Value of bowel preparation techniques for prostate MRI: a preliminary study.

BACKGROUND: Bowel preparation before multiparametric MRI (mpMRI) of the prostate is performed widely, despite contradictory or no evidence for efficacy. PURPOSE: To investigate the value of hyoscine N-butylbromide (HBB), microenema (ME) and 'dietary restrictions' (DR) for artifact reduction and image quality (IQ) in mpMRI of the prostate. STUDY TYPE: Retrospective. POPULATION: Between 10/2018 and 02/2020 treatment-naïve men (median age, 64.9; range 39.8-87.3) who underwent mpMRI of the prostate were included. The total patient sample comprised of n = 180 patients, who received either HBB, ME, were instructed to adhere to DR, or received a combination of those measures prior to the MR scan. FIELD STRENGTH/SEQUENCE: T2-weighted imaging (T2w), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced MRI (DCE-MRI) scanned on two 3T systems. ASSESSMENT: A radiologist specialized in urogenital imaging (R1) and a senior radiology resident (R2) visually assessed IQ parameters on transversal T2w, DWI and ADC maps on a 5-point Likert-like scale. STATISTICAL TESTS: Group comparison between IQ parameters was performed on reader level using Kruskal-Wallis and Mann-Whitney U tests. Binary univariate logistic regression analysis was used to assess independent predictors of IQ. Interrater agreement was assessed using Intraclass Correlation Coefficient (ICC). RESULTS: 'DWI geometric distortion' was significantly more pronounced in the HBB+/ME-/DR- (R1, 3.6 and R2, 4.0) as compared to the HBB-/ME+/DR- (R1, 4.2 and R2, 4.6) and HBB+/ME+/DR- (R1, 4.3 and R2, 4.7) cohort, respectively. Parameters 'DWI IQ' and 'Whole MRI IQ' were rated similarly by both readers. ME was a significant independent predictor of 'good IQ' for the whole MRI for R1 [b = 1.09, OR 2.98 (95% CI 1.29, 6.87)] and R2 [b = 1.01, OR 2.73 (95% CI 1.24, 6.04)], respectively. DATA CONCLUSION: ME seems to significantly improve image quality of DWI and the whole mpMRI image set of the prostate. HBB and DR did not have any benefit.

Impact of different phased-array coils on the quality of prostate magnetic resonance images.

PURPOSE: To evaluate the influence of body phased-array (BPA) receive coil setups on signal-to-noise ratio (SNR) and image quality (IQ) in prostate MRI. METHODS: This prospective study evaluated axial T2-weighted images (T2W-TSE) and DWI of the prostate in ten healthy volunteers with 18-channel (18CH), 30-channel and 60-channel (60CH) BPA receive coil setups. SNR and ADC values were assessed in the peripheral and transition zones (TZ). Two radiologists rated IQ features. Differences in qualitative and quantitative image features between BPA receive coil setups were compared. After correction for multiple comparisons, p-values <0.004 for quantitative and p-values <0.017 for qualitative image analysis were considered statistically significant. RESULTS: Significantly higher SNR was found in T2W-TSE images in the TZ using 60CH BPA compared to 18CH BPA coil setups (15.20 ± 4.22 vs. 7.68 ± 2.37; p = 0.001). There were no significant differences between all other quantitative (T2W-TSE, p = 0.007-0.308; DWI, p = 0.024-0.574) and qualitative image features (T2W-TSE, p = 0.083-1.0; DWI, p = 0.046-1.0). CONCLUSION: 60CH BPA receive coil setup showed marginal SNR improvement in T2W-TSE images. Good IQ could be achieved with 18CH BPA coil setups.

Value of an online PI-RADS v2.1 score calculator for assessment of prostate MRI.

