Cardiac Magnetic Resonance Versus Single-Photon Emission Computed Tomography for Detecting Coronary Artery Disease and Myocardial Ischemia: Comparison with Coronary Angiography.

BACKGROUND: This study aimed to compare the diagnostic accuracy of stress single-photon emission computed tomography (SPECT) and stress cardiac magnetic resonance (CMR) for the assessment of coronary artery disease (CAD) in the same patients, using coronary angiography as the reference standard. METHODS: Thirty patients with known or suspected CAD who were referred for exercise SPECT myocardial perfusion imaging (MPI) for the evaluation of myocardial ischemia underwent stress CMR MPI and computed tomography coronary angiography (CTCA) or selective coronary angiography (SCA). The data from the two stress modalities were compared against the data from angiography. RESULTS: In our study population, 30% of the recruited subjects had significant CAD. The CMR sensitivity for the detection of significant CAD and/or myocardial ischemia was 89% and specificity was 76%. For SPECT, the corresponding sensitivity was 78% and specificity was 52%. The negative predictive value was 92% for CMR and 83% for SPECT. The receiver-operating characteristic (ROC) analysis evaluating the presence of significant CAD, CMR (area under the curve (AUC) 0.78) outperformed SPECT (AUC 0.59) (p < 0.01). The ROC analysis evaluating the presence of myocardial ischemia was also in favor of CMR (AUC 0.82) versus SPECT (AUC 0.67) (p < 0.01). CONCLUSIONS: CMR has high diagnostic accuracy for the detection of CAD and stress-induced ischemia and appears to outperform SPECT. CMR may thus be the preferred noninvasive imaging modality to assess patients with known or suspected CAD.

Although Non-diagnostic Between Necrosis and Recurrence, FDG PET/CT Assists Management of Brain Tumours After Radiosurgery.

AIM: To re-evaluate the role of (18)F-fluoro-deoxy-D-glucose (FDG) positron emission tomography/ computer assisted tomography (PET/CT) co-registered with magnetic resonance imaging (MRI) in differentiating adverse radiation effect (ARE) from tumour recurrence after Gamma Knife radiosurgery of brain tumours. PATIENTS AND METHODS: Twenty-seven PET/CT studies co-registered with MRI were performed on 16 patients after radiosurgery, with 12/16 patients having multiple radiosurgery treatments. Long term follow-up was used for evaluation, with 3/16 patients being histopathologically confirmed. RESULTS: PET/CT was positive in all studies in 6/16 patients, negative in all studies in 6/16 and changed from negative to positive in one. In 2/16 patients, PET/CT was both positive and negative in separate tumour foci. In 9/16 cases with a positive PET/CT, tumour was confirmed. In 6/16 patients with a negative PET/CT, 3/6 had recurrence and 3/6 ARE. In 1/16, equivocal results became negative after retreatment. PET/CT/MRI identified tumour within ARE. Sensitivity of PET/CT/MRI proved to be 64.7%, and specificity 100%. CONCLUSION: PET/CT/MRI assists management, by revealing metabolism rather than histology.

Imaging of coronary artery bypass grafts by computed tomography coronary angiography.

In recent years, computed tomography coronary angiography is commonly performed as a follow-up examination after coronary artery bypass graft surgery. Coronary grafts owing to their minimal motion are well visualized by computed tomography coronary angiography, allowing radiologists to assess their patency noninvasively with very high diagnostic accuracy. The purpose of this pictorial essay is to provide an excellent overview of the anatomy and findings concerning coronary artery bypass grafts.

Coronary artery anomalies in adults: imaging at dual source CT coronary angiography.

Congenital abnormalities of the coronary arteries have an incidence of 1%, and most of these are benign. However, a small number are associated with myocardial ischaemia and sudden death. Various imaging modalities are available for coronary artery assessment. Recently, multi-detector CT has emerged as an accurate diagnostic tool for defining coronary artery anomalies. The purpose of this pictorial essay is to review the dual source CT appearance of congenital anomalies of the coronary arteries in adults.

Leydig cell tumour of the ovary localised with positron emission tomography/computed tomography.

