Impact of radiological and pathological splenic vein involvement in patients with resectable pancreatic body or tail cancer.

PURPOSE: Several studies have reported a negative impact on survival associated with splenic vessel involvement, especially splenic artery (SpA) involvement, in patients diagnosed with pancreatic body or tail cancer. However, there is limited research on splenic vein (SpV) involvement. Therefore, we aimed to elucidate the significance of splenic vessel involvement, especially SpV involvement, in patients with resectable pancreatic body or tail cancer. METHODS: Between January 2007 and December 2021, 116 consecutive patients underwent distal pancreatectomies for pancreatic body or tail cancer. Among them, this study specifically examined 88 patients with resectable pancreatic body or tail cancer to elucidate prognostic factors using a multivariable Cox proportional analysis. The Kaplan-Meier method evaluated the impact of SpV involvement in terms of both radiological and pathological aspects and the efficacy of neoadjuvant therapy. RESULTS: Higher pre-operative carcinoembryonic antigen levels, larger tumour size, pathological SpV invasion, and non-completion of adjuvant therapy were identified as independent poor prognostic factors for overall survival (OS) and recurrence-free survival (RFS). Additionally, patients with radiological SpV encasement had significantly worse prognoses in terms of OS (p = 0.039) and RFS (p < 0.001). The sensitivity and specificity of multidetector-row computed tomography for detecting pathological SpV invasion were 81.0% and 61.2%, respectively. However, the prognostic impact of neoadjuvant therapy could not be determined, regardless of radiological SpV involvement. CONCLUSION: Radiological and pathological SpV involvement is a poor prognostic factor for patients with resectable pancreatic body or tail cancer. New innovative treatments and effective neoadjuvant therapy regimens are required for patients with SpV involvement.

Choledochocele with hyperplastic epithelium in a patient who developed severe acute pancreatitis and underwent subtotal stomach-preserving pancreatoduodenectomy: a case report.

Choledochocele is defined as a congenital dilatation of the distal intramural part of the common bile duct protruding into the wall of the descending duodenum, typically without pancreaticobiliary maljunction. However, some cases present with a similar pathophysiology to pancreaticobiliary maljunction, including reciprocal reflux of pancreatic juices and bile, leading to protein plugs, pancreatitis, and biliary tract carcinogenesis. Choledochocele is relatively rare and its anatomy, physiology, pathology, and clinical features are thus not well known. We describe a patient with choledochocele who suffered from repeated severe acute pancreatitis and underwent subtotal stomach-preserving pancreatoduodenectomy, in whom the pathological findings of choledochocele showed hyperplasia.

Mixed epithelial and stromal tumor of the kidney with long-term imaging follow-up.

Mixed epithelial and stromal tumor (MEST) of the kidney is a rare benign tumor with malignant potential, and is characterized by epithelial and stromal proliferation with a variety of cellularity and growth pattern. MEST of the kidney is often depicted as a well-defined, solid mass with a cystic component. However, due to the rarity of the disease, there are no reports of its progression in serial imaging examinations. This report presents the case of a 68-year-old woman with MEST who was followed for 13 years by computed tomography (CT). To the best of our knowledge, this is the first report of image findings of MEST of the kidney over a follow-up period longer than 10 years.

Extrapancreatic extension is a better adverse prognostic factor than tumor size in patients with localized pancreatic ductal adenocarcinoma treated with chemoradiotherapy - comparison of T category between the American Joint Committee on Cancer and Japan Pancreas Society.

BACKGROUND: T category classification for pancreatic ductal adenocarcinoma (PDAC) in the Classification of Pancreatic Cancer by the Japan Pancreas Society (JPS) is quite different from that of the American Joint Committee on Cancer (AJCC). The JPS classification focuses on extrapancreatic extension, while the AJCC focuses mainly on tumor size. This study aimed at identifying prognostic factors in PDAC patients undergoing chemoradiotherapy (CRT) by comparing the differences of T categories in these two classifications. METHODS: This retrospective study involved 344 PDAC patients who underwent CRT from 2005 to 2019 and their T-category variables were re-evaluated on computed tomography (CT) images. Disease-specific survival (DSS) was compared based on the JPS and AJCC T categories, while multivariate analysis was performed to identify prognostic factors. RESULTS: Based on the AJCC, 5-year DSS of T3 was better than those of T1 and T2 (57.1% vs. 47.7% and 37.4%). In multivariate analysis, performance status, CEA, the involvement of superior mesenteric vein and superior mesenteric artery, the JPS stage before CRT, and regimen of chemotherapy were identified as independent prognostic factors. CONCLUSIONS: In localized PDAC patients treated with chemoradiotherapy, extrapancreatic extension, as while as biological, conditional and therapeutic factors, is a better prognostic factor than tumor size.

