Left ventricular functional analysis using 64-slice multidetector row computed tomography: comparison with left ventriculography and cardiovascular magnetic resonance.

OBJECTIVE: The progress in computed tomography (CT) has improved temporal resolution and shortened the acquisition time. We compared cardiac function using 64-slice CT with left ventriculography (LVG) and cardiovascular magnetic resonance (CMR). METHODS: A head-to-head comparison between CT, LVG and CMR was performed in 41 patients. In global LV function, CMR served as the reference. Regional wall motion was compared in a 5-point scoring system. RESULTS: CT had excellent intra- and interobserver reproducibility. Ejection fraction, end-diastolic and end-systolic volumes by CT were closely correlated with CMR (r = 0.95, 0.96 and 0.98, respectively), while LVG underestimated LV volumes (p < 0.01). The standard deviation of ejection fraction difference between CT and CMR was significantly lower than that between LVG and CMR (p = 0.0015). In regional function, there were good agreements of 94.8% (kappa = 0.82) between CT and LVG and 94.5% (kappa = 0.84) between CT and CMR. The intermethod agreements in mild hypokinesis using CT tended to be lower. CONCLUSION: An excellent correlation was observed between CT and CMR in the LV function over a wide range of heart rates. However, even though 64-slice CT tended to be less sensitive in detecting mild hypokinesis, it still showed excellent concordance in advanced regional abnormalities.

Comparison of contrast-enhanced MRI with (18)F-FDG PET/201Tl SPECT in dysfunctional myocardium: relation to early functional outcome after surgical revascularization in chronic ischemic heart disease.

UNLABELLED: Revascularization of viable myocardial segments has been shown to improve left ventricular (LV) function and long-term prognosis; however, the surgical risk is comparatively higher in patients with a low ejection fraction (EF). We compared contrast-enhanced MRI with (18)F-FDG PET/(201)Tl SPECT for myocardial viability and prediction of early functional outcome in patients with chronic coronary artery disease (CAD). METHODS: Forty-one patients with chronic CAD and LV dysfunction (mean age +/- SD, 66 +/- 10 y; 32 men; mean EF +/- SD, 38% +/- 13%) referred for (18)F-FDG PET, (201)Tl-SPECT and MRI within 2 wk were included. Twenty-nine subjects underwent coronary artery bypass grafting (CABG), and LV function was reassessed by MRI before discharge (17 +/- 7 d after surgery). Two were excluded from outcome analysis (1 death due to sepsis; 1 perioperative myocardial infarction). The extent of viable myocardium by (18)F-FDG PET/(201)Tl SPECT was defined by the metabolism-perfusion mismatch or ischemia, in comparison with the extent of delayed enhancement (DE) on MRI in a 17-segment model. Segmental functional recovery was defined as improvement in the wall motion score of > or =1 on a 4-point scale. EF and LV volume change were used as global functional outcome. RESULTS: Three hundred ninety-four dysfunctional segments were compared, and the extent of DE on MRI correlated negatively with the viability on (18)F-FDG PET. Of 252 dysfunctional segments that were successfully revascularized, the sensitivity, specificity, positive predictive value, and negative predictive value of PET/SPECT were 60.2%, 98.7%, 76.6%, and 96.7% and of MRI were 92.2%, 44.9%, 72.4%, and 78.6% using the cutoff value of 50% DE on MRI, without significant differences in overall accuracies. In 18 subjects who underwent isolated CABG, improvement of EF (> or =5%) and reverse LV remodeling (> or =10% LV size reduction) was best predicted by the no DE on MRI, and patients with substantial nonviable myocardium on (18)F-FDG/SPECT predicted a poor early functional outcome (all P < 0.001). CONCLUSION: Accurate prediction of early functional outcome by PET/SPECT and contrast-enhanced MRI is possible.

Evaluation of three-dimensional navigator-gated whole heart MR coronary angiography: the importance of systolic imaging in subjects with high heart rates.

