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To prospectively compare image quality and apparent diffusion coefficient (ADC) quantification for reduced field-of-view (rFOV)- and multi-shot echo-planar imaging (msEPI)-based diffusion weighted imaging (DWI), using single-shot echo-planar-imaging (ssEPI) DWI as the reference.Under IRB approval and after informed consent, msEPI, rFOV, and ssEPI DWI acquisitions were prospectively added to clinical prostate MRI exams at 3.0 T. Image distortion was quantitatively evaluated by root-mean-squared displacement (dTwenty-five patients were included (15 with proven sites of cancer). Average drFOV and msEPI DWI techniques achieved reduction in image distortion, improvement in image quality, and maintained reproducible ADC quantification compared to the standard ssEPI.

With optimized technique, the water-soluble contrast challenge is effective at triaging patients for operative vs non-operative management of suspected small bowel obstruction. Standardized study structure and interpretation guidelines aid in clinical efficacy and ease of use. Many tips and tricks exist regarding technique and interpretation, and their understanding may assist the interpreting radiologist. In the future, a CT-based water-soluble contrast challenge, utilizing oral contrast given as part of the initial CT examination, might allow for a more streamlined algorithm and provide more rapid results.

There is an unmet need for fully automated image prescription of the liver to enable efficient, reproducible MRI.To develop and evaluate artificial intelligence (AI)-based liver image prescription.Prospective.A total of 570 female/469 male patients (age: 56 ± 17 years) with 72%/8%/20% assigned randomly for training/validation/testing; two female/four male healthy volunteers (age: 31 ± 6 years).1.5 T, 3.0 T; spin echo, gradient echo, bSSFP.A total of 1039 three-plane localizer acquisitions (26,929 slices) from consecutive clinical liver MRI examinations were retrieved retrospectively and annotated by six radiologists. The localizer images and manual annotations were used to train an object-detection convolutional neural network (YOLOv3) to detect multiple object classes (liver, torso, and arms) across localizer image orientations and to output corresponding 2D bounding boxes. Whole-liver image prescription in standard orientations was obtained based on these bounding boxes. 2D detection performance was evaluated on test datasets by calculating intersection over union (IoU) between manual and automated labeling. 3D prescription accuracy was calculated by measuring the boundary mismatch in each dimension and percentage of manual volume covered by AI prescription. The automated prescription was implemented on a 3 T MR system and evaluated prospectively on healthy volunteers.Paired t-tests (threshold = 0.05) were conducted to evaluate significance of performance difference between trained networks.In 208 testing datasets, the proposed method with full network had excellent agreement with manual annotations, with median IoU 0.91 (interquartile range 0.09) across all seven classes. The automated 3D prescription was accurate, with shifts2.3 cm in superior/inferior dimension for 3D axial prescription for 99.5% of test datasets, comparable to radiologists' interreader reproducibility. The full network had significantly superior performance than the tiny network for 3D axial prescription in patients. Automated prescription performed well across single-shot fast spin-echo, gradient-echo, and balanced steady-state free-precession sequences in the prospective study.AI-based automated liver image prescription demonstrated promising performance across the patients, pathologies, and field strengths studied.4.Stage 1.

Percutaneous ultrasound-guided biopsies have become the standard of practice for tissue diagnosis in the abdomen and pelvis for many sites including liver, kidney, abdominal wall, and peripheral nodal stations. Additional targets may appear difficult or impossible to safely biopsy by ultrasound due to interposed bowel loops/vasculature, deep positioning, association with the bowel, or concern for poor visibility; however, by optimizing technique, it is often possible to safely and efficiently use real-time ultrasound guidance for sampling targets that normally would be considered only appropriate for CT guided or surgical/endoscopic biopsy.