PURPOSE: To evaluate the value of a browser-based PI-RADS Score Calculator (PCalc) compared to MRI reporting using the official PI-RADS v2.1 document (PDoc) for non-specialized radiologists in terms of reporting efficiency, interrater agreement and diagnostic accuracy for detection of clinically significant prostate cancer (PCa). METHODS: Between 09/2013 and 04/2015, 100 patients (median age, 64.8; range 47.5-78.2) who underwent prostate-MRI at a 3 T scanner and who received transperineal prostate mapping biopsy within <6 months were included in this retrospective study. Two non-specialized radiology residents (R1, R2) attributed a PI-RADS version 2.1 score for the most suspect (i. e. index) lesion (i) using the original PI-RADS v2.1 document only and after a 6-week interval (ii) using a browser-based PCalc. Reading time was measured. Reading time differences were assessed using Wilcoxon signed rank test. Intraclass-correlation Coefficient (ICC) was used to assess interrater agreement (IRA). Parameters of diagnostic accuracy and ROC curves were used for assessment of lesion-based diagnostic accuracy. RESULTS: Cumulative reading time was 32:55 (mm:ss) faster when using the PCalc, the difference being statistically significant for both readers (p < 0.05). The difference in IRA between the image sets (ICC 0.55 [0.40, 0.68]) and 0.75 [0.65, 0.82] for the image set with PDoc and PCalc, respectively) was not statistically significant. There was no statistically significant difference in lesion-based diagnostic accuracy (AUC 0.83 [0.74, 0.92] and 0.82 [95 %CI: 0.74, 0.91]) for images assessed with PDoc as compared to PCalc (AUC 0.82 [0.74, 0.91] and 0.74 [95 %CI: 0.64, 0.83]) for R1 and R2, respectively. CONCLUSION: Non-specialized radiologists may increase reading speed in prostate MRI with the help of a browser-based PI-RADS Score Calculator compared to reporting using the official PI-RADS v2.1 document without impairing interreader agreement or lesion-based diagnostic accuracy for detection of clinically significant PCa.

Magnetic resonance imaging of the prostate after focal therapy with high-intensity focused ultrasound.

For clinically significant, locally confined prostate cancer, whole-gland radical prostatectomy and radiotherapy are established effective treatment strategies that, however, come at a cost of significant morbidity related to urinary and sexual side effects. The concept of risk stratification paired with a better understanding of prognostic factors has led to the development of alternative management options including active surveillance and focal therapy for appropriately selected patients with localized disease. High-intensity focused ultrasound (HIFU) is one such minimally invasive, image-guided treatment option for prostate cancer. Due to the relative novelty of HIFU and the increased use of magnetic resonance imaging in prostate cancer, many radiologists are not yet familiar with imaging findings related to HIFU, their temporal evolution as well as imaging appearance of recurrent disease after this type of focal therapy. HIFU induces sharply demarcated, localized coagulative necrosis of a tumor through thermal energy delivered via an endorectal or transurethral ultrasound transducer. In this pictorial review, we aim at providing relevant background information that will guide the reader through the general principles of HIFU in the prostate, as well as demonstrate the imaging appearance of expected post-HIFU changes versus recurrent tumor.

Does quantitative assessment of arterial phase hyperenhancement and washout improve LI-RADS v2018-based classification of liver lesions?

OBJECTIVES: To compare interreader agreement and diagnostic accuracy of LI-RADS v2018 categorization using quantitative versus qualitative MRI assessment of arterial phase hyperenhancement (APHE) and washout (WO) of focal liver lesions. METHODS: Sixty patients (19 female; mean age, 56 years) at risk for HCC with 71 liver lesions (28 HCCs, 43 benign) who underwent contrast-enhanced MRI were included in this retrospective study. Four blinded radiologists independently assigned a qualitative LI-RADS score per lesion. Two other radiologists placed ROIs within the lesion, adjacent liver parenchyma, and paraspinal musculature on pre- and post-contrast MR images. The percentage of arterial enhancement and the liver-to-lesion contrast ratio were calculated for quantification of APHE and WO. Using these quantitative parameters, a quantitative LI-RADS score was assigned. Interreader agreement and AUCs were calculated. RESULTS: Interreader agreement was similar for qualitative and quantitative LI-RADS (κ = 0.38 vs. 0.40-0.47) with a tendency towards improved agreement for quantitatively assessed APHE (κ = 0.65 vs. 0.81) and WO (κ = 0.53 vs. 0.78). Qualitative LI-RADS showed an AUC of 0.86, 0.94, 0.94, and 0.91 for readers 1, 2, 3, and 4, respectively. The quantitative LI-RADS score where APHE/WO/or both were replaced showed an AUC of 0.89/0.84/0.89, 0.95/0.92/0.92, 0.93/0.91/0.89, and 0.91/0.86/0.88 for readers 1, 2, 3, and 4, respectively. Sensitivity of LR-4/5 slightly increased, while specificity slightly decreased using quantitative APHE. CONCLUSION: Qualitative and quantitative LI-RADS showed similar performance. Quantitatively assessed APHE showed the potential to increase interreader agreement and sensitivity of HCC diagnosis, whereas quantitatively assessed WO had the opposite effect and needs to be redefined. KEY POINTS: • Quantitative assessment of arterial phase hyperenhancement shows the potential to increase interreader agreement and sensitivity to diagnose hepatocellular carcinoma. • Adding quantitative measurements of major LI-RADS features does not improve accuracy over qualitative assessment alone according to the LI-RADS v2018 algorithm.

