Tomonari Kiriyama

FDG-PET/CT in the diagnosis of recurrent breast cancer

Background An advantage of PET/CT has been demonstrated for diagnosis of several tumor entities. In patients with breast cancer, early diagnosis and accurate restaging of recurrence after surgery is important for selection of the most appropriate therapeutic strategy. Purpose To evaluate the accuracy of integrated positron emission tomography and computed tomography (PET/CT) using 18F-fluorodeoxyglucose (FDG), for follow-up of patients with suspected recurrent breast cancer. Material and Methods Forty-seven patients with suspected recurrent breast cancer underwent PET/CT. The PET and PET/CT images were interpreted without knowledge of the results of other diagnostic modalities, and compared with each other with reference to the final diagnosis. Results Twenty-five (53%) patients suffered tumor recurrence. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 96%, 91%, 92%, 95%, and 94%, respectively. In comparison with PET, PET/CT had a higher sensitivity and accuracy (96% vs. 80% and 94% vs. 81%, respectively). The difference in diagnostic accuracy between PET/CT and PET was significant (P < 0.05). Conclusion The present findings indicate that PET/CT is an accurate, sensitive and reliable modality for screening and detection of breast cancer recurrence. PET/CT appears to be an effective surveillance tool, as it is able to cover the whole body in a single procedure and shows good performance.

Anemia and the risk of contrast-induced nephropathy in patients with renal insufficiency undergoing contrast-enhanced MDCT

PURPOSE The purpose of this study was to assess the effect of anemia on the incidence of contrast-induced nephropathy (CIN) in patients with renal impairment undergoing MDCT. MATERIALS AND METHODS Institutional review board approval was waived for this retrospective review of 843 patients with stable renal insufficiency (eGFR between 15 and 60 mL/min) who had undergone contrast-enhanced MDCT. Baseline hematocrit and hemoglobin values were measured. Serum creatinine (SCr) was assessed at the baseline and at 48-72 h after contrast administration. RESULTS The overall incidence of CIN in the patient population with renal insufficiency was 6.9%. CIN developed in 7.8% (54 of 695) of anemic patients, and in 2.8% (4 of 148) of non-anemic patients (P=.027). After adjustment for confounders, low hemoglobin and low hematocrit values remained independent predictors of CIN (odds ratio 4.6, 95% CI 1.0-20.5, P=.046). CONCLUSIONS Anemia is associated with a higher incidence of CIN in patients with renal insufficiency. Anemia is a potentially modifiable risk factor for CIN, and has an unfavorable impact on prognosis in patients with renal insufficiency undergoing contrast-enhanced MDCT.

Beam-hardening artifacts on computed tomography images caused by lanthanum carbonate hydrate in a patient on dialysis

Lanthanum carbonate hydrate is a nonaluminum, noncalcium phosphate binder containing lanthanum (La). It is effective in decreasing the serum phosphate level in patients on dialysis. Because the atomic number of the La contained in lanthanum carbonate hydrate is relatively high, at 57, this agent may cause strong artifacts on computed tomography (CT) images, which may be mistakenly interpreted as foreign bodies. We recently performed CT examination of a patient on Fosrenol chewable tablets (i.e., lanthanum carbonate hydrate). The CT images were difficult to evaluate because of strong beam hardening artifacts, and differentiation from foreign body aspiration was required. We report here our experience and a discussion of the characteristics of this artifact.

A left ventricular lipoma diagnosed on three-dimensional electrocardiogram-gated cardiac computed tomography

Cardiac lipomas are extremely rare primary benign cardiac tumors. We describe a patient with a chief complaint of ventricular tachycardia associated with a lipoma arising in the left ventricular myocardium. The cardiac lipoma was qualitatively evaluated and its location was accurately determined noninvasively with the use of three-dimensional images reconstructed from data acquired by electrocardiogram-gated cardiac computed tomography (CT). Our experience suggests that high-resolution three-dimensional CT imaging may facilitate the determination of strategies for surgical treatment.