PURPOSE: To evaluate the influence of heart rate (HR) on magnetic resonance coronary angiography (MRCA) image quality in diastolic and systolic phases. MATERIALS AND METHODS: Twenty-seven healthy volunteers (9 men; 33+/-9 years, HR 53-110 bpm), were evaluated with the electrocardiography and three-dimensional navigator-gating MRCA in a 1.5-T MR scanner (Avanto, Siemens) in diastolic and systolic phases (steady-state free precession; TR/TE/flip angle=3.2 ms/1.6 ms/90 degrees). The timing of scanning was individually adapted to the cardiac rest periods obtained in the prescanning, by visually identifying when the movement of right coronary artery was minimized during diastole and systole. Images of two phases were side-by-side compared on a four-point scale (from 1=poor to 4=excellent visibility; score of 3 or 4 as diagnostic). RESULTS: Of 13 subjects with HR < or =65 bpm (low HR group, mean 59.8+/-4.9 bpm, range 53-65), the image quality scores were significantly better than that with higher heart rates (73.9+/-9.0 bpm, range 68-110) in diastolic MRCA. The image quality was significantly improved during systole in high HR group. Overall, 91.3% of low HR group had MRCA image of diagnostic quality acquired at diastole, while 88.3% of high HR group had diagnostic images at systole by segmental analysis (p=NS). CONCLUSIONS: MRCA at systole offered superior quality in patients with high heart rates.

Morphologic and functional imaging of malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an aggressive tumor that arises from the pleura and frequently extends to adjacent structures. MPM cells produce and respond to many angiogenic factors, such as vascular endothelial growth factor (VEGF). VEGF expression in MPM is correlated with microvascular density, which is associated with poor survival. CT has been widely used as the primary imaging modality for the clinical evaluation of MPM. Major findings include nodular pleural thickening, unilateral pleural effusion, and tumor invasion of adjacent structures. CT tends to underestimate early chest wall invasion and peritoneal involvement and has well-known limitations in the evaluation of lymph node metastases. Perfusion CT can evaluate the microvasculature of tumors, while its disadvantages, such as high radiation exposure or side effects from iodinated contrast, limit its use in both research and clinical settings. MRI can provide additional information to CT. Because of its excellent contrast resolution, MRI is superior to CT, both in the differentiation of malignant from benign pleural disease, and in the assessment of chest wall and diaphragmatic involvement. Perfusion MRI is the most promising technique for the assessment of the tumor microvasculature. In MPM, therapeutic effects of chemotherapy can be monitored with perfusion MRI. It has been shown that FDG-PET is useful for the differentiation of benign from malignant lesions, for staging and monitoring metabolic response to therapy against MPM, and that it has prognostic value. An initial report on PET/CT imaging of MPM has shown increased accuracy of overall staging, improving the assessment of tumor resectability. PET/CT seems to be superior to other imaging modalities in detecting more extensive disease involvement, and identifying unsuspected occult distant metastases.

Thoracoabdominal-aortoiliac MDCT angiography using reduced dose of contrast material.

OBJECTIVE: The objective of our study was to compare the image quality of MDCT angiography studies obtained by injection of low doses of contrast medium with saline flush versus conventional doses of contrast medium. MATERIALS AND METHODS: Seventy-one patients with pre- or postoperative aortic aneurysms underwent MDCT angiography throughout the thoracoabdominal-aortoiliac system using an 8-MDCT scanner. In 37 patients, 100 mL of contrast medium was injected at a flow rate of 3.0 mL/s (hereafter referred to as the 100-mL group). In 34 patients, 50 mL of contrast medium followed by a 20-mL saline flush was injected at a flow rate of 2.5 mL/s (the 50-mL group). For each group, quantitative analysis involved calculating the mean aortoiliac enhancement, plateau deviation, and contrast enhancement in the pulmonary trunk and superior vena cava (SVC). Qualitative analysis involved assessing the 3D postprocessing images. RESULTS: Significant differences between the groups in mean aortoiliac enhancement (100-mL group vs 50-mL group, 337 +/- 6 H vs 319 +/- 5 H, p < 0.0001) and mean plateau deviation (51 +/- 4 H vs 58 +/- 4 H, p < 0.0001) were found. However, adequate arterial enhancement (>or= 200 H) was observed in 31 of 34 patients in the 50-mL group and uniform aortoiliac enhancement (< 50 H) was seen in 26 patients. Visual analysis showed no difference in contrast material magnitude and homogeneity between the groups. Furthermore, in the 50-mL group, the thoracic aorta was more clearly visualized because of a reduction in the opacity of the main pulmonary artery and SVC. CONCLUSION: In our experience, administration of 50 mL of contrast medium followed by a 20-mL saline flush produces thoracoabdominal-aortoiliac MDCT angiographic examinations of effective quality in most cases.

