differences were found between benign and malignant lesions (P value Observer 1: 0.362, Observer 2: 0.622). Papillary carcinoma showed lower ADC values compared to non-papillary carcinoma (P value Observer 1: 0.008, Observer 2: 0.012). Consequently, ROC analysis revealed a significant (P < 0.001, respectively) area under the ROC curve of 0.853 (Observer 1) and 0.837 (Observer 2) without significant differences between both readers (P = 0.772). CONCLUSION: ADC measurements of SRM at 3 T show a high reproducibility and differentiate papillary from non-papillary carcinoma subtypes. However, measurement variability may limit the application of fixed ADC thresholds for lesion diagnosis.

Diagnosis of renal tumors by in vivo proton magnetic resonance spectroscopy.

PURPOSE: To evaluate the diagnostic potential of choline measurements by in vivo magnetic resonance spectroscopy (MR spectroscopy) for diagnosis of renal masses. METHODS: Twenty-eight patients with 29 renal lesions underwent prospectively preoperative 3 T MR spectroscopy of renal masses before diagnostic tissue confirmation. A respiratory-triggered single-voxel MR spectroscopy was performed in these masses using the point-resolved spectroscopy (TR, 2,000 ms, TE, 135 ms) sequence. The spectra were analyzed for choline resonances at 3.23 ppm, which were normalized by the noise outside the diagnostic range of the spectra. Image and spectra analyses were conducted blinded to all patient-related data. Histological results of the surgical resection or image-guided biopsy specimen were defined as the standard of reference. Appropriate statistical tests were used. RESULTS: Seventeen lesions were histopathologically malignant, and 12 lesions were benign. Mean choline SNR in malignant lesions was 2.9 and 1.33 in benign lesions (P = 0.019). ROC analysis revealed an area under the curve of 0.721 and SE 0.0763 with a P value of 0.0038. A Cho SNR ≥2 as cutoff for malignancy resulted in a sensitivity and specificity of 52.9 % (95 % CI 27.8-77.0 %) and 91.7 % (61.5-99.8 %), respectively. Although not significant, choline was observed more regularly in G3 (4 out of 5) compared with G2 (5 out of 12) RCC (P > 0.05). CONCLUSIONS: We could demonstrate the potential role of in vivo MR spectroscopy as a tool for differentiating benign from malignant masses with a high positive predictive value of 90 %. Furthermore, choline may be a biomarker of RCC aggressiveness.

(18)F-DOPA PET/CT and MRI: description of 12 histologically-verified pheochromocytomas.

AIM: To describe the (18)F-fluorodihydro-xyphenylalanine ((18)F-DOPA), positron emission tomography (PET) and magnetic resonance imaging (MRI) appearance of pheochromocytomas, with a focus on the presence or absence of typical MRI features. MATERIALS AND METHODS: Eleven patients with histologically-verified pheochromocytoma [sporadic (n=9), multiple endocrine neoplasia (MEN) 2A syndrome (n=2)] were enrolled retrospectively. All patients underwent an MRI examination of the upper abdomen. Nine out of 11 patients underwent (18)F-DOPA PET/CT, and the remaining two patients underwent independent PET and computed tomography (CT) examinations. (18)F-DOPA-PET/CT examinations were considered positive when an increased tracer accumulation in the adrenal region, as shown on CT images, was observed. When an adrenal mass was detected on MRI, the T1 and T2 signal intensity and contrast enhancement pattern were recorded. Based on MR characteristics, the lesions were divided into typical and atypical. RESULTS: Ten out of 11 patients had one lesion, while one patient had two lesions. All pheochromocytomas were detected by both PET/CT and MRI. On (18)F-DOPA scans, all lesions showed an increased tracer accumulation, with a mean maximum standardized uptake value (SUVmax) of 13.7±5.75. Eight out of 12 pheochromocytomas exhibited typical MRI features, with intermediate signal intensity on T1-weighted images in-phase, absence of signal drop on T1-weighted images out-of-phase, high signal intensity on T2-weighted images, and clear contrast enhancement in the arterial phase. The remaining four lesions exhibited atypical MRI features, namely absence of one of the listed criteria. CONCLUSION: In the assessment of pheochromocytoma, the combination of (18)F-DOPA PET with MRI is superior to MRI-alone. (18)F-DOPA PET/MRI may yield a higher diagnostic confidence for the detection of pheochromocytoma than (18)F-DOPA PET/CT.