Anterior versus posterior radical antegrade modular pancreatosplenectomy for pancreatic body and tail cancer: an inverse probability of treatment weighting with survival analysis.

PURPOSE: Radical antegrade modular pancreatosplenectomy (RAMPS) is a standard procedure for patients with pancreatic body and tail cancer. There are two types of RAMPS: anterior and posterior, but their indications and surgical outcomes remain unclear. We compared the surgical outcomes, postoperative course, and prognosis between anterior and posterior RAMPS. METHODS: Between 2007 and 2020, 105 consecutive patients who underwent RAMPS for pancreatic body and tail cancers were divided into an anterior RAMPS group (n = 30) and a posterior RAMPS group (n = 75). To adjust for differences in preoperative characteristics and intraoperative procedures, an inverse probability of treatment weighting (IPTW) analysis was done, using propensity scores. RESULTS: After IPTW adjustment, the postoperative body temperature of the posterior RAMPS group and the amount of drain discharge in the anterior RAMPS group were significantly lower, from postoperative days (PODs) 1 to 3, but there were no differences in postoperative complications, recurrence patterns, or prognosis between the two groups. Regarding the diagnostic ability of multidetector-row computed tomography (MD-CT) for direct tumor involvement of the left adrenal gland, the sensitivity and specificity were 100% and 90.0%, respectively. CONCLUSION: Pancreatic body and tail cancer without apparent preoperative direct tumor involvement of the left adrenal gland on MD-CT may be sufficient indication for anterior RAMPS.

Application of Deep Learning-Based Denoising Technique for Radiation Dose Reduction in Dynamic Abdominal CT: Comparison with Standard-Dose CT Using Hybrid Iterative Reconstruction Method.

The purpose is to evaluate whether deep learning-based denoising (DLD) algorithm provides sufficient image quality for abdominal computed tomography (CT) with a 30% reduction in radiation dose, compared to standard-dose CT reconstructed with conventional hybrid iterative reconstruction (IR). The subjects consisted of 50 patients who underwent abdominal CT with standard dose and reconstructed with hybrid IR (ASiR-V50%) and another 50 patients who underwent abdominal CT with approximately 30% less dose and reconstructed with ASiR-V50% and DLD at low-, medium- and high-strength (DLD-L, DLD-M and DLD-H, respectively). The standard deviation of attenuation in liver parenchyma was measured as image noise. Contrast-to-noise ratio (CNR) for portal vein on portal venous phase was calculated. Lesion conspicuity in 23 abdominal solid mass on the reduced-dose CT was rated on a 5-point scale: 0 (best) to -4 (markedly inferior). Compared with hybrid IR of standard-dose CT, DLD-H of reduced-dose CT provided significantly lower image noise (portal phase: 9.0 (interquartile range, 8.7-9.4) HU vs 12.0 (11.4-12.7) HU, P < 0.0001) and significantly higher CNR (median, 5.8 (4.4-7.4) vs 4.3 (3.3-5.3), P = 0.0019). As for DLD-M of reduced-dose CT, no significant difference was found in image noise and CNR compared to hybrid IR of standard-dose CT (P > 0.99). Lesion conspicuity scores for DLD-H and DLD-M were significantly better than hybrid IR (P < 0.05). Dynamic contrast-enhanced abdominal CT acquired with approximately 30% lower radiation dose and generated with the DLD algorithm exhibit lower image noise and higher CNR compared to standard-dose CT with hybrid IR.

Concomitant splenic artery ligation has no preventive effect on left-sided portal hypertension following pancreaticoduodenectomy with the resection of the portal and superior mesenteric vein confluence for pancreatic ductal adenocarcinoma.

