Epicardial adipose tissue density predicts the presence of atrial fibrillation and its recurrence after catheter ablation: three-dimensional reconstructed image analysis.

Epicardial adipose tissue (EAT) induces inflammation in the atria and is associated with atrial fibrillation (AF). Several studies have examined the relationship between EAT volume (EAT-V) and density (EAT-D) and the presence of AF after catheter ablation. However, conclusions have been inconsistent. This study included 43 consecutive patients who underwent catheter ablation for AF and 30 control patients. EAT-V and EAT-D around the entire heart, entire atrium, left atrium (LA), and right atrium (RA) were measured in detail using reconstructed three-dimensional (3D) EAT images from dual-source computed tomography (CT). None of the measurements of EAT-V differed significantly between patients with AF and controls or between patients with recurrent AF and those without. On the other hand, all measurements of EAT-D were higher in patients with AF than in controls (entire atrium, p < 0.001; RA, p < 0.001; LA, p = 0.002). All EAT-D measurements were associated with the presence of AF. Among patients with AF who underwent ablation, all EAT-D measurements were higher in patients with recurrent AF than in those without. The difference was significant for EATRA-D (p = 0.032). All atrial EAT-D values predicted recurrent AF (EATRA-D: hazard ratio [HR], 1.208; 95% confidence interval [95% CI], 1.053-1.387; p = 0.007; EATLA-D: HR, 1.108; 95% CI 1.001-1.225; p = 0.047; EATatrial-D: HR, 1.174; 95% CI 1.040-1.325; p = 0.010). The most sensitive cutoffs for predicting recurrent AF were highly accurate for EATRA-D (area under the curve [AUC], 0.76; p < 0.01) and EATatrial-D (AUC = 0.75, p < 0.05), while the cutoff for EATLA-D had low accuracy (AUC, 0.65; p = 0.209). For predicting the presence of AF and recurrent AF after catheter ablation, 3D analysis of atrial EAT-D, rather than EAT-V, is useful.

Contrast-enhanced computed tomography in the venous rather than the arterial phase is essential for the evaluation of the right phrenic nerve.

BACKGROUND: Preprocedural detection of the running course of the right pericardiophrenic bundles (PBs) is considered to be useful in preventing phrenic nerve (PN) injury during catheter ablation for atrial fibrillation (AF). However, previous studies using the arterial phase of contrast-enhanced computed tomography (CT) reported a relatively low right PBs detection rate. METHODS: This study included 63 patients with AF who underwent catheter ablation and preoperative contrast-enhanced CT imaging of the venous and arterial phases (66.7 ± 10.2 years; 44 male). The venous phase of contrast-enhanced CT significantly improved the detection rate of PBs compared to the arterial phase (96.8% vs. 60.3%, p < .001), and PBs were detected in the venous phase only in 23 (36.7%) patients. No significant differences were observed between the right PBs detection rate using non-contrast CT versus the arterial phase of contrast-enhanced CT (p = .37). Patients without visualization of the right PBs during the arterial phase had a higher frequency of chronic heart failure (p = .0083), lower left ventricular ejection fraction (p = .021), and a higher CHADS2 score (p = .048) than those with visualization. In five patients whose right PBs could only be detected during the venous phase of contrast-enhanced CT, the reconstructed running course of the right PBs corresponded with the PN generated by electrical high-output pacing. CONCLUSION: Contrast-enhanced CT images of the venous phase, rather than the arterial phase, are useful in detecting the right PBs, especially in patients with heart failure or reduced left ventricular ejection fraction.

Phrenic nerve stimulation during right ventricular outflow tract pacing: A rare but possible complication.

Phrenic nerve stimulation (PNS) caused by a right ventricular (RV) lead is an uncommon complication of pacemaker implantations. We demonstrated a case of left PNS caused by an RV lead placed in the RV outflow tract (RVOT). The PNS was dependent on ventricular capture. This case highlighted a risk of PNS even during RVOT pacing.

Usefulness of CT-lymphography in sentinel lymph node navigation.

BACKGROUND: There are many methods for sentinel lymph node (SLN) navigation. The methods using radioisotopes and blue dyes are performed mainly for the identification of SLN. Our current method for SLN biopsy is a combination of three techniques with 99mTc-phytate, patent blue V dye, and preoperative CT-lymphography (CTLG). PATIENTS AND METHODS: Iomeprol (Iomeron®) as a water-soluble contrast agent is diluted twofold with 1 % lidocaine and intradermally injected into a few sites (2-5 ml at each site) around the tumor. After the injection, CT imaging is performed using a 64-row MDCT system (Siemens SOMATOM Definition AS+). We performed CTLG in 34 patients (16 men, 18 women) between September 2008 and March 2013. RESULTS: CTLG clearly visualized the SLN and the lymphatic drainage in 21 out of 34 patients. CONCLUSIONS: We can detect the SLN and lymphatic flow near to tumors without shine-through effect, especially in the head and neck regions. It is thought that CTLG may be useful to determine the range of lymph node dissection.