Comparison of myocardial blood flow induced by adenosine triphosphate and dipyridamole in patients with coronary artery disease.

Myocardial perfusion imaging with adenosine triphosphate (ATP) has been used increasingly to diagnose coronary artery disease (CAD) and assess risk for this disease. This study compared absolute myocardial blood flow (MBF) and myocardial flow reserve index (MFR) with ATP and dipyridamole (DIP) in patients with CAD. MBF was quantified by 15O-H2O PET in 21 patients with CAD (17 male, 4 female), aged 55 to 81 years. MBF was measured at rest, during intravenous injection of ATP (0.16 mg/kg/min), and again after DIP infusion (0.56 mg/kg). Regions of interest were drawn in nonischemic and ischemic segments based on findings from thallium-201 (201T1) scintigraphy and coronary angiography (CAG). Absolute MBF values and indexes of MFR were calculated in nonischemic and ischemic segments. Intravenous injection of ATP and DIP significantly increased MBF in nonischemic (2.4 +/- 0.9 and 2.1 +/- 0.8 ml/g/min, respectively; p < 0.01, for both) and in ischemic segments (1.3 +/- 0.4 and 1.5 +/- 0.4 ml/g/min, respectively; p < 0.01, for both). There was a significant difference in MBF values between ATP and DIP in nonischemic segments (p < 0.05), which was not observed in ischemic segments. In nonischemic segments, ATP produced higher MFR than DIP (2.1 +/- 0.8 and 1.8 +/- 0.7, respectively; p < 0.05), while no significant difference was observed in ischemic segments (1.5 +/- 0.6 and 1.7 +/- 0.3, respectively). ATP produced a greater hyperemia than DIP between the ischemic and nonischemic myocardium in patients with CAD. ATP is as effective as DIP for the diagnosis of CAD.

Effect of caffeine intake on myocardial hyperemic flow induced by adenosine triphosphate and dipyridamole.

UNLABELLED: The aims of this study were (a). to compare absolute myocardial blood flow (MBF) during adenosine triphosphate (ATP) infusion with that after dipyridamole administration without caffeine intake and (b). to evaluate the effect of caffeine intake on the hyperemic flow induced by these coronary vasodilator agents. METHODS: MBF was quantified with (15)O-labeled water and PET at rest, during ATP infusion (0.16 mg/kg/min for 9 min), and after dipyridamole administration (0.56 mg/kg over 4 min) after a 24-h abstinence from caffeine (baseline evaluation) in 10 healthy volunteers. Within 2 wk, the same PET studies were repeated after caffeine intake to evaluate the effect of caffeine on the hyperemic flow induced by these pharmacologic agents (caffeine study). Myocardial flow reserve (MFR), defined as the ratio of hyperemic to resting blood flow, was also evaluated. RESULTS: Resting MBF in baseline and caffeine studies did not differ significantly (0.79 +/- 0.29 vs. 0.75 +/- 0.31 mL/min/g, P = 0.88). Without caffeine intake, MBF during ATP infusion was significantly higher than that after dipyridamole administration (3.70 +/- 0.67 vs. 3.00 +/- 0.79 mL/min/g, P = 0.003), whereas there was no significant difference in MFR between ATP and dipyridamole stress (5.15 +/- 1.64 vs. 4.11 +/- 1.44, P = 0.07). After caffeine intake, the hyperemic flows induced by ATP and dipyridamole were not significantly different (1.68 +/- 0.37 vs. 1.52 +/- 0.40 mL/min/g, P = 0.50). MFR estimated by ATP and dipyridamole also did not differ significantly in the caffeine studies (2.44 +/- 0.88 vs. 2.25 +/- 0.94, P = 0.73). MBF during ATP infusion and after dipyridamole administration were significantly lower in the caffeine studies than that in the baseline evaluation (1.68 +/- 0.37 vs. 3.70 +/- 0.67 mL/min/g, P < 0.0001, and 1.52 +/- 0.40 vs. 3.00 +/- 0.79 mL/min/g, P < 0.0001, respectively). CONCLUSION: This study demonstrates that ATP has the potential to induce greater hyperemia than dipyridamole, whereas hyperemic responses to ATP and dipyridamole are similarly attenuated after caffeine intake. These findings suggest that abstinence from caffeine before ATP stress testing may be needed.

