Detectability of Hypoattenuating Liver Lesions with Deep Learning CT Reconstruction: A Phantom and Patient Study.

Background CT deep learning image reconstruction (DLIR) improves image quality by reducing noise compared with adaptive statistical iterative reconstruction-V (ASIR-V). However, objective assessment of low-contrast lesion detectability is lacking. Purpose To investigate low-contrast detectability of hypoattenuating liver lesions on CT scans reconstructed with DLIR compared with CT scans reconstructed with ASIR-V in a patient and a phantom study. Materials and Methods This single-center retrospective study included patients undergoing portal venous phase abdominal CT between February and May 2021 and a low-contrast-resolution phantom scanned with the same protocol. Four reconstructions (ASIR-V at 40% strength [ASIR-V 40] and DLIR at three strengths) were generated. Five radiologists qualitatively assessed the images using the five-point Likert scale for image quality, lesion diagnostic confidence, conspicuity, and small lesion (≤1 cm) visibility. Up to two key lesions per patient, confirmed at histopathologic testing or at prior or follow-up imaging studies, were included. Lesion-to-background contrast-to-noise ratio was calculated. Interreader variability was analyzed. Intergroup qualitative and quantitative metrics were compared between DLIR and ASIR-V 40 using proportional odds logistic regression models. Results Eighty-six liver lesions (mean size, 15 mm ± 9.5 [SD]) in 50 patients (median age, 62 years [IQR, 57-73 years]; 27 [54%] female patients) were included. Differences were not detected for various qualitative low-contrast detectability metrics between ASIR-V 40 and DLIR (P > .05). Quantitatively, medium-strength DLIR and high-strength DLIR yielded higher lesion-to-background contrast-to-noise ratios than ASIR-V 40 (medium-strength DLIR vs ASIR-V 40: odds ratio [OR], 1.96 [95% CI: 1.65, 2.33]; high-strength DLIR vs ASIR-V 40: OR, 5.36 [95% CI: 3.68, 7.82]; P < .001). Low-contrast lesion attenuation was reduced by 2.8-3.6 HU with DLIR. Interreader agreement was moderate to very good for the qualitative metrics. Subgroup analysis based on lesion size of larger than 1 cm and 1 cm or smaller yielded similar results (P > .05). Qualitatively, phantom study results were similar to those in patients (P > .05). Conclusion The detectability of low-contrast liver lesions was similar on CT scans reconstructed with low-, medium-, and high-strength DLIR and ASIR-V 40 in both patient and phantom studies. Lesion-to-background contrast-to-noise ratios were higher for DLIR medium- and high-strength reconstructions compared with ASIR-V 40. © RSNA, 2024 Supplemental material is available for this article.

Utility of CT and MRI in Tricuspid Valve Interventions.

Transcatheter tricuspid valve interventions (TTVIs) comprise a variety of catheter-based interventional techniques for treatment of tricuspid regurgitation (TR) in patients at high surgical risk and those with failed previous surgeries. Several TTVI devices with different mechanisms of action are either currently used or in preclinical evaluation. Echocardiography is the first-line modality for evaluation of tricuspid valve disease that provides information on tricuspid valve morphology, mechanism of TR, and hemodynamics. Cardiac CT and MRI have several advantages for a comprehensive preprocedure evaluation. CT and MRI provide complementary information to that of echocardiography on the mechanism and cause of TR. MRI can quantify the severity of TR using indirect or direct techniques that involve two-dimensional or four-dimensional flow sequences. MRI and CT can also accurately quantify right ventricular volumes and function, which is crucial for timing of intervention. CT provides comprehensive three-dimensional information on the morphology of the valve, annulus, subvalvular apparatus, and adjacent structures. CT is the procedure of choice for evaluation of several device-specific measurements, including tricuspid annulus dimensions, annulus-to-right coronary artery distance, leaflet morphology, coaptation gaps, caval dimensions, and cavoatrial-to-hepatic vein distance. CT allows evaluation of the vascular access as well as optimal procedure fluoroscopic angles and catheter trajectory. Postprocedure CT and MRI are useful in detection of complications such as paravalvular leak, pseudoaneurysm, thrombus, pannus, infective endocarditis, and device migration. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

"All-in-one" window/level whole-body computed tomography scan - A faster way to evaluate trauma cases.