Incidental thyroid nodules (ITNs) are common, and variability regarding follow-up and recommendation practices exist. The study purpose was to determine adherence to the American College of Radiology (ACR) ITN criteria and analyze recommendation outcomes.ITNs listed in the impression section on computed tomography, magnetic resonance imaging, and positron emission tomography studies over a 6-month period were included. Report recommendations were compared with ACR white paper criteria for adherence (concordant recommendation) or nonadherence (discordant recommendation). Reader characteristics, further ITN workup, and pathology were recorded. A P value less than 0.05 was used for significance.Three hundred fifty patients (mean age, 64.6 years) were included with a median ITN size of 18-mm. Most nodules (289/350) were reported on computed tomography and were identified for follow-up due to size (235/350). Only 39 of 350 reports (11.1%) did not follow ACR recommendations. Patient age was significantly related to recommendation adherence ( P0.05) as opposed to radiologist practice type (ie, community-based or academic) which was not. Nonadherence most often involved recommending ultrasound follow-up for nonactionable small ITNs. The rate of fine-needle aspiration biopsy from concordant ITNs was significantly higher than discordant ITNs ( P0.05). Six patients, all with concordant recommendations, had malignant final pathology results.Recommendation adherence to the ACR ITN criteria was high, approaching 90%. Nonadherence was mostly due to recommending thyroid ultrasound when not indicated and was correlated with a younger patient age. The rate of fine-needle aspiration biopsy stemming from nonindicated ultrasounds was significantly lower and did not result in the diagnosis of any malignancies.

PURPOSE To compare prostate diffusional kurtosis imaging (DKI) metrics generated using phase-corrected real data with those generated using magnitude data with and without noise compensation (NC). METHODS Diffusion-weighted images were acquired at 3T in 16 prostate cancer patients, measuring 6 b-values (0-1500 s/mm2 ), each acquired with 6 signal averages along 3 diffusion directions, with noise-only images acquired to allow NC. In addition to conventional magnitude averaging, phase-corrected real data were averaged in an attempt to reduce rician noise-bias, with a range of phase-correction low-pass filter (LPF) sizes (8-128 pixels) tested. Each method was also tested using simulations. Pixelwise maps of apparent diffusion (D) and apparent kurtosis (K) were calculated for magnitude data with and without NC and phase-corrected real data. Average values were compared in tumor, normal transition zone (NTZ), and normal peripheral zone (NPZ). RESULTS Simulations indicated LPF size can strongly affect K metrics, where 64-pixel LPFs produced accurate metrics. Relative to metrics estimated from magnitude data without NC, median NC K were lower (P < 0.0001) by 6/11/8% in tumor/NPZ/NTZ, 64-LPF real-data K were lower (P < 0.0001) by 4/10/7%, respectively. CONCLUSION Compared with magnitude data with NC, phase-corrected real data can produce similar K, although the choice of phase-correction LPF should be chosen carefully.

Among 109 iohexol-based water-soluble contrast (WSC) challenges performed for suspected small-bowel obstruction, 105 were technically adequate. Among technically adequate studies, colonic contrast (i.e., successful challenge) was seen on 66 abdominal radiographs obtained 8 hours after WSC challenge and 86 abdominal radiographs obtained 24 hours after WSC challenge. Fourteen patients underwent operative management, and 91 underwent nonoperative management (NOM). Successful challenge had a sensitivity of 91.2%, specificity of 78.5%, PPV of 96.5%, NPV of 57.8%, and odds ratio of 38.0 (95% CI, 8.7-165.2) for NOM. Three of 86 patients with successful challenge underwent operative management.

The purpose of this study was to assess whether a specific liver attenuation threshold for unenhanced CT allows both sensitive opportunistic detection of unsuspected hereditary hemochromatosis and low overall screening test-positive rates.We used a standard ROI placement method on unenhanced CT studies of 3357 consecutive adults (mean age, 57.0 years) with no symptoms of liver disease who underwent colorectal screening. Hepatic attenuation (in HU) was measured to assess test-positive rates at various liver attenuation thresholds. To assess sensitivity, unenhanced hepatic CT attenuation was also measured in 12 patients with hereditary hemochromatosis (mean age, 48.3 years), who were homozygous for the HFE C282Y mutation. All scans were obtained at 120 kV. Serum ferritin levels were recorded for the hereditary hemochromatosis cohort.Mean liver attenuation ± SD among screened adults was 59.4 ± 12.7 HU, compared with 78.7 ± 13.1 HU (range, 59-105 HU) in the hereditary hemochromatosis cohort (p0.001). Screening test-positive rates were 30.6% (n = 1028) at 65 HU, 8.2% (n = 275) at 70 HU, 1.2% (n = 39) at 75 HU, and 0.2% (n = 7) at 80 HU. Corresponding sensitivities for hereditary hemochromatosis at these thresholds were 83.3% (10/12) at 65, 70, and 75 HU; and 50.0% (6/12) at 80 HU. Serum ferritin levels were elevated in all patients with hereditary hemochromatosis (mean, 1678 ng/mL; range, 477-3991 ng/mL).An unenhanced CT liver attenuation threshold of 75 HU was sensitive (83.3%) for hereditary hemochromatosis while maintaining an acceptably low screening test-positive rate (1.2%). An unexplained liver attenuation of 75 HU or more on unenhanced CT should trigger appropriate laboratory investigation for iron overload; early intervention with phlebotomy can limit or prevent organ damage in patients with hemochromatosis.

