Yi-Luan Huang

Sequential Changes of Myocardial Microstructure in Patients Postmyocardial Infarction by Diffusion-Tensor Cardiac Mr Correlation with Left Ventricular Structure and Function

Background—We used diffusion-tensor cardiac MR to investigate myocardial microstructure changes, including tissue integrity (mean diffusivity [MD], fractional anisotropy) and fiber architecture (helix angles) in patients with recent myocardial infarction (MI). This study aimed to investigate the sequential changes of myocardial microstructure and its relationships with changes of macrostructure and function of the left ventricle post-MI. Methods and Results—Seventeen patients (age, 55.1±11.5 years; all men) participated in the follow-up study. Diffusion-tensor cardiac MR, cine gradient echo for left ventricle function, and late gadolinium enhancement for viability were measured from recent to chronic MI (median interval, 191 days). When compared with the remote zone, the infarct-adjacent zone showed overall increase of MD (2-way MANOVA, F1,16=36.3; P<0.001), decrease of fractional anisotropy (F1,16=5.8; P=0.029), and decrease of mean helix angles (F1,16=62.0; P<0.001). From recent to chronic MI, there was overall sequential decrease of MD (F1,16=22.6; P<0.001) and increase of fractional anisotropy (F1,16=7.8; P=0.013). Multiple linear regression showed that the improvement of wall thickening in the infarct-adjacent zone correlated with sequential decrease of MD in the infarct-adjacent zone (r=−0.70; P=0.002) and increase of mean helix angles (ie, more right-handed helical myofiber reorientation, predominantly subendocardial location) in the remote zone (r=0.60; P=0.011). Likewise, wall thickening in the remote zone correlated with MD in the remote zone (r=−0.72; P=0.001) and mean helix angles in the infarct-adjacent zone (r=0.72; P=0.001). Conclusion—Diffusion-tensor cardiac MR suggests that sequential zonal improvement of tissue integrity and fiber architecture remodeling both associate with sequential recovery of zonal wall thickening of the left ventricle from recent to chronic MI.

Coronary arterial calcification on low-dose ungated MDCT for lung cancer screening: concordance study with dedicated cardiac CT.

OBJECTIVE Coronary artery calcification (CAC) is frequently detected on low-dose ungated MDCT performed for lung cancer screening. We aimed to determine the concordance of CAC scores on low-dose ungated and regular-dose ECG-gated MDCT. SUBJECTS AND METHODS The subjects were 513 patients consecutively registered for health screening and undergoing both low-dose ungated (120 kVp, 20 mAs) and regular-dose ECG-gated MDCT (120 kVp, 150 mAs, retrospective ECG gating). The first 30 cases were used for protocol optimization and a training session. Agatston score on regular-dose ECG-gated and low-dose ungated MDCT in the other 483 cases (320 men; mean age, 62.2 +/- 13.2 [SD] years) was calculated by two observers in a blinded manner. Interobserver and intertechnique scoring variability and concordance were calculated. RESULTS The mean of interobserver scoring variability for regular-dose ECG-gated MDCT was 3.6% and for low-dose ungated MDCT was 9.6%. Regular-dose ECG-gated MDCT depicted CAC in 221 (46%) of the subjects. With low-dose ungated MDCT, observers 1 and 2, respectively, had five and seven false-positive and five and four false-negative predictions. All the miscategorized scores were 12 or less. The negative predictive values of CAC on low-dose ungated MDCT were 98% and 99% for observers 1 and 2, respectively. For patients with CAC, the mean intertechnique scoring variability was 40-43%. For all 483 subjects, the intertechnique concordance of the four major score ranks (0, 1-100, 101-400, > 400) was high (kappa = 0.89 for the two observers). CONCLUSION Low-dose ungated MDCT with an optimized protocol is reliable for prediction of the presence of CAC and categorization of the four major Agatston score ranks. This technique may be useful for coronary artery disease risk stratification of persons undergoing low-dose ungated MDCT for lung cancer screening.