PURPOSE: To investigate the accuracy and total assessment time (TAT) of the "All-in-one" (AIO)-window/level setting for whole-body computed tomography (CT) image compared to multiple tissue-specific window/level settings conventionally used for detection of traumatic injuries. METHOD: Contrast-enhanced chest, abdomen, and pelvic CT scans of 50 patients who presented to our emergency department (ED) for major trauma were retrospectively selected. In a simulation of a "wet read" performed at the CT scanner console, 6 readers with different levels of experience had up to 3 min to describe any traumatic finding identified on the CTs. The readers reviewed each patient in two different sessions separated by a washout period to suppress any recall bias from one session to the next. Each scan was reviewed once using the AIO-window/level setting and another time using the conventional bone, lung, and soft tissue window/level display settings, in a randomized order. The CT reports were used as reference standard. RESULTS: Overall, there was no statistically significant difference in the assessment accuracy of the review based on the AIO or the conventional window/level settings (0.89 ± 0.09 vs 0.90 ± 0.08). Using the AIO-window/level settings, TAT was 14.3 s faster when compared with the conventional window/level settings (2.33 ± 0.63 vs 2.57 ± 0.51 min; p < 0.001). CONCLUSIONS: In a time-delimited image review, similar diagnostic accuracy was reached faster using the AIO vs the conventional window/level settings. When providing a "wet read" at the CT console, the ability to identify traumatic injury using a single AIO-window/level may help expedite patient management.

Multicentric study of patients receiving 50 or 100 mSv in a single day through CT imaging-frequency determination and imaging protocols involved.

OBJECTIVES: To assess the magnitude and characterization of CT imaging protocols of patients receiving 50 or 100 mSv in a single day. METHODS: In this multicentric retrospective study covering up to 279 hospitals from January 2015 to December 2019, the effective dose (E) as estimated by dose management system from dose length product of patients was filtered and grouped into per-day dose bands (≤ 20, > 20-50, > 50-70, > 70-100, > 100-200, > 200 mSv). Information on patient's age and imaging protocol was noted. The data were analyzed to determine the frequency of occurrence in each dose band. Top 20 CT imaging protocols that led to patients with a dose of ≥ 50 mSv in a single acquisition were identified and their relative frequency was estimated. RESULTS: A total of approx. 4.3 million (4,283,738) CT exams were performed in approx. 3.9 million (3,880,524) patient-days indicating 9.41% had more than one CT exam in a single day. There were 31,058 (0.8%) patient-days with ≥ 50 mSv and 1191 (0.03%) with ≥ 100 mSv. Nearly 1/3rd patient-days reaching ≥ 50 mSv were of patients aged 50 years or younger. The top 20 CT imaging protocols that led to ≥ 50 mSv in a single day belonged to the body region (chest or abdomen and pelvis) and nearly one-third were angiographic studies. CONCLUSIONS: In the first study of its kind, we report that patients with 50 mSv+ in a single day or a single exam are not rare. The information on imaging protocols leading to such doses and their frequency has been provided to help develop dose management strategies. KEY POINTS: • Our study of 4,283,738 CT exams performed in 3,880,524 patient-days indicates 0.8% with 50 mSv+ and 0.03% with 100 mSv+ in a single day. • A total of 9.41% underwent more than one CT exam in a single day; nearly 1/3rd of those with 50 mSv+ were ≤ 50 years of age. • Identified top 20 CT imaging protocols that led to 50 mSv+ doses in a single exam. All belong to chest or abdomen and pelvis and nearly 1/3rd were angiographic studies.

Hepatobiliary phase enhancement of liver metastases on gadoxetic acid MRI: assessment of frequency and patterns.