Arrhythmogenic superior vena cava manifesting after a right-sided pneumonectomy and mediastinal lymph node dissection.

No case of AF ablation after right-sided pneumonectomy has been reported, presumably because the pneumonectomy renders the ablation procedure more difficult than lobectomy because of the marked mediastinal displacement. In the case of catheter ablation of AF after right-sided pneumonectomy, it is extremely important to insert a mapping catheter not only into the PV but also into the SVC to accurately diagnose the site of abnormal electrical activity.

[Usefulness of Electron Density Calculated from Dual Energy CT in Differential Diagnosis between Hepatocellular Carcinoma and Hepatic Hemangioma].

PURPOSE: The aim of this study were to compare electron density (ED), obtained by dual energy computed tomography (DECT), between hepatocellular carcinoma (HCC) and hemangioma, and to assess the differential diagnostic performance of ED between HCC and hemangioma. METHODS: A total of 46 patients (27 men and 19 women; mean age, 65.7±14.0 years) diagnosed with HCC or hemangioma who underwent upper abdominal DECT between October 2021 and December 2022 were included. ED of each lesion was measured. Relative ED (rED), which is normalized by the ED of background liver parenchyma, was calculated. ED and rED of HCC and hemangioma were statistically analyzed. RESULTS: The HCC group showed significantly higher ED (48.1±5.2) and rED (80.0±7.3) than the hemangioma group (43.7±4.1, 69.7±7.2, respectively) (p<0.01). The area under the curve of rED was greater than that of ED, but no significant difference was found (p=0.153). CONCLUSION: ED may help in the differential diagnosis between HCC and hemangioma.

Liver fibrosis estimated using extracellular volume fraction obtained from dual-energy CT as a risk factor for hepatocellular carcinoma after sustained virologic response: A preliminary case-control study.

PURPOSE: To assess hepatocellular carcinoma (HCC) risk after sustained virologic response (SVR) through clinical data analyses, including evaluation of liver fibrosis using the extracellular volume fraction (ECV) obtained from dual-energy computed tomography (DECT). METHODS: Ninety-two patients (52 men and 40 women; mean age, 69.9 years) with hepatitis C virus infection after SVR underwent DECT of the liver (3-minute equilibrium-phase images) between January 2020 and March 2022. The ECV was calculated by measuring iodine density; fibrous markers, including ECV, fibrosis-4 index, aspartate aminotransferase to platelet ratio index, and platelet count, were statistically analyzed (p < 0.05). The risk factors associated with HCC were analyzed using univariate and multivariate logistic regression analyses. RESULTS: The ECV (26.1 ± 4.6 %) in patients with HCC (n,21) was significantly larger than the ECV (20.7 ± 3.3 %) in patients without HCC (n = 71) (p < 0.001). The cutoff value for the ECV was 24.3 %. The area under the operating characteristic curve of the ECV was 0.857, which was higher than that of the serum fibrosis markers. Older age, SVR achieved with interferon, alpha-fetoprotein level (>5 ng/mL), advanced fibrosis before treatment (>F3), and ECV were associated with HCC according to the univariate analysis. Multivariate analyses showed that ECV was the only factor independently associated with HCC (odds ratio 0.619, 95 % confidence interval 0.482-0.795, p < 0.001). CONCLUSION: Liver fibrosis estimated using ECV can be a predictive marker in patients with HCC after SVR.

Extracellular volume fraction obtained by dual-energy CT depicting the etiological differences of liver fibrosis.

PURPOSE: To assess etiological differences in extracellular volume fraction (ECV) and evaluate its influence on staging performance. METHODS: A total of 166 patients with normal liver (n = 14) and chronic liver disease related to viral hepatitis (n = 71), alcohol (n = 44), and nonalcoholic steatohepatitis (NASH) (n = 37) underwent dual-energy CT (DECT) of the liver (5-min equilibrium-phase images) between January 2020 and July 2022. The iodine densities of the parenchyma and aorta were measured and ECV was calculated. Comparisons of ECV between each etiology and METAVIR fibrosis stage were statistically analyzed (p < 0.05). RESULTS: ECV in each etiology and all patients significantly increased with higher fibrosis stage (p < 0.001) and showed a strong or moderate correlation with fibrosis stage (Spearman's ρ; all patients, 0.701; viral hepatitis, 0.638; alcoholic, 0.885; NASH, 0.791). In stages F2-F4, ECV in alcoholic liver disease was significantly larger than those for viral hepatitis and NASH (p < 0.05); however, no significant difference in stage F1 was found among the three etiologies. The cutoff values and areas under the receiver operating characteristic curve (AUC-ROCs) for discriminating fibrosis stage (≥ F1- ≥ F4) were higher for alcohol (cutoff values and AUC-ROC; 20.1% and 0.708 for ≥ F1, 23.8% and 0.990 for ≥ F2, 24.3% and 0.968 for ≥ F3, and 26.6% and 0.961 for ≥ F4, respectively) compared with those for the others. CONCLUSION: ECV in alcoholic liver disease is higher than that in other etiologies in the advanced stages of fibrosis, and etiological differences in ECV affect the staging performance of fibrosis.