Vertical Off-Centering in Reduced Dose Chest-CT: Impact on Effective Dose and Image Noise Values.

OBJECTIVES: To assess the effect of vertical off-centering in tube current modulation (TCM) on effective-dose and image-noise in reduced-dose (RD) chest-CT. METHODS: One-hundred consecutive patients (36 female; mean age 56 years) were scanned on a 192-slice CT scanner with a standard-dose (ND) and a RD chest-CT protocol using tube current modulation. Image-noise was evaluated by placing circular regions of interest in the apical, middle, and lower lung regions. Two independent readers evaluated image quality. Study population was stratified according to patient position in the gantry: positioned in the gantry isocenter (i), higher than the gantry isocenter (ii), and lower than the gantry isocenter, (iii). Pearson correlation was used to determine the correlation between effective radiation dose and vertical off-centering. Student's t test was used to evaluate for differences in image-noise between groups (i-iii). RESULTS: Mean vertical off-centering was of 10.6 mm below the gantry-isocenter (range -45.0-27.9 mm). Effective radiation dose varied in a linear trend, with the highest doses noted below gantry isocenter, and the lowest doses noted above gantry isocenter (ND: r = -0.296; p = 0.003 - RD: r = -0.258; p = 0.010). Lowest image-noise was observed where patients were positioned below the gantry isocenter, and highest in patients positioned above (ND: 79.35 HU vs. 94.86 HU - RD: 143.44 HU vs. 160.13 HU). Subjective image quality was not significantly affected by patient-position (p > 0.05). Overall, there was no over-proportional noise-increase from the ND to the RD protocol in patients which were positioned off-center. CONCLUSION: Vertical off-centering influences effective radiation dose and image-noise on ND and RD protocols. ADVANCES IN KNOWLEDGE: There is no over-proportional noise increase in RD compared to ND protocols when patients are positioned off-center.

Diagnostic Accuracy of a MR Protocol Acquired with and without Endorectal Coil for Detection of Prostate Cancer: A Multicenter Study.

INTRODUCTION: The purpose of this study was to compare diagnostic accuracy of a prostate multiparametric magnetic resonance imaging (mpMRI) protocol for detection of prostate cancer between images acquired with and without en-dorectal coil (ERC). MATERIALS: This study was approved by the regional ethics committee. Between 2014 and 2015, 33 patients (median age 51.3 years; range 42.1-77.3 years) who underwent prostate-MRI at 3T scanners at 2 different institutions, acquired with (mpMRIERC) and without (mpMRIPPA) ERC and who received radical prostatectomy, were included in this retrospective study. Two expert readers (R1, R2) attributed a PI-RADS version 2 score for the most suspect (i. e. index) lesion for mpMRIPPA and mpMRIERC. Sensitivity and positive predictive value for detection of index lesions were assessed using 2 × 2 contingency tables. Differences between groups were tested using the McNemar test. Whole-mount histopathology served as reference standard. RESULTS: On a quadrant-basis cumulative sensitivity ranged between 0.61-0.67 and 0.76-0.88 for mpMRIPPA and mpMRIERC protocols, respectively (p > 0.05). Cumulative positive predictive value ranged between 0.80-0.81 and 0.89-0.91 for mpMRIPPA and mpMRIERC protocols, respectively. The differences were not statistically significant for R1 (p = 0.267) or R2 (p = 0.508). CONCLUSION: Our results suggest that there may be no significant differences for detection of prostate cancer between images acquired with and without an ERC.

Dynamic MRI of the pelvic floor: comparison of performance in supine vs left lateral body position.