OBJECTIVES: To assess for and characterize patterns of hepatobiliary phase (HBP) enhancement in hepatic metastases of various malignancies on gadoxetic acid-enhanced MRI. METHODS: Eighty gadoxetic acid-enhanced MRI studies performed between July 2012 and November 2019 in patients with hepatic metastases from 13 different primary malignancies were assessed. Most (n = 60) were from colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDAC), or neuroendocrine tumor (NET) primaries. Two radiologists quantitatively evaluated the dominant lesion on each MRI. A lesion was considered enhancing when HBP enhancement relative to muscle exceeded 20%. Lesions were classified by pattern of enhancement. Quantitative enhancement metrics and patterns of enhancement were compared between CRC, PDAC, and NET using non-parametric statistical tests. RESULTS: Most dominant metastatic lesions > 1 cm (77%, 54/70) demonstrated HBP enhancement. HBP enhancement was identified in hepatic metastases from 10 different primary malignancies, including CRC, PDAC, and NET. PDAC metastases demonstrated a lower degree of HBP enhancement (26%) than CRC (44%, padj = 0.04) and NET (51%, padj = 0.01) metastases. Three discrete enhancement patterns were identified: peripheral, central (target), and diffuse heterogeneous. Patterns of HBP enhancement varied between CRC, PDAC, and NET, with secondary analysis demonstrating that PDAC had the highest proportion of peripheral pattern (73%, padj < 0.001), CRC the highest proportion of diffuse heterogeneous pattern (32%, padj < 0.01), and NET the highest proportion of central pattern (89%, padj < 0.001). CONCLUSION: Liver metastases from several primary malignancies, including PDAC, demonstrate mild HBP enhancement in variable patterns. Correlation with OATP1B3 expression and prognosis is required. KEY POINTS: • Hepatobiliary phase (HBP) enhancement was identified in 77% of hepatic metastases in several different primary malignancies. • Discrete patterns of HBP enhancement exist (peripheral, central, diffuse heterogeneous) and varied between CRC, PDAC, and NET. CRC and PDAC metastases demonstrated mostly non-central patterns (diffuse and peripheral), and NET mostly a central pattern. • Relationship between HBP enhancement, enhancement pattern, OATP1B3 expression, and prognosis requires further dedicated exploration for each malignancy.

Hepatobiliary contrast uptake patterns on gadoxetic acid-enhanced MRI in liver metastases from pancreatic ductal adenocarcinoma: can it predict prognosis?

OBJECTIVES: To evaluate the relationship between the patterns of hepatobiliary phase (HBP) contrast uptake in liver metastases on gadoxetic acid-enhanced MR imaging and overall survival (OS) in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: This retrospective study was approved by our institutional review board and written informed consent was waived. A total of 57 patients (30 men and 27 women; age range, 46-92 years; mean age, 64.9 ± 9.2 years) with PDAC and liver metastasis who had undergone gadoxetic acid-enhanced MR imaging were included. The internal morphologies of the nodules were classified as heterogeneous or homogeneous on HBP images (20 min). During patient-by-patient analysis, patients with both patterns of nodules were classified as belonging to the heterogeneous group. Kaplan-Meier analysis and log-rank test were conducted for univariate analysis and Cox proportional hazards regression was conducted for multivariate analysis to evaluate prognostic factors for OS in patients with PDAC and liver metastasis. RESULTS: A total of 199 liver metastases were analyzed, among which 138 nodules (69%) demonstrated heterogeneous hypointensity, while 61 nodules (31%) demonstrated homogeneous hypointensity. Homogeneous hypointense nodules were encountered in 18 patients (32%; homogeneous group), heterogeneous in 29 patients (51%), and both patterns co-existed in 10 patients (17%; heterogeneous group). The heterogeneous group exhibited lower OS rates than the homogeneous group (mean OS, 48.5 months vs 23.9 months; p = 0.032). CONCLUSIONS: Hepatobiliary contrast uptake pattern in liver metastasis on HBP images can be a potential imaging biomarker to predict OS in patients with PDAC and liver metastasis. KEY POINTS: • Majority of the liver metastases were heterogeneous (69%) after gadoxetic acid-enhanced MR imaging. • Patients with heterogeneous hypointense nodules demonstrated lower overall survival rate. • Hepatobiliary contrast uptake pattern in liver metastasis is possibly associated with patients' prognosis.

Dual-Source Dual-Energy CT in Detection and Characterization of Urinary Stones in Patients With Large Body Habitus: Observations in a Large Cohort.