Background: Left-sided portal hypertension (LSPH) caused by splenic vein (SV) division in pancreaticoduodenectomy (PD) with portal vein (PV) resection remains challenging. The current study aimed to investigate the efficacy of splenic artery (SA) ligation in preventing LSPH. Methods: One-hundred thirty patients who underwent PD with PV resection for pancreatic ductal adenocarcinoma were classified into SV and SA preservation (SVP, n = 30), SV resection and SA preservation (SVR, n = 59), and SV resection and SA ligation (SAL, n = 41). The postoperative incidence of LSPH was assessed. Results: The incidence of variceal formation in SVP, SVR, and SAL were 4.8%, 53.2%, and 46.4% at 3 mo, 13.0%, 71.2%, and 62.5% at 6 mo, and 25.0%, 87.5%, and 87.1% at 12 mo, respectively. The rate was significantly higher in SVR at 3 and 6 mo (P = .001 and P < .001, respectively) and in SVR and SAL (P < .001) at 12 mo. Variceal hemorrhage occurred only in SVR (n = 4). The platelet count ratio at 3, 6, and 12 mo began to significantly decrease from 3 mo in SVR (0.77, 0.67, and 0.60, respectively; P < .001) and 6 mo in SAL (0.91, 0.73, and 0.69, respectively; P < .001). The spleen volume ratio also showed significant increase from 3 mo in SVR (1.24, 1.34, and 1.42, respectively; P < .001) and 6 mo in SAL (1.31, 1.32, and 1.34, respectively; P < .001). SVR and SAL were significant risk factors for variceal formation at 12 mo (odds ratio, 21.0 and 20.3, respectively). Conclusion: In PD with PV resection, SAL delayed LSPH but could not prevent its occurrence.

Deep learning image reconstruction for improving image quality of contrast-enhanced dual-energy CT in abdomen.

OBJECTIVES: To evaluate the usefulness of deep learning image reconstruction (DLIR) to improve the image quality of dual-energy computed tomography (DECT) of the abdomen, compared to hybrid iterative reconstruction (IR). METHODS: This study included 40 patients who underwent contrast-enhanced DECT of the abdomen. Virtual monochromatic 40-, 50-, and 70-keV and iodine density images were reconstructed using three reconstruction algorithms, including hybrid IR (ASiR-V50%) and DLIR (TrueFidelity) at medium- and high-strength level (DLIR-M and DLIR-H, respectively). The standard deviation of attenuation in liver parenchyma was measured as image noise. The contrast-to-noise ratio (CNR) for the portal vein on portal venous phase CT was calculated. The vessel conspicuity and overall image quality were graded on a 5-point scale ranging from 1 (poor) to 5 (excellent). The comparative scale of lesion conspicuity in 47 abdominal solid lesions was evaluated on a 5-point scale ranging from 0 (best) to -4 (markedly inferior). RESULTS: The image noise of virtual monochromatic 40-, 50 -, and 70-keV and iodine density images was significantly decreased by DLIR compared to hybrid IR (p < 0.0001). The CNR was significantly higher in DLIR-H and DLIR-M than in hybrid IR (p < 0.0001). The vessel conspicuity and overall image quality scores were also significantly greater in DLIR-H and DLIR-M than in hybrid IR (p < 0.05). The lesion conspicuity scores for DLIR-M and DLIR-H were significantly higher than those for hybrid IR in the virtual monochromatic image of all energy levels (p ≤ 0.001). CONCLUSIONS: DLIR improves vessel conspicuity, CNR, and lesion conspicuity of virtual monochromatic and iodine density images in abdominal contrast-enhanced DECT, compared to hybrid IR. KEY POINTS: • Deep learning image reconstruction (DLIR) is useful for reducing image noise and improving the CNR of visual monochromatic 40-, 50-, and 70-keV images in dual-energy CT. • DLIR can improve lesion conspicuity of abdominal solid lesions on virtual monochromatic images compared to hybrid iterative reconstruction. • DLIR can also be applied to iodine density maps and significantly improves their image quality.

Deep learning image reconstruction for improvement of image quality of abdominal computed tomography: comparison with hybrid iterative reconstruction.