The effect of nitroglycerin on myocardial blood flow in various segments characterized by rest-redistribution thallium SPECT.

UNLABELLED: The use of nitrates is reported to be effective in viability detection in scintigraphic perfusion imaging. The purpose of the study was to evaluate the effect of nitroglycerin (NTG) on myocardial blood flow (MBF) and coronary vascular resistance (CVR) in various segments characterized by rest-redistribution (201)Tl SPECT. METHODS: Twenty-three patients with coronary artery disease underwent rest-redistribution (201)Tl SPECT and (15)O-labeled water PET at rest and after NTG spray (0.3 mg). In addition, 11 healthy volunteers were also studied using PET. RESULTS: NTG did not change global MBF in the volunteers or in the patients. In segments with normal (201)Tl uptake and in those with a severe irreversible (201)Tl defect, NTG significantly reduced MBF without changing CVR. NTG reduced CVR in segments with a reversible (201)Tl defect (141 +/- 50 to 114 +/- 29 mm Hg/[mL/min/g], P = 0.004) and in those with a mild-to-moderate irreversible (201)Tl defect (165 +/- 64 to 149 +/- 60 mm Hg/[mL/min/g], P = 0.003), while maintaining MBF. CONCLUSION: NTG preferentially reduces CVR in the viable myocardium with ischemia. After NTG, tracer uptake in the ischemic myocardium will be relatively increased compared with that in the nonviable and nonischemic myocardium, leading to improvements in viability detection.

Estimation of global and regional cardiac function using 64-slice computed tomography: a comparison study with echocardiography, gated-SPECT and cardiovascular magnetic resonance.

BACKGROUND: Sixty-four-slice multidetector spiral computed tomography (CT) has improved temporal resolution and reduced acquisition time. We aimed to evaluate the functional analysis using 64-slice CT comparing with echocardiography, electrocardiographically gated single-photon emission tomography (SPECT) and cardiovascular magnetic resonance (CMR). METHODS: Six-three patients (77.4+/-18.6 bpm) underwent 64-slice CT and CMR (echocardiography in 55; SPECT in 33) within 2 weeks were retrospectively reviewed. The left ventricular volumetric data from different methods were compared with CMR. Regional wall motion was compared between CT and CMR in a 17-segment and 4-point system (1=normal to 4=akinesis/dyskinesis). RESULTS: Ejection fraction (EF), end-diastolic volume (EDV) and end-systolic volume (ESV) by CT agreed well with CMR (bias+/-SD, -0.22%+/-4.18, r=0.97;-0.59 mL+/-15.21, r=0.98; 1.09 mL+/-10.61, r=0.99) over a wide range of left ventricular (LV) function (EF 18-76% by CMR). Our results also showed good correlation of EF measured by CT and echocardiography (r=0.87) or SPECT (r=0.91, all P<0.0001); however, standard deviation of EF difference between CT and CMR was significantly less than echocardiography or SPECT (P<0.005). For regional wall motion, an exact agreement of 97% (kappa=0.91) was found between CT and CMR. CONCLUSION: Sixty-four-slice CT agreed well with CMR in LV function assessment, and had a superior accuracy than echocardiography and SPECT on EF estimation. Sixty-four-slice CT is considered a clinically acceptable and robust method to evaluate LV function.

Complementary appearance of glucose and lipid metabolism in cardiac sarcoidosis.

Sarcoidosis is a non-caseating granulomatous systemic disease of unknown pathogenesis, and cardiac involvement is the most important prognostic factor. We have evaluated the value of the combined study of F-18 fluoro-2-deoxyglucose positron emission tomography and iodine-123 labeled 15-(p-iodophenyl)-3R,S-methylpentadecanoic acid single-photon emission tomography for the assessment of cardiac involvement of sarcoidosis, by comparing the findings with gadolinium magnetic resonance in a patient with histologically-proven cardiac sarcoidosis.