OBJECTIVE: The objective of our study was to investigate the impact of large body habitus on dual-energy CT (DECT) image quality and stone characterization. MATERIALS AND METHODS: We retrospectively included 105 consecutive patients with large body habitus (> 90 kg) who underwent stone protocol DECT between 2015 and 2017. The evaluation of DECT datasets was performed for image quality assessment based on European Guidelines on Quality Criteria for Computed Tomography and for determination of stone composition (i.e., uric acid vs non-uric acid). Correlation between DECT characterization and crystallography results was performed when available. The cohort was divided into two groups on the basis of body weight (≤ 104 kg and > 104 kg), and comparisons were made for image quality and stone characterization. RESULTS: One hundred ninety-seven urinary tract calculi (size: mean ± SD, 5.7 ± 5.3 mm; range, 1.4-56 mm) were detected in 73% (79/108) of examinations in 105 patients (weight: mean ± SD, 104.0 ± 12.7 kg; range, 91-163 kg). The overall mean image quality score of blended images and color maps was 3.7 and 3.9, respectively, and the effective dual-energy FOV limitation did not hamper stone characterization. The diagnostic acceptability scores of blended images and color maps were slightly lower in patients weighing > 104 kg than in patients ≤ 104 kg (mean scores [highest score, 4 points]: blended images, 3.62 vs 3.82 [p = 0.0314]; color maps, 3.75 vs 3.98 [p = 0.0034]), but the scores were within acceptable range. Stone characterization as uric acid versus non-uric acid was achieved in 80% (158/197) of calculi (size: mean ± SD, 6.4 ± 5.7 mm; range, 1.6-56 mm), and DECT stone characterization was (95.6%) accurate with reference to crystallography. Twenty percent (39/197) of calculi could not be characterized on DECT, and these calculi were significantly smaller in size (size: mean ± SD, 2.8 ± 1.4 mm; range, 1.4-8.2 mm; p < 0.001) than those that could be characterized. The mean size of uncharacterized calculi was slightly larger in patients weighing > 104 kg (3.3 ± 1.6 mm) than in those weighing ≤ 104 kg (2.2 ± 0.6 mm). CONCLUSION: In patients with large body habitus, dual-source DECT provides acceptable image quality and allows characterization of almost all clinically significant calculi.

Perivascular Epicardial Fat Stranding at Coronary CT Angiography: A Marker of Acute Plaque Rupture and Spontaneous Coronary Artery Dissection.

Purpose To evaluate the frequency and implications of perivascular fat stranding on coronary computed tomography (CT) angiograms obtained for suspected acute coronary syndrome (ACS). Materials and Methods This retrospective registry study was approved by the institutional review board. The authors reviewed the medical records and images of 1403 consecutive patients (796 men, 607 women; mean age, 52.8 years) who underwent coronary CT angiography at the emergency department from February 2012 to March 2016. Fat attenuation, length and number of circumferential quadrants of the affected segment, and attenuation values in the unaffected epicardial and subcutaneous fat were measured. "Cases" were defined as patients with perivascular fat stranding. Patients with significant stenosis but without fat stranding were considered control subjects. Baseline imaging characteristics, ACS frequency, and results of subsequent downstream testing were compared between cases and control subjects by using two-sample t, Mann-Whitney U, and Fisher tests. Results Perivascular fat stranding was seen in 11 subjects, nine with atherosclerotic lesions and two with spontaneous coronary artery dissections, with a mean fat stranding length of 19.2 mm and circumferential extent averaging 2.9 quadrants. The mean attenuation of perivascular fat stranding, normal epicardial fat, and normal subcutaneous fat was 17, -93.2, and -109.3 HU, respectively (P < .001). Significant differences (P < .05) between cases and control subjects included lower Agatston score, presence of wall motion abnormality, and initial elevation of serum troponin level. ACS frequency was 45.4% in cases and 3.8% in control subjects (P = .001). Conclusion Recognition of perivascular fat stranding may be a helpful additional predictor of culprit lesion and marker of risk for ACS in patients with significant stenosis or spontaneous coronary artery dissection. © RSNA, 2018 Online supplemental material is available for this article.

Dual-Source Dual-Energy CT Portal Venous Phase Abdominal CT Scans in Large Body Habitus Patients: Preliminary Observations on Image Quality and Material Decomposition.