OBJECTIVE:: To investigate the performance of MR-defecography (MRD) in lateral body position as an alternative to supine position. METHODS:: 22 consecutive patients (16 females; mean age 51 ± 19.4) with obstructed defecation and 20 healthy volunteers (11 females; mean age 33.4 ± 11.5) underwent MRD in a closed-configuration 3T-MRI in supine and lateral position. MRD included T2 weighted images at rest and during defecation after filling the rectum with 250 ml water-based gel. Measurements were performed in reference to the pubococcygeal line and grade of evacuation was assessed. Image quality (IQ) was rated on a 5-point-scale (5 = excellent). RESULTS:: In patients grades of middle and posterior compartment descent were similar in both body positions (p > 0.05). Grades of anterior compartment descent were significantly higher in lateral position (21/22 vs 17/22 patients with normal or small descent, p < 0.034). In volunteers grades of descent were similar for all compartments in supine and lateral position (p > 0.05). When attempting to defecate in supine position 6/22 (27%) patients showed no evacuation, while in lateral position only 3/22 (14%) were not able to evacuate. IQ in patients was equal at rest (4.4 ± 0.5 and 4.7 ± 0.6, p > 0.05) and slightly better in supine compared to the lateral position during defecation (4.5 ± 0.4 vs 3.9 ± 0.9, p < 0.017). IQ in volunteers was equal in supine and lateral position (p > 0.05). CONCLUSION:: In lateral position, more patients were able to evacuate with similar grades of pelvic floor descent compared to supine position. MRD in lateral position may be a valuable alternative for patients unable to defecate in supine position. ADVANCES IN KNOWLEDGE:: In lateral position, more patients were able to evacuate during MRD. MRD in lateral position may be an alternative for patients unable to defecate in supine position.

How to define pathologic pelvic floor descent in MR defecography during defecation?

OBJECTIVES: To assess the extents of pelvic floor descent both during the maximal straining phase and the defecation phase in healthy volunteers and in patients with pelvic floor disorders, studied with MR defecography (MRD), and to define specific threshold values for pelvic floor descent during the defecation phase. MATERIAL AND METHODS: Twenty-two patients (mean age 51 ± 19.4) with obstructed defecation and 20 healthy volunteers (mean age 33.4 ± 11.5) underwent 3.0T MRD in supine position using midsagittal T2-weighted images. Two radiologists performed measurements in reference to PCL-lines in straining and during defecation. In order to identify cutoff values of pelvic floor measurements for diagnosis of pathologic pelvic floor descent [anterior, middle, and posterior compartments (AC, MC, PC)], receiver-operating characteristic (ROC) curves were plotted. RESULTS: Pelvic floor descent of all three compartments was significantly larger during defecation than at straining in patients and healthy volunteers (p < 0.002). When grading pelvic floor descent in the straining phase, only two healthy volunteers showed moderate PC descent (10%), which is considered pathologic. However, when applying the grading system during defecation, PC descent was overestimated with 50% of the healthy volunteers (10 of 20) showing moderate PC descent. The AUC for PC measurements during defecation was 0.77 (p = 0.003) and suggests a cutoff value of 45 mm below the PCL to identify patients with pathologic PC descent. With the adapted cutoff, only 15% of healthy volunteers show pathologic PC descent during defecation. CONCLUSION: MRD measurements during straining and defecation can be used to differentiate patients with pelvic floor dysfunction from healthy volunteers. However, different cutoff values should be used during straining and during defecation to define normal or pathologic PC descent.

Image Quality and Geometric Distortion of Modern Diffusion-Weighted Imaging Sequences in Magnetic Resonance Imaging of the Prostate.