Structural and functional assessment of arrhythmogenic right ventricular dysplasia/cardiomyopathy by multi-slice computed tomography: comparison with cardiovascular magnetic resonance.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an uncommon inheritable cardiomyopathy involving predominant right ventricle with progressive fibrofatty tissue replacement. An integrated assessment of electrical, functional and anatomic abnormalities, in addition to personal and family history would be used to diagnose this disease entity. We present the case of a 69-year-old man with a history of sustained ventricular tachycardia. Fatty infiltration and regional wall motion abnormalities over biventricular myocardium were clearly demonstrated by cardiac 64-slice computed tomography (CT), as consistent with magnetic resonance imaging. Thus, multi-slice CT may have a significant role in the assessment and follow-up of patients with ARVD/C by providing excellent structural, functional assessment and tissue characterization.

Identification of lipomatous metaplasia in old infarcted myocardium by cardiovascular magnetic resonance and computed tomography.

Lipomatous metaplasia of myocardium after myocardial infarction (MI) is less reported, and the exact prevalence and clinical implications of this phenomenon are unclear. A case of lipomatous metaplasia after MI evaluated with cardiovascular magnetic resonance (CMR) and computed tomography (CT) is presented. The presence of lipomatous metaplasia could not be easily differentiated from scar simply by the delayed-enhanced images. Loss of signal on TrueFISP cine MRI can be a hint. A pre-contrast T1-weighted image with or without frequency-selective fat suppression is useful in order to verify the existence of lipomatous metaplasia on CMR.

Multidetector-row computed tomographic angiography of thoracic and abdominal aortic aneurysms: comparison of arterial enhancement with 3 different doses of contrast material.

OBJECTIVE: To compare the quality of multidetector-row computed tomographic angiography in patients with and without aortic aneurysms by 3 different amounts of contrast media (CM). METHODS: A total of 115 patients with aortic aneurysms were divided into 3 groups: group A, 100 mL CM; group B, 75 mL CM with 20 mL saline flush (SF); and group C, 50 mL CM with 20 mL SF. Twenty-five patients without aortic aneurysms were also enrolled (group D, 50 mL CM with 20 mL SF). Quantitative and qualitative analyses were performed by measuring attenuation in thoracoabdominal/aortoiliac lumen, aneurysmal lumen, and superior vena cava. RESULTS: In group C, attenuation was lower in distal than those in proximal and middle areas (P < 0.05). Contrast enhancement in abdominal aneurysmal lumen was more inhomogeneous in group C (P = 0.003). Visual analysis showed contrast enhancement was more nonuniform in group C (P = 0.004), and perivenous artifacts were more conspicuous in group A (P < 0.0001). CONCLUSIONS: Seventy-five milliliters CM followed by 20 mL SF can produce optimal contrast enhancement at systemic multidetector-row computed tomographic angiography in patients with aortic aneurysms.

Coronary angiography by 64-detector row computed tomography using low dose of contrast material with saline chaser: influence of total injection volume on vessel attenuation.

OBJECTIVE: To assess the influence of total injection volume on thoracic great vessels and coronary arteries enhancement in 64-detector row computed tomography (CT) coronary angiography using low dose of contrast material. METHODS: Sixty patients underwent cardiac CT (64 x 0.5 mm, 0.4 rot/s) using 40 mL of contrast material (350 mg of Iodine per milliliter) in 30 patients and 50 mL in 30 patients. Computed tomography densities (Hounsfield units) in ascending aorta, descending aorta, and main pulmonary artery were measured at every second with the time of CT data acquisition recorded in each reconstructed image. Computed tomography densities of proximal and distal coronary arteries were also measured. Differences in CT densities between 40 and 50 mL contrast material were assessed with the Student t test. In addition, the relation between the injection volume (mL) of contrast material per kilogram body weight and contrast enhancement in coronary arteries was studied. RESULTS: The average attenuations in the ascending and descending aorta and coronary arteries were significantly lower in 40-mL group than in 50-mL group (<0.05). In addition, the average attenuations in the pulmonary artery were significantly lower in 40-mL group than 50-mL group (<0.01). Every patient with the total injection volume of more than 0.9 mL/kg body weight showed a contrast enhancement more than 250 Hounsfield units. CONCLUSIONS: The reduction of total injection volume lowered the enhancement of thoracic great vessels and coronary arteries in 64-detector row cardiac CT. The injection volume of at least 0.9 mL/kg body weight was necessary for a steady contrast enhancement in coronary arteries.