PURPOSE: Our objective was to evaluate image quality (IQ) and material decomposition in patients with large body habitus undergoing portal venous phase abdominal computed tomography (CT) scans on dual-source dual-energy CT (dsDECT) scanners. METHODS: This retrospective analysis included 30 scans from consecutive patients (19 males/11 females, mean ± SD age = 55.3 ± 17.5 years, range = 27-87 years) with large body habitus (≥90 kg, mean ± SD weight = 105.4 ± 12.35, range = 91-145 kg) who underwent portal venous phase abdominal DECT examinations on dsDECT scanner between Jan 2015 and Dec 2015. Qualitative and quantitative evaluation of IQ of DECT data sets (blended, iodine, and virtual noncontrast images) was performed. The patients were categorized into 2 groups (group A, ≤104 kg; group B, >104 kg). RESULTS: The mean ± SD patient body weight in group A was 97.2 ± 4.5 kg (range = 91-104 kg) and 114.8 ± 11.7 kg (range = 104.3-145.2 kg) for patients in group B. The diagnostic acceptability of the blended images in patients > 104 kg was lower (3.6 vs 4, <3 in 4/14 vs 0/16, P = 0.03). The extension of visceral anatomy beyond DE field of view (DEFOV) was seen in 60% (28 organs in 18 patients), the most common organs being liver and spleen. The incidence of visceral organs outside DEFOV was significantly higher in patients > 104 kg (18 vs 10, P = 0.03). Outside the DEFOV, blended images demonstrated higher image noise (mean: 14.48, range = 10.09-26.83 vs mean: 9.5, range = 7.3-15.8) P < 0.001) and lower signal-to-noise ratio (mean: 4.15, range = 1.5-7.6 vs mean: 7.5, range = 4.2-9.9) P < 0.001), and material-specific information was not available in this region. Within the DEFOV, the IQ of iodine maps and virtual non-contrast images were diagnostically acceptable with diagnostic acceptability of 3 or greater in nearly all patients. A 40-cm transverse diameter cut-off provided a good predictor of extension of visceral anatomy outside the effective DEFOV. CONCLUSIONS: Dual-source DECT allows diagnostically acceptable IQ and material separation in patients with large body habitus with the major limitation of exclusion of patient anatomy and organs outside the effective dual-energy field of view.

Image-guided urological interventions: What the urologists must know.

Advances in imaging technology, especially in the last two decades, have led to a paradigm shift in the field of image-guided interventions in urology. While the traditional biopsy and drainage techniques are firmly established, image-based stone management and endovascular management of hematuria have evolved further. Ablative techniques for renal and prostate cancer and prostate artery embolization for benign prostatic hypertrophy have evolved into viable alternative treatments. Many urologic diseases that were earlier treated surgically are now effectively managed using minimally invasive image-guided techniques, often on a day care basis using only local anesthesia or conscious sedation. This article presents an overview of the technique and status of various image-guided urological procedures, including recent emerging techniques.

Imaging of Visceral Vessels.

The visceral vasculature is inextricably intertwined with abdominopelvic disease staging, spread, and management in routine and emergent cases. Comprehensive evaluation requires specialized imaging techniques for abnormality detection and characterization. Vascular pathology is often encountered on nondedicated routine imaging examinations, which may obscure, mimic, or confound many vascular diagnoses. This review highlights normal arterial, portal venous, and systemic venous anatomy and clinically relevant variants; diagnostic pitfalls related to image-acquisition technique and disease mimics; and characteristics of common and rare vascular diseases to empower radiologists to confidently interpret the vascular findings and avoid misdiagnosis.

Role of Computed Tomography in Cardiac Electrophysiology.

With the increasing prevalence of arrhythmias, the use of electrophysiology (EP) procedures has increased. Recent advancements in computed tomography (CT) technology have expanded its use in pre-assessments and post-assessments of EP procedures. CT provides high-resolution images, is noninvasive, and is widely available. This article highlights the strengths and weaknesses of cardiac CT in EP.

Differential culprit plaque morphology in acute coronary syndrome: a comparison between very young patients (≤35 years) and older counterparts using optical coherence tomography.