Simultaneous assessment of myocardial scar and coronary arteries using navigator-gated 3-dimensional fat-suppressed delayed-enhancement MRI at 3.0 T: a technical feasibility study.

Objective To assess technical feasibility of navigator-gated 3-dimensional (3D) fat-suppressed delayed-enhancement magnetic resonance imaging (DE-MRI) at 3.0 T for simultaneous visualization of myocardial scars and coronary arteries. Methods Thirty patients with various myocardial diseases underwent navigator-gated 3D fat-suppressed DE-MRI using a 3.0-T scanner. The ability of this imaging technique to detect myocardial scars was compared with that of 2D DE-MRI. Visualization of the coronary arteries by this MRI technique was scored, and the relationship between myocardial scars and coronary arteries was assessed. Results Navigator-gated 3D fat-suppressed DE-MRI detected 71 of 75 segments with a myocardial scar. This imaging visualized proximal coronary arteries with an acceptable image quality and demonstrated a relationship between the myocardial scars and coronary arteries in 11 of the patients with scars. Conclusion Navigator-gated 3D fat-suppressed DE-MRI at 3.0 T was feasible for simultaneous visualization of myocardial scars and proximal coronary arteries.

Interpretative Variability and Its Impact on the Prognostic Value of Myocardial Fatty Acid Imaging in Asymptomatic Hemodialysis Patients in a Multicenter Trial in Japan

BACKGROUND The severity of impaired fatty acid utilization in the myocardium can predict cardiac death in asymptomatic patients on hemodialysis. However, interpretive variability and its impact on the prognostic value of myocardial fatty acid imaging are unknown. METHODS AND RESULTS A total of 677 patients who received hemodialysis for ≥ 20 years and had one or more cardiovascular risk factors underwent (123)I-labeled β-methyl iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) at 48 hospitals across Japan. SPECT images were interpreted by experts at the nuclear core laboratory and by readers with varying skill levels at clinical centers, based on the standard 17-segment model and 5-point scoring systems, independently. The κ values only reached fair agreement both for overall impression (κ=0.298, normal vs. abnormal) and for categorical impression (κ=0.244, normal vs. mildly abnormal vs. severely abnormal). The normalcy rate was lower in readers at the clinical centers (60.9%) than in experts (69.9%). In contrast to the results assessed by experts, a Kaplan-Meier analysis based on the interpretation by readers at the clinical centers failed to distinguish the risk of events in patients with normal scans from that of patients with mildly abnormal scans. CONCLUSIONS Considerable variability and its impact on prognostic value were observed in the visual interpretation of BMIPP SPECT images between experts and readers at the clinical centers.

Usefulness of Single Photon Emission Computed Tomography/Computed Tomography Fusion-Hybrid Imaging to Evaluate Coronary Artery Disorders in Patients with a History of Kawasaki Disease.