PURPOSE: The aim of this study was to compare qualitative and quantitative image quality and geometric distortion of 4 magnetic resonance diffusion-weighted imaging (DWI) sequences of the prostate using comparable imaging parameters and similar acquisition times. METHODS AND MATERIALS: Axial T2-weighted turbo spin echo images and axial DWI echo-planar imaging (EPI) sequences, including single-shot spin-echo (ss-EPI), readout-segmented multishot (rs-EPI), selective excitation-reduced field of view (sTX-EPI), and prototype single-shot technique applying slice-specific shimming (iShim-EPI) sequences, were acquired at 3 T in 10 healthy volunteers (mean age, 26.1 ± 3.8 years; body mass index, 23.2 ± 3.0 kg/m). Two radiologists, blinded to the type of DWI, independently rated DWIs on a 5-point Likert scale regarding subjective image quality features (resolution, demarcation of prostate capsule, zonal anatomy). Interreader agreement was assessed using the intraclass correlation coefficient. Signal-to-noise ratio (SNR) and apparent diffusion coefficient (ADC) values were assessed separately in the peripheral and transitional zone. For the analysis of geometric distortion, the diameter of the prostate from left to right and from anterior to posterior was measured at the level of the verumontanum on b-1000 DWIs and on T2-weighted turbo spin echo images. Differences were compared using the Wilcoxon rank sum test for qualitative parameters, analysis of variance, and Friedman test for quantitative parameters. A P value of less than 0.05 was considered significant, with correction for multiple comparisons. RESULTS: Interreader agreement was good to excellent (intraclass correlation coefficient, 0.71-0.79) for all qualitative features. Subjective image quality regarding "resolution" was significantly better for ss-EPI than rs-EPI (mean Likert score, 4.25 vs 3.8; P = 0.031) and sTX-EPI (4.25 vs 3.3; P = 0.046) and for iShim-EPI as compared with rs-EPI (4.4 vs 3.8; P = 0.031) and sTX-EPI (4.4 vs 3.3; P = 0.047). There was no significant difference regarding capsule demarcation and zonal anatomy. Signal-to-noise ratio was significantly higher in iShim-EPI than sTX-EPI (SNR ± standard deviation [SD], 28.13 ± 8.21 vs 14.96 ± 2.4; P = 0.015). The ADC values were lower for the peripheral zone in the sTX-EPI than in the ss-EPI (ADC ± SD, 1002.94 ± 83.51 vs 1165.05 ± 115.64; P = 0.013) and the rs-EPI (1002.94 ± 83.51 vs 1244.40 ± 89.95; P = 0.0012) and in the transitional zone in the sTX-EPI compared with the rs-EPI (874.50 ± 200.72 vs 1261.47 ± 179.23; P = 0.0021). There were no statistically significant differences in geometric distortion between all DWI sequences. CONCLUSIONS: Single-shot spin-echo EPI and iShim-EPI showed a tendency toward superior image quality and SNR compared with rs-EPI and sTX-EPI with no significant differences in geometric distortion.

Direct comparison of PI-RADS version 2 and version 1 regarding interreader agreement and diagnostic accuracy for the detection of clinically significant prostate cancer.

PURPOSE: to simultaneously evaluate interreader agreement and diagnostic accuracy in the of PI-RADS v2 and compare it to v1. METHODS: A total of 67 patients (median age 65.3 y, range 51.2-78.2 y; PSA 6.8µg/L, 0.2-33µg/L) undergoing MRI of the prostate and subsequent transperineal template biopsy within ≤6 months from MRI were included. Four readers from two institutions evaluated the likelihood of prostate cancer using PI-RADS v1 and v2 in two separate reading sessions ≥3 months apart. Interreader agreement was assessed for each pulse-sequence and for total PI-RADS scores using the intraclass correlation coefficient (ICC). Differences were considered significant for non-overlapping 95%-confidence intervals. Diagnostic accuracy was assessed with the area under the receiver operating characteristic curve (AZ). A p-value <0.05 was considered statistically significant. RESULTS: Interreader agreement for DCE-scores was good in v2 (ICC2=0.70; 95% CI: 0.66-0.74) and slightly lower in v1 (ICC1=0.64, 0.59-0.69). Agreement for DWI scores (ICC1=0.77, ICC2=0.76) as well as final PI-RADS scores per quadrant were nearly identical (ICC1=ICC2=0.71). Diagnostic accuracy showed no significant differences (p=0.09-0.93) between v1 and v2 in any of the readers (range: AZ=0.78-0.88). CONCLUSION: PI-RADS scores show similar interreader agreement in v2 and v1 at comparable diagnostic performance. The simplification of the DCE interpretation in v2 might slightly improve agreement while not negatively affecting diagnostic performance.

Combined intra- and extraperitoneal urinary bladder rupture - a rare seat-belt injury: A case report.

INTRODUCTION: While isolated traumatic urinary bladder injuries are rare, combined intra- and extraperitoneal traumatic urinary bladder ruptures without an underlying fracture are an absolute rarity. PRESENTATION OF CASE: We report a case of combined intra- and extraperitoneal urinary bladder rupture without an underlying fracture resulting from blunt abdominal trauma during a high velocity car accident. A midline laparotomy was performed, and the intra- and extraperitoneal bladder ruptures were surgically treated. DISCUSSION: Based on the presented case the anatomical peculiarities of the urinary bladder and the different trauma mechanisms as well as the resulting lesions, the diagnostic modalities and the treatment options are discussed. CONCLUSION: Despite the rarity of traumatic urinary bladder injuries, and especially in the absence of an underlying fracture, physicians should maintain a high level of suspicion for urologic injuries in the presence of nonspecific lower abdominal pain, gross haematuria and the inability to urinate.