PURPOSE: To evaluate the usefulness of the deep learning image reconstruction (DLIR) to enhance the image quality of abdominal CT, compared to iterative reconstruction technique. METHOD: Pre and post-contrast abdominal CT images in 50 patients were reconstructed with 2 different algorithms: hybrid iterative reconstruction (hybrid IR: ASiR-V 50%) and DLIR (TrueFidelity). Standard deviation of attenuation in normal liver parenchyma was measured as the image noise on pre and post-contrast CT. The contrast-to-noise ratio (CNR) for the aorta, and the signal-to-noise ratio (SNR) of the liver were calculated on post-contrast CT. The overall image quality was graded on a 5-point scale ranging from 1 (poor) to 5 (excellent). RESULTS: The image noise was significantly decreased by DLIR compared to hybrid-IR [hybrid IR, median 8.3 Hounsfield unit (HU) (interquartile range (IQR) 7.6-9.2 HU); DLIR, median 5.2 HU (IQR 4.6-5.8), P < 0.0001 for post-contrast CT]. The CNR and SNR were significantly improved by DLIR [CNR, median 4.5 (IQR 3.8-5.6) vs 7.3 (IQR 6.2-8.8), P < 0.0001; SNR, median 9.4 (IQR 8.3-10.1) vs 15.0 (IQR 13.2-16.4), P < 0.0001]. The overall image quality score was also higher for DLIR compared to hybrid-IR (hybrid IR 3.1 ± 0.6 vs DLIR 4.6 ± 0.5, P < 0.0001 for post-contrast CT). CONCLUSIONS: Image noise, overall image quality, CNR and SNR for abdominal CT images are improved with DLIR compared to hybrid IR.

Usefulness of dictionary learning-based processing for improving image quality of sub-millisievert low-dose chest CT: initial experience.

PURPOSE: To develop a dictionary learning (DL)-based processing technique for improving the image quality of sub-millisievert chest computed tomography (CT). MATERIALS AND METHODS: Standard-dose and sub-millisievert chest CT were acquired in 12 patients. Dictionaries including standard- and low-dose image patches were generated from the CT datasets. For each patient, DL-based processing was performed for low-dose CT using the dictionaries generated from the remaining 11 patients. This procedure was repeated for all 12 patients. Image quality of normal thoracic structures on the processed sub-millisievert CT images was assessed with a 5-point scale (5 = excellent, 1 = very poor). Lung lesion conspicuity was also assessed on a 5-point scale. RESULTS: Image noise on sub-millisievert CT was significantly decreased with DL-based image processing (48.5 ± 13.7 HU vs 20.4 ± 7.9 HU, p = 0.0005). Image quality of lung structures was significantly improved with DL-based method (middle level of lung, 2.25 ± 0.75 vs 2.92 ± 0.79, p = 0.0078). Lung lesion conspicuity was also significantly improved with DL-based technique (solid nodules, 3.4 ± 0.6 vs 2.7 ± 0.6, p = 0.0273). CONCLUSION: Image quality and lesion conspicuity on sub-millisievert chest CT images may be improved by DL-based post-processing.

Perfusion CT to Assess Response to Neoadjuvant Chemotherapy and Radiation Therapy in Pancreatic Ductal Adenocarcinoma: Initial Experience.

BackgroundChange in tumor size at CT is insufficient for reliable assessment of treatment response after neoadjuvant chemotherapy and radiation therapy (CRT) and shows poor correlation with histologic grading of response.PurposeTo investigate the use of perfusion CT to predict the response of pancreatic ductal adenocarcinoma (PDA) to CRT.Materials and MethodsBetween June 2016 and May 2018, study participants with biopsy-proven PDA were prospectively recruited to undergo perfusion CT before and after planned CRT. Blood flow (BF), blood volume (BV), and permeability-surface area product (PSP) were quantified from CT images. Participants were categorized into responders and nonresponders according to therapy response. The Mann-Whitney test was used to compare the baseline perfusion values between responders and nonresponders, and the Wilcoxon matched-pairs signed rank test was used to compare perfusion values before and after CRT.ResultsThe final cohort of 21 participants (median age, 68 years; interquartile range [IQR], 65-72 years; eight men) underwent dynamic perfusion (dual-source) CT before neoadjuvant CRT. All participants underwent pancreatectomy. Eighteen participants underwent post-CRT perfusion CT. Baseline BF was higher in responders (n = 10) than in nonresponders (n = 11) (median, 44 [IQR, 39-56] vs 28 [IQR, 16-52] mL/100 g/min; P = .04), while BV and PSP were similar between groups (median BV, 4.3 [IQR, 3.5-6.9] vs 2.0 [IQR, 1.6-6.5] mL/100 g, P = .15; median PSP, 25 [IQR, 21-30] vs 20 [IQR, 10-34] mL/100 g/min, P = .31). Response Evaluation Criteria in Solid Tumors (RECIST) and carbohydrate antigen (CA) 19-9 showed no correlation with perfusion parameters (eg, RECIST and BF: r = 0.05, P = .84, 95% confidence interval [CI]: -0.40, 0.48; CA 19-9 and BF: r = 0.06, P = .78, 95% CI: -0.39, 0.49) or histopathologic response (r = 0.16, P = .47, 95% CI: -0.3, 0.57 and r = 0.09, P = .71, 95% CI: -0.37, 0.51, respectively). For responders, perfusion parameters increased after CRT (eg, median BF, 54 [IQR, 42-73] vs 43 [IQR, 28-53] mL/100 g/min; P = .04). The perfusion change in nonresponders was not significant (median BF, 43 [IQR, 28-53] vs 33 [IQR, 16-52] mL/100 g/min; P = .06).ConclusionPerfusion CT may be useful in helping predict the histopathologic response to therapy in pancreatic ductal adenocarcinoma.© RSNA, 2019See also the editorial by Sinitsyn in this issue.