36 Background: Interest has arisen in the use of prostate specific membrane antigen (PSMA) PET/CT imaging to detect prostate cancer at metastatic sites using different tracers. Here, we examined the ability of 18F-DCFPyL (DCFPyL) PSMA-based PET imaging to detect nodal disease in comparison to conventional imaging in a cohort of men with locally advanced or oligometastatic prostate cancer (PC). Methods: UW17009 is an IRB-approved open-label, single-arm trial that enrolled 26 patients with newly diagnosed advanced PC. Patients received androgen deprivation therapy and docetaxel for 3 months followed by radical prostatectomy (RP) and pelvic lymph node dissection (PLND). Exploratory interventions include PSMA PET/CT and MRI imaging as a method for determining treatment response and heterogeneity in primary PC and metastatic lesions performed before and after chemohormonal therapy. Prior to randomization, patients received DCFPyL PET/CT and PET/MR imaging as well as CTs and Bone Scans. A mean dose of 7.86 mCi DCFPyL was administered. Whole-body PET/CT images were acquired starting at approximately 60 minutes after radiotracer injection followed by dedicated pelvic PET/MR and whole-body PET/MR. PET imaging findings were compared to conventional dedicated CT imaging and were correlated to the results of final pathologic examination of each pelvic nodal dissection. Results: 26 patients underwent conventional and exploratory imaging with subsequent neoadjuvant treatment, RP and PLND. The mean diagnostic PSA was 32.1 ng/dl and 88.5% had Gleason 9 PCa. Using conventional imaging, pelvic nodal disease was identified in 6/26 patients. Pelvic lymph node uptake was identified in 12/26 patients using DCFPyL-based PSMA PET. Initial correlation of the pathologic specimens with pretreatment PSMA PET imaging revealed pelvic nodal metastatic PC in 10/12(83%) patients. On a per-lymph node packet basis (6 per patient), there were 156 evaluable regions, including 65 from patients with positive nodes. PSMA detected 14 packets that were positive for PC and 102 packets that were negative on imaging and final pathology. PC was missed in 5 packets. The mean tumor size in the missed nodes was 2.3 mm(range 1-4 mm). Calculated sensitivity was 73.7%(95% CI [48.8, 90.8]), 85.7 % specificity(95% CI[78.1, 91.4]), and 95.3 % negative predictive value(95% CI[90.5, 97.7]). Conclusions: In comparison to conventional imaging, in this cohort, DCFPyL PSMA-based PET imaging identified nodal positive disease at twice the rate and when evaluating on a per-packet basis, there was high negative predictive value. Ongoing analysis of post-chemohormonal therapy PET imaging may provide more information regarding tumor response in this cohort.

To investigate the repeatability of diffusion-weighted imaging parameter including ADC-derived histogram values in prostate cancer.10 patients with prostate cancer were prospectively recruited to a retest cohort. 3 T diffusion-weighted MRI of the prostate was acquired consecutively with patient getting off the scanner between studies. Prostatectomy-histopathology defined tumour regions-of-interest were outlined on ADC maps and diffusion-weighted metrics including histograms were calculated. The coefficient of reproducibility (CoR) and Bland-Altman plots were used to assess repeatability.1010