Androgen-producing ovarian tumours can lead to assessment difficulties because of their small size. We present a case of virilising steroid cell ovarian tumour in a 41-year-old woman localised with Fluorine-18-Deoxyglucose Positron Emission Tomography/Computed Tomography ((18)FDG-PET/CT). Although the biochemical evaluation pointed to an ovarian source of androgen, diagnostic attempts to localise the source of hyperandrogenism with transvaginal ultrasound (US), and magnetic resonance imaging (MRI) of pelvis failed. Additional evaluation with (18)FDG-PET/CT showed an increased uptake in the right ovary. A laparoscopic right oophorectomy was performed and histopathology examination revealed a 1.2-cm Leydig cell tumour. The patient showed regression of clinical signs.

Correlation of radiation dose and heart rate in dual-source computed tomography coronary angiography.

BACKGROUND: Computed tomography coronary angiography (CTCA) has been widely used since the introduction of 64-slice scanners and dual-source CT technology, but the relatively high radiation dose remains a major concern. PURPOSE: To evaluate the relationship between radiation exposure and heart rate (HR), in dual-source CTCA. MATERIAL AND METHODS: Data from 218 CTCA examinations, performed with a dual-source 64-slices scanner, were statistically evaluated. Effective radiation dose, expressed in mSv, was calculated as the product of the dose-length product (DLP) times a conversion coefficient for the chest (mSv = DLPx0.017). Heart rate range and mean heart rate, expressed in beats per minute (bpm) of each individual during CTCA, were also provided by the system. Statistical analysis of effective dose and heart rate data was performed by using Pearson correlation coefficient and two-sample t-test. RESULTS: Mean HR and effective dose were found to have a borderline positive relationship. Individuals with a mean HR >65 bpm observed to receive a statistically significant higher effective dose as compared to those with a mean HR ≤65 bpm. Moreover, a strong correlation between effective dose and variability of HR of more than 20 bpm was observed. CONCLUSION: Dual-source CT scanners are considered to have the capability to provide diagnostic examinations even with high HR and arrhythmias. However, it is desirable to keep the mean heart rate below 65 bpm and heart rate fluctuation less than 20 bpm in order to reduce the radiation exposure.

The impact of FDG-PET/CT on the management of breast cancer patients with elevated tumor markers and negative or equivocal conventional imaging modalities.

OBJECTIVE: To evaluate the clinical impact of fluorodeoxyglucose (FDG)-PET/computed tomography (CT) scan on restaging breast cancer patients with rising tumor markers and negative or equivocal findings in conventional imaging studies. METHODS: We studied 46 patients with breast cancer of an average age of 57.6 years (ranging from 38 to 68 years). All patients were referred for an FDG-PET/CT scan because of elevated tumor markers, without any other obvious clinical or laboratory sign of relapse. Conventional imaging study results were either negative (29 out of 46 patients) or inconclusive (17 out of 46 patients). All patients underwent a whole-body FDG-PET/CT scan in a combined PET/CT. The findings were confirmed by a follow-up at least 9 months later, and when it was possible, final diagnosis was obtained by histopathology. RESULTS: In 34 out of 46 patients, an FDG-PET/CT scan showed sites of increased metabolic activity, indicating active disease. In 23 out of 46 patients, the therapeutic approach and further clinical management were affected. The FDG-PET/CT scan was true-positive in 33 patients, false-positive in one patient, false-negative in five patients, and true-negative in seven patients. On the basis of our results in this population, an FDG-PET/CT scan had a sensitivity of 86.8%, a specificity of 87.5%, and an accuracy of 86.9%. The positive predictive value was 97.1% and the negative predictive value was 58.3%. Clinical management was affected in 50% of these patients. CONCLUSION: The FDG-PET/CT scan plays an important role in restaging breast cancer patients with rising tumor markers and negative or equivocal findings in conventional imaging techniques, with a consequent significant clinical impact on further management in these patients.

Typical cardiac magnetic resonance imaging findings of cardiac amyloidosis.

We report the case of a 62-year-old man who presented with shortness of breath, lower extremity edema and clinical signs of congestive heart failure. Transthoracic echocardiography demonstrated concentric left ventricular hypertrophy with severe diastolic dysfunction and biatrial enlargement. After aggressive diuresis and clinical improvement, a cardiac magnetic resonance imaging (CMR) examination was performed. The study confirmed the presence of concentric left ventricular hypertrophy with borderline systolic function and impaired diastolic function. Delayed contrast-enhanced imaging indicated diffuse enhancement and lack of adequate signal suppression of the left ventricular myocardium, suggesting the diagnosis of infiltrative heart disease. Rectal biopsy confirmed the diagnosis of amyloidosis. This report presents the typical noninvasive imaging findings of cardiac amyloidosis.