Difference in myocardial flow reserve between patients with dilated cardiomyopathy and those with dilated phase of hypertrophic cardiomyopathy: evaluation by 15O-water PET.

BACKGROUND: The clinical features of patients with the dilated phase of hypertrophic cardiomyopathy (DHCM) may resemble those of patients with dilated cardiomyopathy (DCM); that is, systolic dysfunction and left ventricular dilatation. Myocardial flow reserve (MFR) is impaired in patients with nonischemic cardiomyopathy, and the reduced MFR may be related to poor prognosis. Several studies report that the mortality rate for patients with DHCM is higher than for DCM, but the difference between these 2 cardiomyopathies is still unclear. The purpose of this study was to assess the MFR of these 2 cardiomyopathies, using (15)O-water positron emission tomography (PET) to elucidate their differences. METHODS AND RESULTS: In total 30 patients were investigated: 23 with DCM (Group A) and 7 with DHCM (Group B). All those who were in a stable condition underwent cardiac catheterization. Myocardial blood flow (MBF) at rest and under ATP infusion was measured by (15)O-water PET, and the MFR was calculated. There were no significant differences in the hemodynamics of the 2 groups. The mean MFR in DHCM was significantly lower than that in DCM (1.49+/-0.31 vs 2.62+/-1.08; p=0.042), whereas MBF at rest did not differ (DCM vs DHCM: 0.66+/-0.20 vs 0.49+/-0.05 ml . min(-1) . g(-1); NS). The MFR in both Group A and B was significantly decreased compared with the normal controls (MFR in normal controls: 5.15+/-1.64, p=0.00015, 0.00013, respectively). CONCLUSIONS: These results suggest that impaired vasodilatation (ie, dysfunction of the microcirculation) is more severe in patients with DHCM than in patients with DCM, even though patients' characteristics and hemodynamics do not differ.

Myocardial viability by contrast-enhanced cardiovascular magnetic resonance in patients with coronary artery disease: comparison with gated single-photon emission tomography and FDG position emission tomography.

BACKGROUND: The aim of this study was to assess the value of contrast-enhanced cardiovascular magnetic resonance (CMR) in viability for patients with coronary artery disease and left ventricular (LV) dysfunction (ejection fraction [EF] /=50% maximal (201)Tl activity) and CMR (/=50% of maximal FDG uptake) detected more viability (9%). CONCLUSION: The extent of DE correlated (201)Tl activity well. CMR could detect more small infarcts, while FDG-PET could detect more viability. CMR could distinguish between artifacts or infarction on SPECT, especially in poor LV function.

Cardiac functional analysis by free-breath real-time cine CMR with a spatiotemporal filtering method, TSENSE: comparison with breath-hold cine CMR.

The aim of this study was to assess the accuracy of cardiac functional values obtained from free-breathing real-time cine CMR with the temporal sensitivity encoding (TSENSE) technique by comparing them with values obtained from conventional cine CMR. For the real-time cine CMR, two protocols were employed, one with good temporal resolution and one with good spatial resolution. The functional values obtained from the high temporal resolution real-time cine CMR agreed and correlated well with those of cine CMR. On the other hand, statistically significant but clinically slight overestimation of ESV (p < .05) and underestimation of EF (p < .01) were observed with the other protocol. Real-time cine CMR with TSENSE can provide acceptable cardiac functional values.

Demonstration of cardiac involvement of sarcoidosis by contrast-enhanced multislice computed tomography and delayed-enhanced magnetic resonance imaging.

Delayed-enhanced magnetic resonance (MR) imaging has recently been shown to be effective in detecting cardiac sarcoidosis. Two cases in which contrast-enhanced multislice computed tomography imaging clearly identified the localization and extension of cardiac sarcoidosis as delayed-enhanced MR imaging are presented.