Combined Assessment of Stress Myocardial Perfusion Cardiovascular Magnetic Resonance and Flow Measurement in the Coronary Sinus Improves Prediction of Functionally Significant Coronary Stenosis Determined by Fractional Flow Reserve in Multivessel Disease.

BACKGROUND: Recent studies using stress-rest perfusion cardiovascular magnetic resonance (CMR) demonstrated a close correlation between myocardial ischemia and reduced fractional flow reserve (FFR). However, its diagnostic concordance may be reduced in patients with multivessel disease. We sought to evaluate the concordance of adenosine stress-rest perfusion CMR for predicting reduced FFR, and to determine the additive value of measuring global coronary flow reserve (CFR) in the coronary sinus in multivessel disease. METHODS AND RESULTS: Ninety-six patients with angiographic luminal narrowing >50% underwent comprehensive CMR study and FFR measurements in 139 coronary vessels. FFR <0.80 was considered hemodynamically significant. Global CFR was quantified as the ratio of stress-rest coronary sinus flow measured by phase-contrast cine CMR. In 25 patients with single-vessel disease, visual assessment of perfusion CMR yielded high diagnostic concordance for predicting flow-limiting stenosis, with the area under receiver operating characteristic curve of 0.93 on a per-patient basis. However, in 71 patients with multivessel disease, perfusion CMR underestimated flow-limiting stenosis, resulting in the reduced area under receiver operating characteristic curve of 0.74. When CFR of <2.0 measured in the coronary sinus was considered as global myocardial ischemia, combined assessment provided correct reclassifications in 7 patients with false-negative myocardial ischemia, and improved the diagnostic concordance to 92% sensitivity and 73% specificity with the area under receiver operating characteristic curve of 0.88 (95% confidence interval, 0.80%-0.97%, P=0.002). CONCLUSIONS: Visual analysis of stress-rest perfusion CMR has limited concordance with FFR in patients with multivessel disease. Multiparametric CMR integrating stress-rest perfusion CMR and flow measurement in the coronary sinus is useful for detecting reduced FFR in multivessel disease.

Significance of Simultaneous Splenic Artery Resection in Left-Sided Portal Hypertension After Pancreaticoduodenectomy with Combined Portal Vein Resection.

BACKGROUND: In pancreaticoduodenectomy (PD) with resection of portal vein (PV)/superior mesenteric vein (SMV) confluence, the splenic vein (SV) division may cause left-sided portal hypertension (LPH). METHODS: The 88 pancreatic ductal adenocarcinoma patients who underwent PD with PV/SMV resection after chemoradiotherapy were classified into three groups: both SV and splenic artery (SA) were preserved in Group A (n = 16), SV was divided and SA was preserved in Group B (n = 58), and both SV and SA were divided in Group C (n = 14). We evaluated the influence of resection of SV and/or SA on LPH after PD with resection of PV/SMV confluence. RESULTS: The incidence of postoperative varices in Groups A, B and C was 6.3, 67.2 and 38.5%, respectively (p < 0.001), and variceal bleeding occurred only in Group B (n = 4: 6.8%). In multivariate analysis, Group B was the only significant risk factor for the development of postoperative varices (Groups B vs. A: odds ratio = 39.6, p = 0.001, Groups C vs. A: odds ratio = 8.75, p = 0.066). The platelet count ratio at 6 months after operation comparing to preoperative value was 0.93, 0.73 and 1.09 in Groups A, B and C, respectively (Groups B vs. C: p < 0.05), and spleen volume ratio at 6 months was 1.00, 1.37 and 0.96 in Groups A, B and C, respectively (Groups B vs. A and C: p < 0.01 and p < 0.05). CONCLUSION: In PD with resection of PV-SMV confluence, the SV division causes LPH, but the concomitant division of SV and SA may attenuate it.