Detection of Clinically Significant Prostate Cancer: Short Dual-Pulse Sequence versus Standard Multiparametric MR Imaging-A Multireader Study.

Purpose To compare the diagnostic performance of a short dual-pulse sequence magnetic resonance (MR) imaging protocol versus a standard six-pulse sequence multiparametric MR imaging protocol for detection of clinically significant prostate cancer. Materials and Methods This HIPAA-compliant study was approved by the regional ethics committee. Between July 2013 and March 2015, 63 patients from a prospectively accrued study population who underwent MR imaging of the prostate including transverse T1-weighted; transverse, coronal, and sagittal T2-weighted; diffusion-weighted; and dynamic contrast material-enhanced MR imaging with a 3-T imager at a single institution were included in this retrospective study. The short MR imaging protocol image set consisted of transverse T2-weighted and diffusion-weighted images only. The standard MR imaging protocol image set contained images from all six pulse sequences. Three expert readers from different institutions assessed the likelihood of prostate cancer on a five-point scale. Diagnostic performance on a quadrant basis was assessed by using areas under the receiver operating characteristic curves, and differences were evaluated by using 83.8% confidence intervals. Intra- and interreader agreement was assessed by using the intraclass correlation coefficient. Transperineal template saturation biopsy served as the standard of reference. Results At histopathologic evaluation, 84 of 252 (33%) quadrants were positive for cancer in 38 of 63 (60%) men. There was no significant difference in detection of tumors larger than or equal to 0.5 mL for any of the readers of the short MR imaging protocol, with areas under the curve in the range of 0.74-0.81 (83.8% confidence interval [CI]: 0.64, 0.89), and for readers of the standard MR imaging protocol, areas under the curve were 0.71-0.77 (83.8% CI: 0.62, 0.86). Ranges for sensitivity were 0.76-0.95 (95% CI: 0.53, 0.99) and 0.76-0.86 (95% CI: 0.53, 0.97) and those for specificity were 0.84-0.90 (95% CI: 0.79, 0.94) and 0.82-0.90 (95% CI: 0.77, 0.94) for the short and standard MR protocols, respectively. Ranges for interreader agreement were 0.48-0.60 (83.8% CI: 0.41, 0.66) and 0.49-0.63 (83.8% CI: 0.42, 0.68) for the short and standard MR imaging protocols. Conclusion For the detection of clinically significant prostate cancer, no difference was found in the diagnostic performance of the short MR imaging protocol consisting of only transverse T2-weighted and diffusion-weighted imaging pulse sequences compared with that of a standard multiparametric MR imaging protocol. © RSNA, 2017 Online supplemental material is available for this article.

Traumatic nonanastomotic axilloprofundal PTFE-bypass rupture: a case report.

A 76-year-old male patient was admitted to our emergency department with painful swelling of the right lateral chest after a fall. Imaging revealed a hematoma, secondary to rupture of a synthetic axilloprofundal bypass. In an emergency surgical procedure, the spelled hematoma was evacuated and the graft legs were successfully ligated. The patient was discharged after an uneventful hospital stay. Traumatic bypass rupture because of blunt trauma is an exceedingly rare event; however, it must be taken into consideration in a patient with bypass surgery in his/her history.

Increased interreader agreement in diagnosis of hepatocellular carcinoma using an adapted LI-RADS algorithm.

PURPOSE: To evaluate a simplified Liver Imaging Reporting and Data System (LI-RADS) algorithm to improve interreader agreement while maintaining diagnostic performance for HCC. MATERIALS AND METHODS: MRI scans of 84 cirrhotic patients with 104 distinct liver observations were retrospectively selected to equivocally match each of the LI-RADS grades (LR1-5) using histopathology and imaging follow up as standard of reference. Four independent radiologists categorized all observations as benign (LR1-2) or potentially malignant (LR3-5) and determined LI-RADS based imaging features including observation size, arterial phase hyperenhancement, washout, capsule appearance and threshold growth for LR3-5 observations and timed their readouts. LR3-5 observations were categorized according to the LI-RADS v2014 algorithm and according to a modified LI-RADS (mLI-RADS) version. Diagnostic performance and Interreader agreement were determined for LI-RADS and mLI-RADS using receiver operating characteristics (ROC) and Fleiss' and Cohen's Kappa analysis respectively. RESULTS: ROC analysis revealed equal diagnostic performance for LI-RADS and mLI-RADS (area under the ROC curve=0.91). Interreader agreement was higher using mLI-RADS as compared to current LI-RADS showing an improved overall (κ=0.53±0.04 vs. 0.45±0.04), and pair-wise agreement between most readers (κ range 0.44-0.62 vs. 0.35-0.60) at a reduced median evaluation time (51 vs. 62s per observation, p<0.0001). CONCLUSION: Focusing on observation size and washout criteria using a modified, stepwise LI-RADS decision tree for LR3-5 observations results in higher interobserver reliability and faster categorization while maintaining diagnostic accuracy.