Cardiac magnetic resonance detection and typical appearance of microvascular obstruction following myocardial infarction.

We report the case of a 58-year-old man with a recent anterior myocardial infarction, for which he did not receive prompt reperfusion therapy. The patient underwent cardiac magnetic resonance (CMR) imaging, for the assessment of left ventricular function and myocardial viability, and coronary angiography, two weeks after the acute cardiac event. The CMR study demonstrated a moderately dilated left ventricle, with impaired systolic function and wall motion abnormalities in the anterior, apical and inferior left ventricular walls. The T1-weighted images obtained early after contrast administration demonstrated a dark rim in the endocardial region of the interventricular septum and apex. The delayed-enhanced images demonstrated complete absence of signal at the same rim, adjacent to a hyper-enhanced region that corresponded to the wall motion abnormalities. These findings are suggestive of microvascular obstruction in the distribution of the left anterior descending coronary artery. Microvascular obstruction has been reported to correlate positively with the size of the infarction and the left ventricular end-diastolic volume, and inversely with the left ventricular ejection fraction. Furthermore, it has been reported as an independent predictor of future major cardiovascular events. Microvascular obstruction should be routinely checked for in patients presenting in the peri-myocardial infarction period for CMR assessment of myocardial viability.

Clinical experience from 1000 consecutive cardiovascular MRI cases at a tertiary referral medical center.

We present our experience from the first 1000 clinical cardiovascular magnetic resonance imaging cases performed at our institution. The case load included pediatric and adult patients with a male predominance (two thirds of the patient population). The spectrum of diseases was very broad, and included myopathic, atherosclerotic, vascular, valvular, pericardial, neoplasmatic and congenital heart disease. Our experience demonstrates the areas where cardiovascular magnetic resonance imaging has established value and suggests areas of future development.

Negative gallium-67 citrate and positive positron emission tomography/computed tomography spleen scans, in Hodgkin's stage IV lymphoma.

An 18-year-old male patient with Hodgkin's lymphoma stage IVB (HL-IVB), is presented. On a follow-up examination a splenic ultrasound scan showed the presence of multiple intense nodules. The gallium-67 citrate, single photon emission tomography scan was negative, while positron emission tomography/computerized tomography (PET/CT) scan with fluoro-18-fluordeoxyglucose was strongly positive. Massive infiltration of the spleen by HL-IVB tissue was confirmed by pathology after splenectomy. Two successive PET/CT studies for follow-up purposes three and twelve months after completion of chemotherapy, were normal.

Cardiovascular magnetic resonance evaluation of patients with transposition of the great arteries following atrial switch surgical correction.

We present a method of imaging patients with surgically corrected transposition of the great arteries using cardiac magnetic resonance imaging and we describe the findings from a typical case. Cardiac magnetic resonance is superior to other imaging methods for patients with complex congenital heart diseases, both for establishing the initial diagnosis and for subsequent follow-up after surgical therapy.

Relationship of number of phases per cardiac cycle and accuracy of measurement of left ventricular volumes, ejection fraction, and mass.

In cine cardiac magnetic resonance imaging (MRI) studies, for any preset imaging parameters the number of phases per cardiac cycle for a single slice is proportional to breath-hold duration. We investigated the relationship between the accuracy of measurement of left ventricular (LV) end-diastolic and end-systolic volumes (EDV and ESV, respectively), mass and ejection fraction (EF), and the number of phases acquired per cardiac cycle. Twelve adult volunteers underwent cardiac MRI and five complete LV functional studies were obtained with 8, 11, 14, 17, and 20 phases per cardiac cycle. We calculated LV volumes, EF, and mass for each acquisition, and compared them using the 20-phase acquisition as the reference standard. The scan duration was proportional to the number of phases acquired. There was a systematic underestimation of LV, EDV, and EF, with decreasing number of phases. Differences from the reference standard became significant for the 8-phase acquisition (p<0.05). Subgroup analysis showed that only those with slower heart rates (<65/min) had significant differences in EDV, but not in EF, for the 8-phase acquisition. For those with faster heart rates, no differences were detected between the different acquisitions. There were no significant differences between all acquisitions for the LV ESV and mass. We conclude that at least 11 phases per cardiac cycle are needed to maintain accuracy for cine cardiac MRI studies. Decreasing the number of phases per cardiac cycle beyond this cutoff may introduce significant error of measurement, particularly for the left ventricular EDV and EF and especially for those with bradycardia, and should be avoided.