BACKGROUND The coronary arterial lesions of Kawasaki disease are mainly dilative lesions, aneurysms, and stenotic lesions formed before, after, and between aneurysms; these lesions develop in multiple branches resulting in complex coronary hemodynamics. Diagnosis of myocardial ischemia and infarction and evaluation of the culprit coronary arteries and regions is critical to evaluating the treatment and prognosis of patients. This study used hybrid imaging, in which multidetector computed tomographic (CT) images for coronary CT angiography (CCTA) and stress myocardial perfusion single-photon emission CT (SPECT) images were fused. We investigated the diagnosis of blood vessels and regions responsible for myocardial ischemia and infarction in patients with complex coronary arterial lesions; in addition, we evaluated myocardial lesions that developed directly under giant coronary artery aneurysms. METHODS The subjects were 17 patients with Kawasaki disease with multiple coronary arterial lesions (median age, 18.0 years; 16 male). Both CCTA using 64-row CT and adenosine-loading myocardial SPECT were performed. Three branches, the right coronary artery (RCA), left anterior descending branch (LAD), and left circumflex branch, were evaluated with the conventional side-by-side interpretation, in which the images were lined up for diagnosis, and hybrid imaging, in which the CCTA and SPECT images were fused with computer processing. In addition, the myocardial lesions directly under giant coronary artery aneurysms were investigated with fusion imaging. RESULTS Images sufficient for evaluation were acquired in all 17 patients. In the RCA, coronary arterial lesions were detected with CCTA in 16 patients. The evaluations were consistent between the side-by-side and fusion interpretation in 14 patients, and the blood vessel responsible for the myocardial ischemic region was identified in 2 patients. In the left circumflex branch, coronary arterial lesions were confirmed with 3-dimensional CT in 5 patients, and the the culprit coronary arteries for myocardial ischemia/infarction were confirmed with the fusion interpretation but not with the side-by-side interpretation. In the LAD, coronary arterial lesions were present in all patients, and the diagnosis was made with the fusion interpretation in 10 patients. In the LAD, small-range infarct lesions were detected directly under the giant coronary artery aneurysm in 8 patients, but were not confirmed with the side-by-side interpretation. CONCLUSION Fusion imaging was capable of accurately evaluating myocardial ischemia/infarction as cardiovascular sequelae of Kawasaki disease and confirming the culprit coronary arteries. In addition, analysis of fusion images confirmed that small-range infarct lesions were concomitantly present directly under giant coronary artery aneurysms in the anterior descending coronary artery.

Diagnostic Imaging of Pulmonary Thromboembolism by Multidetector-row CT

For diagnosis of pulmonary thromboembolism, multidetector-row computed tomography (CT) is a minimally invasive imaging technique that can be performed rapidly with high sensitivity and specificity, and has been increasingly employed as the imaging modality of first choice for this disease. Since deep vein thrombosis in the legs, which is important as a thrombus source, can be evaluated immediately after the diagnosis of pulmonary thromboembolism, this diagnostic method is considered to provide important information when deciding on a comprehensive therapeutic strategy for this disease.

Urinary Excretion of Vasoactive Factors following Contrast Media Exposure in Humans

Background: Radiographic contrast media (CM) induce renal vasoconstriction and may initiate induced nephropathy. Endothelin (ET), a vasoconstrictor, and nitric oxide (NO), a vasodilator, which are synthesized in the kidney by the vascular endothelium as well as by tubular epithelial and glomerular mesangial cells, are key modulators of renal circulation after CM administration. Intravascular CM, in addition, induces pronounced diuresis and natriuresis. The aim of the present study was to evaluate and compare changes in endogenous vasoactive mediators and contrast-induced natriuresis after CM administration. Methods: Diagnostic angiographic procedures were performed in 14 patients (9 males and 5 females) using the non-ionic CM Iopamidol. Before and immediately after angiography, venous blood and urine samples were obtained. The urinary excretion of ET-1 and nitrates/nitrites (NOx), and the fractional excretion of sodium (FENa) were measured and analyzed. Results: The urinary excretion of both ET-1 and NOx increased significantly (p < 0.05) after angiography, and urinary ET-1 and NOx excretion was correlated with an increase in FENa (p < 0.05). Conclusion: Exposure to CM in humans is associated with an increase in urinary ET and NOx. The excretion of sodium following CM administration is associated with an increase in urinary ET and NOx. ET and NO might be important in the renal change in humans after CM administration.

Simultaneous assessment of myocardial scar and coronary artery disease by navigator-gated 3D fat-suppressed delayed-enhancement CMR: comparison with 2D delayed-enhancement CMR, CT and CAG

Summary The aim of this study was to assess the feasibility of navigator-gated 3D fat-suppressed delayed-enhancement CMR (DE-CMR) for simultaneous assessment of the myocardial scar and coronary artery disease, by comparing with 2D DE-CMR, CT, and CAG. Background Simultaneous assessment of myocardial scar or perfusion reduction and coronary artery stenosis is currently performed by side-by-side comparison or image fusion using coronary CTA and myocardial perfusion study, but the misregistration and differences in spatial resolution between imaging methods can be problematic. A CMR technique that can visualize both myocardial scar and coronary artery disease during a single examination may resolve this problem. Methods