Simultaneous Multislice Diffusion-Weighted Imaging of the Kidney: A Systematic Analysis of Image Quality.

OBJECTIVES: The aims of this study were to implement a protocol for simultaneous multislice (SMS) accelerated diffusion-weighted imaging (DWI) of the kidneys and to perform a systematic analysis of image quality of the data sets. MATERIALS AND METHODS: Ten healthy subjects and 5 patients with renal masses underwent DWI of the kidney in this prospective institutional review board-approved study on a 3 T magnetic resonance scanner. Simultaneous multislice DWI echo-planar sequences (acceleration factors [AFs] 2 and 3) were compared with conventional echo-planar DWI as reference standard for each acquisition scheme. The following 3 acquisition schemes were applied: comparison A, with increased number of acquisitions at constant scan time; comparison B, with reduction of acquisition time; and comparison C, with increased slice resolution (constant acquisition time, increasing number of slices). Interreader reliability was analyzed by calculating the intraclass correlation coefficient (ICC). Qualitative image quality features were evaluated by 2 independent radiologists on a 5-point Likert scale. Quantification accuracy of the apparent diffusion coefficients (ADCs) and signal-to-noise ratios (SNRs) were assessed by region of interest analysis. Furthermore, lesion conspicuity in the 5 patients was assessed using a 5-point Likert scale by 2 independent radiologists. RESULTS: Interreader agreement was substantial with an ICC of 0.68 for the overall image quality and an ICC of 0.73 for the analysis of artifacts. In comparison A, AF2 resulted in increased SNR (P < 0.05) by 21% at stable image quality scores (image quality: P = 0.76, artifacts: P = 0.21). In comparison B, applying AF2, the scan time could be reduced by 46% without significant reduction in qualitative image quality scores (P = 0.059) or SNR (P = 0.126). In comparison C, slice resolution could be improved by 28% using AF2 with stable image quality scores and SNR. In general, AF3 resulted in reduced image quality and SNR. Significantly reduced ADC values were observed for AF3 in comparison C (cortex: P = 0.003; medulla: P = 0.001) compared with the standard echo-planar imaging sequence. The conventional DWI and the SMS DWI with AF2 showed stable lesion conspicuity ([AF1/AF2]: reader 1 [1.8/1.4] and reader 2 [1.8/1.4]). The lesion conspicuity was lower using AF3 (reader 1: 2.2 and reader 2: 1.8). CONCLUSIONS: In conclusion, SMS DWI of the kidney is a potential tool to substantially reduce scan time without negative effects on SNR, ADC quantification accuracy, and image quality if an AF2 is used. Although AF3 results in even higher scan time reduction, a negative impact on image quality, SNR, ADC quantification accuracy, and lesion conspicuity must be considered.

Dose-Optimized Computed Tomography for Screening and Follow-Up of Solid Pulmonary Nodules in Obesity: A Phantom Study.

To determine the lowest CT radiation dose-level at maintained image-quality and high sensitivity for detection of pulmonary-nodules in obesity. Single-energy CT with tin-filtration was performed in a chest-phantom with solid pulmonary-nodules simulating over-weight and obesity. CTDIvol of the standard-protocol was 0.41 mGy, subsequent scans were obtained at 1/2 and 1/4 dose-levels. Images were reconstructed using FBP and advanced-modeled iterative reconstruction (ADMIRE). Noise, image-quality, and sensitivity for nodule-detection were assessed. Noise was significantly reduced with ADMIRE (standard-dose: 73%; 1/2 dose: 73%; 1/4 dose: 71.2%; p < 0.001) compared to FBP. Image-quality was diagnostic for all images reconstructed with ADMIRE5. Sensitivity for nodule-detection was 100% at 1/2 and 1/4 dose-level for the phantom simulating over-weight and 97.37% (1/2 dose-level) and 81.58% (1/4 dose-level) for the phantom simulating obesity using ADMIRE5. In conclusion, single-energy CT with tin-filtration and ADMIRE shows potential for dose reduction in a phantom experiment down to 0.1 mGy in over-weight and 0.21 mGy obese subjects, while image quality and sensitivity for detection of solid pulmonary nodules remains high.