Assessing the progression of segmental fibrosis in chronic liver disease using extracellular volume fractions.

PURPOSE: To assess the segmental difference of liver fibrosis during the progression of chronic liver disease (CLD) using hepatic extracellular volume fractions (fECVs) obtained by dual-energy CT. METHODS: A total of 218 patients (92 men and 126 women; mean age, 67.8 ± 11.7 years) with CLD and 85 patients (44 men and 41 women; mean age, 62.8 ± 13.7 years) without CLD as a control underwent dual-energy computed tomography (CT) of the liver (5-min equilibrium phase images). The iodine densities of the lateral, medial, anterior, and posterior segments and the aorta were measured, and fECVs were calculated. Comparisons of the fECV of each segment and for each albumin-bilirubin (ALBI) grade were then statistically analyzed. RESULTS: In the control group and ALBI grades 1 and 3, no significant difference in fECV was found between each segment, whereas in ALBI grade 2, the fECVs were significantly larger in the medial and anterior than in the other segments (p < 0.001). The fECVs of the lateral and posterior segments significantly increased with higher ALBI grade (p < 0.001). The fECVs of the medial and anterior segments were significantly increased with higher ALBI grade, up to grade 2 (p < 0.001), but no significant difference was found between ALBI grades 2 and 3. CONCLUSION: During the progression of CLD, fibrosis antecedently progressed in the medial and anterior segments, followed by the other liver segments.

[Usefulness of low- and medium-energy collimators in 123I-MIBG myocardial scintigraphy].

The heart-to-mediastinum (H/M) ratio on myocardial scintigraphy with (123)I-metaiodobenzylguanidine (MIBG) is used as a semi-quantitative index. However, the scatter from a photopeak of 529 keV on (123)I is thought to affect the H/M ratio, and collimator selection is important as well. We attempted to determine the usefulness of low- and medium-energy general purpose (LME) collimators by comparing them with low-energy high-resolution (LEHR) and medium-energy low-penetration (MELP) collimators in phantom and clinical studies. In the phantom study, we used a thoracic phantom and plastic bottles filled with (123)I-MIBG solution as upper limbs. Phantom images were acquired with LEHR, LME, and MELP collimators. Regions of interest were placed on the lung, mediastinum, heart, and liver. The average counts in the lung, coefficient of variation (CV%) in the heart, mediastinum, and liver, and H/M ratio were calculated. The H/M ratios obtained with the LEHR collimator and LME collimator were compared in a clinical study. We found that the average count in the lung measured with the LME collimator was reduced to about 30% of that obtained with the LEHR collimator in the phantom study. CV% measured with the LME collimator improved about 10% compared with that determined with the MELP collimator. The H/M ratio measured with the LME collimator was close to that measured with the MELP collimator. In the clinical study, the H/M ratios measured with the LEHR and LME collimators showed a positive relationship (y=2.1x-1.3, x; H/M with LEHR, y; H/M with LME) . LME collimators provided improved contrast and signal-to-noise ratio in evaluation of the H/M ratio on (123)I-MIBG myocardial scintigraphy.

[Method for determining scan timing based on analysis of formation process of the time-density curve].

A strict determination of scan timing is needed for dynamic multi-phase scanning and 3D-CT angiography (3D-CTA) by multi-detector row CT (MDCT) . In the present study, contrast media arrival time (T(AR)) was measured in the abdominal aorta at the bifurcation of the celiac artery for confirmation of circulatory differences in patients. In addition, we analyzed the process of formation of the time-density curve (TDC) and examined factors that affect the time to peak aortic enhancement (T(PA)). Mean T(AR) was 15.57+/-3.75 s. TDCs were plotted for each duration of injection. The rising portions of TDCs were superimposed on one another. TDCs with longer injection durations were piled up upon one another. Rise angle was approximately constant in response to each flow rate. Rise time (T(R)) showed a good correlation with injection duration (T(ID)). T(R) was 1.01 TID (R(2)=0.994) in the phantom study and 0.94 T(ID)-0.60 (R(2)=0.988) in the clinical study. In conclusion, for the selection of optimal scan timing it is useful to determine T(R) at a given point and to determine the time from T(AR).

[Dynamic contrast-enhanced T(1) measuring MRI using variable flip angle SPGR].

We modified the multi-phase spoiled gradient recalled echo (SPGR) pulse sequence using the double-echo MR technique for estimation of T(1) during the first pass of contrast agent, and examined its precision. In the first half of the pulse sequence, the flip angle was varied systematically to calculate static T(1) values. It was necessary to choose optimal flip angles to minimize the calculation error of static T(1) values. In the latter half of this sequence, changes in absolute T(1) were calculated using differences in signal intensities before and after the injection of contrast agent. The optimal flip angle was 20 degrees for precise conversion to T(1) values under the short TR (33.3 ms) condition. Double echo MR data were used to minimize the T(2)* effect. The present method appears to be useful for quantitative estimation of dynamic contrast-enhanced MRI.