Objective To evaluate diffusion kurtosis imaging (DKI) and magnetisation transfer imaging (MTI) compared to standard MRI for prostate cancer assessment in a re-biopsy population. Methods Thirty-patients were imaged at 3 T including DKI (Kapp and Dapp) with b-values 150/450/800/1150/1500 s/mm2 and MTI performed with and without MT saturation. Patients underwent transperineal biopsy based on prospectively defined MRI targets. Receiver-operating characteristic (ROC) analyses assessed the parameters and Wilcoxon-signed ranked test assessed relationships between metrics. Results Twenty patients had ≥ 1 core positive for cancer in a total of 26 MRI targets (Gleason 3+3 in 8, 3+4 in 12, ≥ 4+3 in 6): 13 peripheral (PZ) and 13 transition zone (TZ). The apparent diffusion coefficient (ADC) and Dapp were significantly lower and the Kapp and MT ratio (MTR) significantly higher in tumour versus benign tissue (all p ≤ 0.005); ROC values 0.767-1.000. Normal TZ had: lower ADC and Dapp and higher Kapp and MTR compared to normal PZ. MTR showed a moderate correlation to Kapp (r = 0.570) and Dapp (r = -0.537) in normal tissue but a poor correlation in tumours. No parameter separated low-grade (Gleason 3+3) from high-grade (≥ 3+4) disease for either PZ (p = 0.414-0.825) or TZ (p = 0.148-0.825). Conclusion ADC, Dapp, Kapp and MTR all distinguished benign tissue from tumour, but none reliably differentiated low- from high-grade disease. Key Points • MTR was significantly higher in PZ and TZ tumours versus normal tissue • K app was significantly lower and D app higher for PZ and TZ tumours • There was no incremental value for DKI/MTI over mono-exponential ADC parameters • No parameter could consistently differentiate low-grade (Gleason 3+3) from high-grade (≥ 3+4) disease • Divergent MTR/DKI values in TZ tumours suggests they offer different functional information Electronic supplementary material The online version of this article (10.1007/s00330-017-5169-1) contains supplementary material, which is available to authorized users.

OBJECTIVE: The purpose of this study was to investigate the ability of the apparent diffusion coefficient (ADC) ratio of tumor to normal prostate tissue to overcome inherent variability based on choice of b values, with whole-mount histopathologic analysis as the reference standard for tumor identification. MATERIALS AND METHODS: Thirty-nine patients with prostate cancer underwent 3-T MRI, including DWI with b values of 0, 150, 750, and 1000 s/mm(2). ADC maps were derived from four b value combinations. Histologically derived ROIs were defined for prostate tumor and benign prostate tissue to generate a ratio. The concordance correlation coefficient was used to evaluate agreement and reproducibility at different b values. Bland-Altman plots were used to evaluate the pattern of relative measurement difference between b value combinations. The relationship between ADC values and Gleason score was tested by Spearman rank correlation. RESULTS: ADC values varied depending on the b value combination selected. The concordance correlation coefficient was higher for ADC ratios (0.883; 95% CI, 0.816-0.927) compared with absolute ADC values for normal tissue (0.873; 95% CI, 0.799-0.921) and tumor (0.792; 95% CI, 0.688-0.864). The ADC ratio concordance correlation coefficient for transition zone tumors was considerably higher than that for the peripheral zone in all cases. Bland-Altman analysis showed higher variation for ADC maps incorporating a b value of zero for both ratio and absolute values. There was a stronger inverse relationship to Gleason score for ADC ratios (rho, -0.354 to -0.456) compared with absolute ADC values (rho, -0.117 to -0.379). CONCLUSION: The use of a simple ratio of prostate tumor ADC to normal tissue ADC improved the concordance between different b value combinations and could provide a more robust means of assessing restricted diffusion in the prostate.

Diffusion-weighted magnetic resonance imaging (DW-MRI) is considered part of the standard imaging protocol for the evaluation of patients with prostate cancer. It has been proven valuable as a functional tool for qualitative and quantitative analysis of prostate cancer beyond anatomical MRI sequences such as T2-weighted imaging. This review discusses ongoing controversies in DW-MRI acquisition, including the optimal number of b-values to be used for prostate DWI, and summarizes the current literature on the use of advanced DW-MRI techniques. These include intravoxel incoherent motion imaging, which better accounts for the non-mono-exponential behavior of the apparent diffusion coefficient as a function of b-value and the influence of perfusion at low b-values. Another technique is diffusion kurtosis imaging (DKI). Metrics from DKI reflect excess kurtosis of tissues, representing its deviation from Gaussian diffusion behavior. Preliminary results suggest that DKI findings may have more value than findings from conventional DW-MRI for the assessment of prostate cancer.