Comparison of image quality and patient discomfort in prostate MRI: pelvic phased array coil vs. endorectal coil.

PURPOSE: To compare image quality (IQ) and patient discomfort during prostate MRI using a pelvic phased array (PPA) coil and an endorectal (ER) coil. MATERIALS AND METHODS: Ninety-eight patients (median age, 65.7; range 42.1-78.1) underwent prostate MRI on a 3T scanner including T2w and DWI acquired with PPA and an ER coil within the same exam. Acquisition time was kept similar for both acquisitions. Two radiologists evaluated aspects of IQ on a 5-point Likert scale and classified image artifacts. All patients completed a questionnaire on discomfort/pain regarding the ER coil using a visual analogue scale from 1 to 10. RESULTS: There was no significant difference in overall IQ for T2w images for both readers (reader 1, 3.27 ± 0.91 and 3.07 ± 0.84, p = 0.057; reader 2, 3.70 ± 0.75 and 3.77 ± 0.81, p = 0.555) for PPA and ER coils, respectively. Overall IQ for DWI acquired with PPA and ER coils was rated similar by reader 1 (3.03 ± 1.10 and 3.08 ± 0.80, respectively, (p = 0.67)), while reader 2 preferred ER coil images (3.27 ± 0.81 and 3.66 ± 0.85 (p < 0.05)). Susceptibility artifacts were more frequent in ER than in PPA coil images (109 vs. 75). Discomfort and pain experienced during insertion of the ER coil was low altogether (VAS score, 3.5 ± 2.1 for "discomfort" and 2.4 ± 2.4 for "pain"). CONCLUSION: T2-weighted images may be acquired with comparable IQ using a PPA coil as compared to an ER coil, while DWI images showed better IQ using the ER coil for one of two readers. The insertion of the ER coil caused low to moderate discomfort and pain in patients.

Reliability, Validity, and Reader Acceptance of LI-RADS-An In-depth Analysis.

RATIONALE AND OBJECTIVES: This study aimed to analyze interreader agreement and diagnostic accuracy of Liver Imaging Reporting and Data System (LI-RADS) in comparison to a nonstandardized 5-point scale and to assess reader acceptance of LI-RADS for clinical routine. MATERIALS AND METHODS: Eighty-four consecutive patients at risk for hepatocellular carcinoma who underwent liver magnetic resonance imaging were included in this Health Insurance Portability and Accountability Act-compliant retrospective study. Four readers rated the likelihood of hepatocellular carcinoma for 104 liver observations using LI-RADS criteria and a 5-point Likert scale (LIKERT) based on subjective impression in two separate reading sessions. Interreader agreement was assessed using kappa statistics (κ). Diagnostic accuracy was assessed with receiver operating characteristic analysis. Reader acceptance was evaluated with a questionnaire. A sub-analysis of LI-RADS's major features (arterial phase hyper-enhancement, washout, capsule appearance, and threshold growth) and scores for lesions 1.5 cm was performed. RESULTS: LI-RADS showed similar overall interreader agreement compared to LIKERT (κ, 0.44 [95%CI: 0.37, 0.52] and 0.35 [95%CI: 0.27, 0.43]) with a tendency toward higher interreader agreement for LI-RADS. Interreader agreement (κ) was 0.51 (95%CI: 0.38, 0.65) for arterial phase hyper-enhancement, 0.52 (95%CI: 0.39, 0.65) for washout, 0.37 (95%CI: 0.23, 0.52) for capsule appearance, and 0.50 (95%CI: 0.38, 0.61) for threshold growth. Overall interreader agreement for LI-RADS categories was similar between observations <1.5 cm and observations >1.5 cm. Overall diagnostic accuracy for LIKERT and LI-RADS was comparable (area under the receiver operating characteristic curve, 0.86 and 0.87). Readers fully agreed with the statement "A short version of LI-RADS would facilitate the use in clinical routine" (median, 5.0; interquartile range, 2.25). CONCLUSIONS: LI-RADS showed similar interreader agreement and diagnostic accuracy compared to nonstandardized reporting. However, further reduction of complexity and refinement of imaging features may be needed.