Comparison of Displacement Encoding With Stimulated Echoes to Magnetic Resonance Feature Tracking for the Assessment of Myocardial Strain in Patients With Acute Myocardial Infarction.

The aim of this study was to compare myocardial strain by cardiovascular magnetic resonance feature tracking (CMR-FT) to those derived from displacement encoding with stimulated echoes (DENSE) in patients with acute myocardial infarction (AMI). Twenty patients (65 pa13 years) with AMI underwent cine, DENSE, black-blood T2-weighted and late gadolinium enhancement CMR at 1.5 T. Global and segmental strain was determined by CMR-FT analysis and DENSE on matched 3 short-axis planes. Global circumferential strain by CMR-FT showed a good agreement with that by DENSE (r = 0.85, p <0.001; bias 0.02, limits of agreement -0.03 to 0.06). For segmental circumferential strain, r coefficient between CMR-FT and DENSE was 0.61 (p <0.001) with bias of 0.02, limits of agreement of -0.07 to 0.11. Regional circumferential strain determined by CMR-FT in infarct segments (-0.08 ± 0.05) was significantly altered compared with that in remote normal segments (-0.15 ± 0.05, p <0.001). CMR-FT measurement of regional and global circumferential strain showed good agreement with DENSE in patients with AMI.

Underestimation of myocardial blood flow by dynamic perfusion CT: Explanations by two-compartment model analysis and limited temporal sampling of dynamic CT.

PURPOSE: Previous studies using dynamic perfusion CT and volume perfusion CT (VPCT) software consistently underestimated the stress myocardial blood flow (MBF) in normal myocardium to be 1.1-1.4 ml/min/g, whilst the O 15-water PET studies demonstrated the normal stress MBF of 3-5 ml/min/g. We hypothesized that the MBF determined by VPCT (MBF-VPCT) is actually presenting the blood-to-myocardium transfer constant, K1. In this study, we determined K1 using Patlak plot (K1-Patlak) and compared the results with MBF-VPCT. MATERIAL AND METHODS: 17 patients (66 ± 9 years, 7 males) with suspected coronary artery disease (CAD) underwent stress dynamic perfusion CT, followed by rest coronary CT angiography (CTA). Arterial input and myocardial output curves were analyzed with Patlak plot to quantify myocardial K1. Significant CAD was defined as >50% stenosis on CTA. A simulation study was also performed to investigate the influence of limited temporal sampling in dynamic CT acquisition on K1 using the undersampling data generated from MRI. RESULTS: There were 3 patients with normal CTA, 7 patients with non-significant CAD, and 7 patients with significant CAD. K1-patlak was 0.98 ± 0.35 (range 0.22-1.67) ml/min/g, whereas MBF-VPCT was 0.83 ± 0.23 (range 0.34-1.40) ml/min/g. There was a linear relationship between them: (MBF-VPCT) = 0.58 x (K1-patlak) + 0.27 (r(2) = 0.65, p < 0.001). The simulation study done on MRI data demonstrated that Patlak plot substantially underestimated true K1 by 41% when true K1 was 2.0 ml/min/g with the temporal sampling of 2RR for arterial input and 4RR for myocardial output functions. CONCLUSIONS: The results of our study are generating hypothesis that MBF-VPCT is likely to be calculating K1-patlak equivalent, not MBF. In addition, these values may be substantially underestimated because of limited temporal sampling rate.

Theoretical considerations in measurement of time discrepancies between input and myocardial time-signal intensity curves in estimates of regional myocardial perfusion with first-pass contrast-enhanced MRI.

The purpose of this study was to develop a method to determine time discrepancies between input and myocardial time-signal intensity (TSI) curves for accurate estimation of myocardial perfusion with first-pass contrast-enhanced MRI. Estimation of myocardial perfusion with contrast-enhanced MRI using kinetic models requires faithful recording of contrast content in the blood and myocardium. Typically, the arterial input function (AIF) is obtained by setting a region of interest in the left ventricular cavity. However, there is a small delay between the AIF and the myocardial curves, and such time discrepancies can lead to errors in flow estimation using Patlak plot analysis. In this study, the time discrepancies between the arterial TSI curve and the myocardial tissue TSI curve were estimated based on the compartment model. In the early phase after the arrival of the contrast agent in the myocardium, the relationship between rate constant K1 and the concentrations of Gd-DTPA contrast agent in the myocardium and arterial blood (LV blood) can be described by the equation K1={dCmyo(tpeak)/dt}/Ca(tpeak), where Cmyo(t) and Ca(t) are the relative concentrations of Gd-DTPA contrast agent in the myocardium and in the LV blood, respectively, and tpeak is the time corresponding to the peak of Ca(t). In the ideal case, the time corresponding to the maximum upslope of Cmyo(t), tmax, is equal to tpeak. In practice, however, there is a small difference in the arrival times of the contrast agent into the LV and into the myocardium. This difference was estimated to correspond to the difference between tpeak and tmax. The magnitudes of such time discrepancies and the effectiveness of the correction for these time discrepancies were measured in 18 subjects who underwent myocardial perfusion MRI under rest and stress conditions. The effects of the time discrepancies could be corrected effectively in the myocardial perfusion estimates.