Aims: Underlying mechanisms responsible for acute coronary syndrome (ACS) in young patients compared with older counterparts are yet to be explored with optical coherence tomography (OCT). This study aims to explore underlying mechanisms of ACS in ≤35- (very young) and >35-year-old (older counterparts) ACS patients using OCT. Methods and results: This was a prospective, single-centre, investigational study. Patients were divided into groups according to age (≤35 and >35 years) and further subdivided according to the underlying mechanism i.e. plaque rupture (PR) and plaque erosion (PE). A total of 93 patients were analysed. Thin-cap fibroatheroma (TCFA) was significantly higher among older counterparts than very young patients for both PR (80.0% vs. 31.8%, P = 0.002) and PE (66.7% vs. 6.3%, P < 0.001) groups. Microchannels were also significantly more prevalent among older than very young patients for both PR (65.0% vs. 18.2%, P = 0.004) and PE groups (55.6% vs.12.5%, P = 0.013). Macrophages were significantly higher in older than very young patients for both PR (25.0% vs. 0%, P = 0.018) and PE (44.4% vs. 0%, P = 0.003) groups. In contrast, fibrous cap thickness was greater in very young than older patients for both PR (105.71 ± 48.02 vs. 58.00 ± 15.76 µm, P < 0.001) and PE (126.67 ± 48.22 vs. 54.38 ± 24.21 µm, P < 0.001) groups. Intimal thickness was greater in older than very young patients for both PR (728.00 ± 313.92 vs. 342.27 ± 142.02 µm, P < 0.001) and PE (672.78 ± 334.57 vs. 295.00 ± 99.60 µm, P < 0.001) groups. Conclusion: Frequency of TCFA, microchannels, macrophages, and intimal thickness was significantly higher in older ACS patients compared with very young patients. However, fibrous cap thickness was significantly greater in very young ACS patients compared with older patients.

Selective Use of CT Fractional Flow at a Large Academic Medical Center: Insights from Clinical Implementation after 1 Year of Practice.

Purpose This special report outlines a retrospective observational study of CT fractional flow reserve (CT-FFR) analysis using dual-source coronary CT angiography (CTA) scans performed without heart rate control and its impact on clinical outcomes. Materials and Methods All patients who underwent clinically indicated coronary CTA between August 2020 and August 2021 were included in this retrospective observational study. Scans were performed in the late systolic to early diastolic period without heart rate control and analyzed at the interpreting physician's discretion. Demographics, coronary CTA features, and rates of invasive coronary angiography (ICA), percutaneous coronary intervention (PCI), myocardial infarction, and all-cause death at 3 months were assessed by chart review. Results During the study period, 3098 patients underwent coronary CTA, of whom 113 with coronary bypass grafting were excluded. Of the remaining 2985 patients, 292 (9.7%) were referred for CT-FFR analysis. Two studies (0.7%) were rejected from CT-FFR analysis, and six (2.1%) analyses did not evaluate the lesion of concern. A total of 160 patients (56.3%) had CT-FFR greater than 0.80. Among patients with significant stenosis at coronary CTA, patients who underwent CT-FFR analysis presented with lower rates of ICA (74.5% vs 25.5%, P = .04) and PCI (78.9% vs 21.1%, P = .05). Conclusion CT-FFR was implemented in patients not requiring heart rate control by using dual-source coronary CTA acquisition and showed the potential to decrease rates of ICA and PCI without compromising safety in patients with significant stenosis and an average heart rate of 65 beats per minute. Keywords: Angiography, CT, CT-Angiography, Fractional Flow Reserve, Cardiac, Heart, Arteriosclerosis Supplemental material is available for this article. © RSNA, 2024.

MRI-Based Tumor Necrosis Depiction in Pancreatic Ductal Adenocarcinoma: Can It Predict Tumor Aggressiveness?

The purpose of this study was to investigate whether tumor necrosis depicted on contrast-enhanced abdominal MRI can predict tumor aggressiveness in pancreatic ductal adenocarcinoma (PDAC). In this retrospective analysis, we included 71 patients with pathology-proven PDAC who underwent contrast-enhanced MRI from 2006 to 2020. Assessment for the presence/absence of imaging detected necrosis was performed on T2-weighted and contrast-enhanced T1-weighted images. Primary tumor characteristics, regional lymphadenopathy, metastases, stage, and overall survival were analyzed. Fisher's exact and Mann-Whitney U tests were used for statistical analysis. Of the 72 primary tumors, necrosis was identified on MRI in 58.3% (42/72). Necrotic PDACs were larger (44.6 vs. 34.5 mm, p = 0.0016), had higher rates of regional lymphadenopathy (69.0% vs. 26.7%, p = 0.0007), and more frequent metastases (78.6% vs. 40.0%, p = 0.0010) than those without MRI-evident necrosis. A non-statistically significant reduction in median overall survival was observed in patients with versus without MRI-evident necrosis (15.8 vs. 38.0 months, p = 0.23). PDAC tumor necrosis depicted on MRI was associated with larger tumors and higher frequency of regional lymphadenopathy and metastases.