Intramural Blood Pools Accompanying Aortic Intramural Hematoma: CT Appearance and Natural Course

PURPOSE To evaluate multidetector computed tomographic (CT) images to investigate the prevalence, morphology, natural course, and prognostic effect of intramural blood pools (IBPs) in patients with acute intramural hematoma (IMH). MATERIALS AND METHODS Institutional review board approval and written informed consent were obtained. Sixty-five patients (41 men; mean age, 65.9 years ± 11.3 [standard deviation]) with acute IMH undergoing three or more multidetector CT examinations during follow-up for 12 months or longer (median = 18 months), except for those undergoing surgery (n = 16), were enrolled. Associated factors of developing and resorption of IBP in IMH were analyzed by using logistic regression. RESULTS There were 40 IBPs in 10 patients at initial multidetector CT, and 15 new IBPs developed in 11 patients during follow-up. IBPs occurred most in the descending thoracic (55% [31 of 56]) and abdominal (41% [23 of 56]) aorta in 28% (18 of 65) of patients. During 33.8 months (range, 2.8-50 months) of follow-up in these 18 patients, 57% (32 of 56) of IBPs showed complete resorption in 15 patients, 29% (16 of 56) of IBPs showed incomplete resorption in eight patients, and 14% (eight of 56) of IBPs had interrupted follow-up because of surgery or death in three patients. Logistic regression showed that age younger than 70 years (odds ratio [OR], 8.74; 95% confidence interval [CI]: 1.03, 76.9) and IMH wall thickness greater than 10 mm (OR, 4.93; 95% CI: 1.04, 23.0) were associated with developing IBP at initial multidetector CT, while IBP with larger transmural diameter (OR, 1.16; 95% CI: 1.02, 1.31) and multidetector CT-demonstrated connection with intercostal or lumbar artery (63% [35 of 56]) (OR, 5.44; 95% CI: 1.43, 20.9) were associated with incomplete resorption. CONCLUSION IBPs are frequently observed at multidetector CT in patients with IMH. They may resolve over time or appear during follow-up. These findings are not associated with a poor prognosis, and IBPs should be distinguished from ulcerlike projections.

Identification and viability assessment of infarcted myocardium with late enhancement multidetector computed tomography: Comparison with thallium single photon emission computed tomography and echocardiography

BACKGROUND Recent studies revealed that multidetector computed tomography late enhancement (MDCT-LE) is a reliable technique for detecting necrotic and scarred myocardial tissue. The aims of the study were to identify infarcted myocardium using MDCT-LE protocol in patients after myocardial infarction (MI) and assess viability in resting wall motion abnormalities. METHODS One hundred one patients with previous MI (62 +/- 13 years, 1-6 months after MI) underwent MDCT-LE (15 minutes after contrast medium administration), rest-redistribution thallium single photon emission computed tomography (Tl-SPECT), and dobutamine echocardiography (DbE). In a 17-segment model, infarcted myocardium detected by MDCT-LE was categorized as none, 1%-25%, 26%-50%, 51%-75%, or >75% segmental extent and was compared with decreased uptake of Tl-SPECT and contractile function by DbE on per patient and segmental basis in a blinded fashion. RESULTS By per patient analysis, MDCT-LE identified the presence of infarcted myocardium in 97 patients (96%), and Tl-SPECT decreased uptake in 88 patients (87%), (P = .02). By per segment analysis, the concordance for detecting infarcted myocardium was good (kappa value = 0.792). In segments with resting wall motion abnormalities (N = 486), there was moderate concordance in assessing viability (kappa value between MDCT and Tl-SPECT = 0.555, MDCT and DbE = 0.498, Tl-SPECT and DbE = 0.478) with predefined MDCT-LE threshold of 50% segmental extent. Among segments with MDCT-LE >75% segmental extent, the proportion designated nonviable by Tl-SPECT and DbE reached 87.8% and 92.2%, respectively. CONCLUSIONS Multidetector computed tomography late enhancement is accurate in identifying the presence and extent of infarcted myocardium. Its segmental extent has good correlation with the magnitude of thallium decreased uptake and can predict contractile reserve. Multidetector computed tomography late enhancement can be an alternative to assess viability.

Percutaneous retrieval of dislodged central venous port catheter: experience of 25 patients in a single institute:

Background: For a dislodged port catheter, percutaneous retrieval by using a loop snare or a basket is the standard technique, with high success. However, once a loop snare fails, the likelihood of success with other tools is considered low. Purpose: To report our experience of percutaneous retrieval of dislodged port catheters and to emphasize the usefulness of grasping forceps. Material and Methods: During a 6-year period, a total of 25 dislodged port catheters were retrieved in our institute. The interval between port catheter implantation and dislodged catheter retrieval was 3–85 months (mean 23 months). The time of delayed retrieval ranged from 3 to 604 days (mean 58 days). A loop snare or grasping forceps were used via either the femoral or jugular route. Results: The prevalence of port catheter dislodgement was 0.4% in our institute. All dislodged port catheters were successfully removed, including four patients with delayed retrieval of more than 90 days. A loop snare was used in 20 patients, with technical success in 18. Grasping forceps were used in seven patients, all with success (including the two patients who failed by initial use of a loop snare). No procedure-related complications were encountered, except transient arrhythmia in four patients requiring no medication. Conclusion: Although the prevalence of port catheter dislodgement is low, percutaneous attempts at retrieval should be performed in all patients, even in chronic settings. A loop snare is the instrument of choice for retrieval. Grasping forceps can be used as an auxiliary instrument, especially in patients where a loop snare fails.