Myocardial delayed enhancement with dual-source CT: advantages of targeted spatial frequency filtration and image averaging over half-scan reconstruction.

BACKGROUND: Clinical utility of myocardial delayed-enhancement CT is currently limited because of relatively poor contrast-to-noise ratio (CNR) and artifacts. Targeted spatial-frequency filtration (TSFF) is a hybrid algorithm of half- and full-scan reconstruction that can achieve both high temporal resolution and improved stability of myocardial signal. OBJECTIVE: The purpose of this study was to evaluate image quality of delayed-enhancement CT using TSFF with image averaging and its reproducibility in infarct assessment in comparison with conventional half-scan reconstruction (HALF). METHODS: Forty patients with suspected coronary artery disease underwent delayed-enhancement CT with HALF and TSFF using dual-source CT. Two blinded readers independently determined the presence and size of delayed enhancement. Image quality, signal-to-noise ratio and CNR were assessed. The presence of delayed enhancement on CT was compared with magnetic resonance imaging in 12 patients. RESULTS: TSFF with averaging of 4 image stacks acquired during 1 breathhold demonstrated significantly better image quality compared with HALF. Good left ventricular lumen-myocardium contrast was consistently achieved with TSFF in patients who received iodine dose of >600 mg I/kg. The signal-to-noise ratio and CNR were 11.3 ± 4.2 and 4.5 ± 1.6 by TSFF, being significantly higher than those by HALF (7.9 ± 2.9 and 3.3 ± 1.8; P < .01 for both). Interobserver reproducibility of infarct sizing was markedly improved by using TSFF instead of HALF (intraclass correlation coefficient: 0.86 vs 0.50). Agreement with magnetic resonance imaging by kappa statistics was 0.85 with TSFF and 0.74 with HALF. CONCLUSIONS: TSFF with image averaging can significantly improve image quality of delayed-enhancement CT and considerably enhances interobserver reproducibility of infarct sizing.

Detection of diminished response to cold pressor test in smokers: assessment using phase-contrast cine magnetic resonance imaging of the coronary sinus.

PURPOSE: The purposes of this study were to evaluate the reproducibility for measuring the cold pressor test (CPT)-induced myocardial blood flow (MBF) alteration using phase-contrast (PC) cine MRI, and to determine if this approach could detect altered MBF response to CPT in smokers. MATERIALS AND METHODS: After obtaining informed consent, ten healthy male non-smokers (mean age: 28±5 years) and ten age-matched male smokers (smoking duration ≥5 years, mean age: 28±3 years) were examined in this institutional review board approved study. Breath-hold PC cine MR images of the coronary sinus were obtained with a 3T MR imager with 32 channel coils at rest and during a CPT performed after immersing one foot in ice water. MBF was calculated as coronary sinus flow divided by the left ventricular (LV) mass which was given as a total LV myocardial volume measured on cine MRI multiplied by the specific gravity (1.05 g/mL). RESULTS: In non-smokers, MBF was 0.86±0.25 mL/min/g at rest, with a significant increase to 1.20±0.36 mL/min/g seen during CPT (percentage change of MBF (∆MBF (%)); 39.2%±14.4%, p<0.001). Inter-study reproducibility for ∆MBF (%) measurements by different MR technologist was good, as indicated by the intraclass correlation coefficient of 0.93 and reproducibility coefficient of 10.5%. There was no significant difference between smokers and non-smokers for resting MBF (0.85±0.32 mL/min/g, p=0.91). However, ∆MBF (%) in smokers was significantly reduced (-4.0±32.2% vs. 39.2±14.4%, p=0.011). CONCLUSION: PC cine MRI can be used to reproducibly quantify MBF response to CPT and to detect impaired flow response in smokers. This MR approach may be useful for monitoring the sequential change of coronary blood flow in various potentially pathologic conditions and for investigating its relationship with cardiovascular risk.