Abnormal Mechanics Relate to Myocardial Fibrosis and Ventricular Arrhythmias in Patients With Mitral Valve Prolapse.

BACKGROUND: The relation between ventricular arrhythmia and fibrosis in mitral valve prolapse (MVP) is reported, but underlying valve-induced mechanisms remain unknown. We evaluated the association between abnormal MVP-related mechanics and myocardial fibrosis, and their association with arrhythmia. METHODS: We studied 113 patients with MVP with both echocardiogram and gadolinium cardiac magnetic resonance imaging for myocardial fibrosis. Two-dimensional and speckle-tracking echocardiography evaluated mitral regurgitation, superior leaflet and papillary muscle displacement with associated exaggerated basal myocardial systolic curling, and myocardial longitudinal strain. Follow-up assessed arrhythmic events (nonsustained or sustained ventricular tachycardia or ventricular fibrillation). RESULTS: Myocardial fibrosis was observed in 43 patients with MVP, predominantly in the basal-midventricular inferior-lateral wall and papillary muscles. Patients with MVP with fibrosis had greater mitral regurgitation, prolapse, and superior papillary muscle displacement with basal curling and more impaired inferior-posterior basal strain than those without fibrosis (P<0.001). An abnormal strain pattern with distinct peaks pre-end-systole and post-end-systole in inferior-lateral wall was frequent in patients with fibrosis (81 versus 26%, P<0.001) but absent in patients without MVP with basal inferior-lateral wall fibrosis (n=20). During median follow-up of 1008 days, 36 of 87 patients with MVP with >6-month follow-up developed ventricular arrhythmias associated (univariable) with fibrosis, greater prolapse, mitral annular disjunction, and double-peak strain. In multivariable analysis, double-peak strain showed incremental risk of arrhythmia over fibrosis. CONCLUSIONS: Basal inferior-posterior myocardial fibrosis in MVP is associated with abnormal MVP-related myocardial mechanics, which are potentially associated with ventricular arrhythmia. These associations suggest pathophysiological links between MVP-related mechanical abnormalities and myocardial fibrosis, which also may relate to ventricular arrhythmia and offer potential imaging markers of increased arrhythmic risk.

Virtual Unenhanced Images: Qualitative and Quantitative Comparison Between Different Dual-Energy CT Scanners in a Patient and Phantom Study.

MATERIALS AND METHODS: Forty-four patients with clinical contrast-enhanced abdominal examinations on each of the 3 DECT scanner types and a phantom scanned with the same protocols were included in this retrospective study. Qualitative and quantitative assessment was performed on VUE images. Quantitative evaluation included measurement of attenuation and image noise for various tissues and the phantom. Virtual unenhanced image attenuation and noise were compared between scanner types, and intrapatient interscanner reproducibility of virtual unenhanced image attenuation was calculated as the percentage of measurement pairs with an interscanner difference ≤ 10 HU. Image quality, noise, sharpness, and iodine elimination were assessed qualitatively by 2 radiologists. RESULTS: Significant interscanner differences in VUE attenuation and noise were found in all tissues. dlDECT and rsDECT showed significantly higher VUE attenuation than dsDECT in the aorta, portal vein, and kidneys (P < 0.05). Conversely, VUE attenuation in dsDECT was significantly higher than in dlDECT/rsDECT for subcutaneous and retroperitoneal fat (both P < 0.05). A total of 91.9% (385/419) of measurements were reproducible between rsDECT and dlDECT, 70.9% (297/419) between dsDECT and rsDECT, and 66.8% (280/419) between dsDECT and dlDECT. Virtual unenhanced image attenuation in the contrast media-filled phantom cavity was 12.7 ± 4.7 HU in dlDECT, -5.3 ± 4.2 HU in rsDECT, and -4.0 ± 10.7 HU in dsDECT with significant differences between dlDECT and rsDECT/dsDECT, respectively (P < 0.05), between which attenuation was comparable in the unenhanced extraluminal phantom component (P = 0.11-0.62). Qualitatively, dsDECT yielded best iodine elimination, whereas sharpness, image noise, and overall image quality were rated higher in dlDECT and rsDECT. CONCLUSIONS: There are significant interscanner differences in the attenuation measurements and qualitative assessment of VUE images, which should be acknowledged when using these images in patients that are being scanned on different DECT scanner types during imaging follow-up.