Dual-phase multi-detector computed tomography assesses jeopardised and infarcted myocardium subtending infarct-related artery early after acute myocardial infarction

Objectives: To investigate dual-phase multi-detector computed tomography (MDCT) for assessing extent and severity of jeopardised and infarcted myocardium subtended by infarct-related artery (IRA), and its indication for revascularisation after acute myocardial infarction (AMI). Designs, setting and patients: Prospective, single-centre study included 107 patients with uncomplicated post-AMI 3–7 days, who met criteria and underwent dual-phase 64-slice MDCT. IRA, culprit lesion and extent of jeopardised/infarcted myocardium were assessed by three-dimensional (3D) volume-rendered images with myocardium maps and computed tomography angiography (CTA), compared with stress-redistribution thallium-201 single-photon emission computed tomography (SPECT) plus conventional coronary angiography (CCA). MDCT-jeopardised score (severity of jeopardised myocardium) was defined as extent of jeopardised myocardium multiplied by the weighted factor dependent on culprit lesion severity compared with SPECT-SRS (summation of segmental reversible score). The IRA indication for revascularisation was evaluated by MDCT-jeopardised score plus CTA. SPECT-SRS ⩾2 plus CCA-culprit lesion ⩾50% was the standard reference. Results: The presence of MDCT-delayed enhancement was found in 101 (94.4%) patients. The IRA and culprit lesion were identified in 99 (92.5%) patients by MDCT-myocardium maps plus CTA. The concordance between MDCT and SPECT for detecting infarcted myocardium was good (kappa = 0.702). The correlation between MDCT-jeopardised score and SPECT-SRS was 0.741. The correlation between CTA and CCA for culprit lesion severity was 0.85. The sensitivity, specificity, negative and positive predictive values of MDCT-jeopardised score ⩾2.5 plus CTA for indicating revascularisation were 90.2%, 80.4%, 86.0% and 85.9%, respectively. Conclusions: Dual-phase MDCT has good accuracy for identifying IRA, and assessing infarcted and jeopardised myocardium for clinical relevance. It provides an alternative for triage and therapeutic planning in post-AMI.

Temporal correlation-based dynamic contrast-enhanced MR imaging improves assessment of complex pulmonary circulation in congenital heart disease†

A temporal correlation (TC) mapping method is proposed to help bolus chasing during dynamic contrast‐enhanced (DCE) MRI of complex pulmonary circulation (CPC) in patients with congenital heart disease. DCE‐MRI was performed on five healthy male subjects (23–24 years old) and 25 patients (nine males and 16 females, 0.25–44 years old), and TC maps were generated by performing pixel‐based computation of cross‐correlations to the pulmonary artery with a series of time shifts in all subjects. Qualitative and quantitative evaluations were performed in comparison with original DCE images. TC maps exhibited a better signal‐to‐noise ratio (SNR) by factors of 4.3 and 1.3 in the lung parenchyma, pulmonary veins, and superior artery/vein; a better intraparenchymal contrast‐to‐noise ratio (CNR) by factors of 1.5–5.4; and a significantly higher conspicuity in all regions except the pulmonary arteries when graded with a five‐point score. TC maps evaluated by two experienced clinicians significantly added relevant information (P < 0.001), and in some cases affected the final diagnosis. We conclude that TC maps facilitate bolus chasing for DCE‐MRI by reducing recirculation effects and interframe fluctuations, and hence complements morphological imaging of CPC in patients with complex congenital heart disease. Magn Reson Med, 2006.

