Masaki Yamamuro

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-detecter row computed tomography (CT) coronary angiography using low dose of contrast material. Methods: Sixty patients underwent cardiac CT (64 × 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.

Comparison of Contrast-Enhanced MRI with 18F-FDG PET/201Tl SPECT in Dysfunctional Myocardium: Relation to Early Functional Outcome After Surgical Revascularization in Chronic Ischemic Heart Disease

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 18F-FDG PET/201Tl 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 18F-FDG PET, 201Tl-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 18F-FDG PET/201Tl 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 ≥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 18F-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 (≥5%) and reverse LV remodeling (≥10% LV size reduction) was best predicted by the no DE on MRI, and patients with substantial nonviable myocardium on 18F-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.

Multimodality Imaging of Cardiac Sarcoidosis Before and After Steroid Therapy

A 65-year-old woman was referred to our hospital because of chest pain. Right ventricular bundle-block was noted on the ECG. Angiotensin-converting enzyme level was elevated (33.2 IU/L). Delayed-enhanced magnetic resonance imaging (MRI) using an inversion-recovery segmented gradient echo sequence performed 15 minutes after gadolinium contrast injection (0.15 mmol/kg of gadodiamide) disclosed hyperenhancement, mainly in the outer layer of the septal, inferior, and anterolateral walls (Figure 1A). Cine MRI revealed wall motion abnormalities in septal and inferior walls (Figure 1B and 1C; Movie I). Left ventricular ejection fraction was 44%. Resting 201thallium single photon emission tomography revealed perfusion defects in these walls (Figure 1D). Positron emission tomography with 18fluorodeoxyglucose (FDG PET) imaging performed in a fasting condition …

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% (ĸ = 0.82) between CT and LVG and 94.5% (ĸ = 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.

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.

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.

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.

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.

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 by15O-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 fhallium-201 (2O1T1) 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 m//g/min, respectively; p < 0.01, for both) and in ischemic segments (1.3 ± 0.4 and 1.5 ± 0.4 m//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.

Primary cardiac lymphoma demonstrated by Delayed contrast-enhanced magnetic resonance imaging

Delayed contrast-enhanced magnetic resonance (MR) imaging that nullifies the signal of normal myocardium produces great differences in myocardial signal intensity between normal and infarcted myocardium. A case of primary cardiac lymphoma is presented in which delayed contrast-enhanced MR imaging clearly identified the localization and extension of a lymphoma infiltrating the myocardium.