Quantitative analysis of 1.5-T whole-heart coronary MR angiograms obtained with 32-channel cardiac coils: a comparison with conventional quantitative coronary angiography.

PURPOSE: To develop a method to determine significant stenosis at whole-heart coronary magnetic resonance (MR) angiography and to evaluate the accuracy and reproducibility of this approach. MATERIALS AND METHODS: The institutional review board approved the study, and all participants provided written informed consent. Sixty-two patients who were suspected of having coronary artery disease (CAD) and were scheduled for conventional coronary angiography were included. Coronary MR angiography was performed by using a 1.5-T imager with 32-channel coils. Luminal narrowing was evaluated with quantitative analysis (QA) of coronary MR angiograms on the basis of the signal intensity profile along the vessel. Percentage stenosis with QA of coronary MR angiograms was calculated as [1 - (SI(min)/SI(ref))] × 100, where SI(min) is minimal signal intensity and SI(ref) is corresponding reference signal intensity. Diagnostic performance of QA of coronary MR angiograms for predicting at least a 50% reduction in diameter was evaluated by using quantitative coronary angiography (QCA), with conventional angiography findings serving as the reference standard. Receiver operating characteristic (ROC) analysis, Spearman rank correlation, Bland-Altman analysis, and Cohen κ analysis were used. RESULTS: The areas under the ROC curve in a segment-based analysis for detecting significant CAD were 0.96 (95% confidence interval [CI]: 0.94, 0.98) with QA of coronary MR angiograms and 0.93 (95% CI: 0.88, 0.98) with visual assessment. The correlation coefficients between percentage stenosis with QA of coronary MR angiograms and percentage stenosis with QCA were 0.84 (P < .001), 0.80 (P < .001), and 0.66 (P < .001) in the patient-, vessel-, and segment-based analyses, respectively. CONCLUSION: QA of coronary MR angiograms with use of a signal intensity profile along the vessel permits detection of CAD. This method had a diagnostic performance approximately equal to that of visual analysis of coronary MR angiograms with high inter- and intraobserver reliability, allowing for more objective interpretation of coronary MR angiography findings.

Dose reduction in dynamic CT stress myocardial perfusion imaging: comparison of 80-kV/370-mAs and 100-kV/300-mAs protocols.

OBJECTIVES: To determine the effect of reduced 80-kV tube voltage with increased 370-mAs tube current on radiation dose, image quality and estimated myocardial blood flow (MBF) of dynamic CT stress myocardial perfusion imaging (CTP) in patients with a normal body mass index (BMI) compared with a 100-kV and 300-mAs protocol. METHODS: Thirty patients with a normal BMI (<25 kg/m(2)) with known or suspected coronary artery disease underwent adenosine-stress dual-source dynamic CTP. Patients were randomised to 80-kV/370-mAs (n = 15) or 100-kV/300-mAs (n = 15) imaging. Maximal enhancement and noise of the left ventricular (LV) cavity, contrast-to-noise ratio (CNR) and MBF of the two groups were compared. RESULTS: Imaging with 80-kV/370-mAs instead of 100-kV/300-mAs was associated with 40% lower radiation dose (mean dose-length product, 359 ± 66 vs 628 ± 112 mGy[Symbol: see text]cm; P < 0.001 ) with no significant difference in CNR (34.5 ± 13.4 vs 33.5 ± 10.4; P = 0.81) or MBF in non-ischaemic myocardium (0.95 ± 0.20 vs 0.99 ± 0.25 ml/min/g; P = 0.66). Studies obtained using 80-kV/370-mAs were associated with 30.9% higher maximal enhancement (804 ± 204 vs 614 ± 115 HU; P < 0.005), and 31.2% greater noise (22.7 ± 3.5 vs 17.4 ± 2.6; P < 0.001). CONCLUSIONS: Dynamic CTP using 80-kV/370-mA instead of 100-kV/300-mAs allowed 40% dose reduction without compromising image quality or MBF. Tube voltage of 80-kV should be considered for individuals with a normal BMI. KEY POINTS: • CT stress perfusion imaging (CTP) is increasingly used to assess myocardial function. • Dynamic CTP is feasible at 80-kV in patients with normal BMI. • An 80-kV/370-mAs protocol allows 40% dose reduction compared with 100-kV/300-mAs. • Contrast-to-noise ratio and myocardial blood flow of the two protocols were comparable.