Inflow-weighted pulmonary perfusion: comparison between dynamic contrast-enhanced MRI versus perfusion scintigraphy in complex pulmonary circulation

BackgroundDue to the different properties of the contrast agents, the lung perfusion maps as measured by 99mTc-labeled macroaggregated albumin perfusion scintigraphy (PS) are not uncommonly discrepant from those measured by dynamic contrast-enhanced MRI (DCE-MRI) using indicator-dilution analysis in complex pulmonary circulation. Since PS offers the pre-capillary perfusion of the first-pass transit, we hypothesized that an inflow-weighted perfusion model of DCE-MRI could simulate the result by PS.Methods22 patients underwent DCE-MRI at 1.5T and also PS. Relative perfusion contributed by the left lung was calculated by PS (PSL%), by DCE-MRI using conventional indicator dilution theory for pulmonary blood volume (PBVL%) and pulmonary blood flow (PBFL%) and using our proposed inflow-weighted pulmonary blood volume (PBViwL%). For PBViwL%, the optimal upper bound of the inflow-weighted integration range was determined by correlation coefficient analysis.ResultsThe time-to-peak of the normal lung parenchyma was the optimal upper bound in the inflow-weighted perfusion model. Using PSL% as a reference, PBVL% showed error of 49.24% to −40.37% (intraclass correlation coefficient RI = 0.55) and PBFL% had error of 34.87% to −27.76% (RI = 0.80). With the inflow-weighted model, PBViwL% had much less error of 12.28% to −11.20% (RI = 0.98) from PSL%.ConclusionsThe inflow-weighted DCE-MRI provides relative perfusion maps similar to that by PS. The discrepancy between conventional indicator-dilution and inflow-weighted analysis represents a mixed-flow component in which pathological flow such as shunting or collaterals might have participated.

Aortic intramural hematoma with pulmonary artery extension mimics pulmonary embolism.

A 59-year-old woman presented to emergency department with sudden onset of chest tightness and shortness of breath. Laboratory test revealed elevated D-dimer (1558 ng/mL). The electrocardiogram revealed right axis deviation, S1Q3T3 pattern, and T-wave inversion in leads V1 to V6. Computed tomographic angiography (CTA) was performed with 64-slice computed tomography for suspicious of pulmonary embolism. Contrast-enhanced CTA showed no filling defect in the pulmonary arteries; however, luminal narrowing of the right pulmonary artery was noted. Nonenhanced computed tomographic scan showed smooth eccentric high attenuation change along the wall of main pulmonary artery and right pulmonary artery and also along the ascending and descending aorta. The high attenuation lesions in both of the aorta and pulmonary artery showed no contrast enhancement indicating presence of intramural hematoma (IMH). Based on the image findings, a diagnosis of type A aortic IMH with pulmonary artery extension, instead of chronic pulmonary embolism, was made. Follow-up CTA 3 months later showed much improved of the right pulmonary artery narrowing and nearly complete resolution of the IMH.

CT of Coronary Heart Disease: Part 2, Dual-Phase MDCT Evaluates Late Symptom Recurrence in ST-Segment Elevation Myocardial Infarction Patients After Revascularization

OBJECTIVE The purpose of the study was to investigate dual-phase MDCT for assessing obstructive lesions and the extent and severity of the subtending myocardium at risk in patients presenting with chest pain syndromes 9 or more months after having undergone revascularization for the treatment of ST-segment elevation myocardial infarction (STEMI). MATERIALS AND METHODS Dual-phase 64-MDCT was performed on 135 patients with recurring chest symptoms 9 months or more after revascularization (mean ± SD, 23 ± 11 months after index invasive angiogram for treatment of STEMI). Obstructive lesions (≥ 50% stenosis) were detected by MDCT angiography and the extent of myocardium at risk was detected by delayed phase 3D myocardium maps. A myocardium at-risk score based on MDCT findings was defined as the extent of myocardium at risk governed by the coronary lesion and weighted by lesion severity. Results were compared with stress-redistribution (201)Tl-SPECT and invasive angiography. RESULTS In restenotic, new, progressive, and previously obstructive lesions that are not currently progressive, analysis of assessable segments (1966/2025, 97.1%) obtained true-positive detection rates of 88.1%, 88.6%, 82.9%, and 100%, respectively; false-negative detection rates were 5.3%, 1.6%, 2.9%, and 8.8%. In 124 patients (91.9%) in whom all segments were assessable, the MDCT-based myocardium at-risk score correlated with the SPECT-based summed difference score (SDS) (r = 0.841, p < 0.001). For detecting SPECT-based SDS ≥ 1 and SDS > 3, areas under the receiver operating characteristic curve for the MDCT-based myocardium at-risk score were 0.874 (95% CI, 0.805-0.942) and 0.938 (95% CI, 0.895-0.981), with optimal cutoff values of 2.68 and 5.01, respectively. CONCLUSION Dual-phase MDCT is useful in detecting different patterns of obstructive lesions and the extent of myocardium at risk as an alternative for therapeutic planning in patients presenting with late symptoms after treatment for acute myocardial infarction.