Nahid Yaghoobi

The diagnosis of patients with fever of unknown origin (FUO) in pediatric heart transplantation is a challenging medical problem. The physician should differentiate between rejections, infections, malignancy, adrenal insufficiency, and drug fever. Immunosuppressive therapy in these patients exposes them to a high risk of developing a post-transplantation fungal infection. In this case, we discuss the diagnostic contribution of the ^99mTc-UBI scan and ¹⁸F-FDG PET scan for diagnosis of fungal infection causing FUO in these patients.

The 18F-FDG PET/CT imaging is a non-invasive modality for diagnosis and staging of metastatic melanoma. Venous thromboembolism (VTE) is a common complication of cancers, which needs anticoagulant therapy. Tumor thrombosis (TT), on the other hand, is an infrequent complication of solid malignancies that may need aggressive management. Accurate diagnosis of TT and its differentiation from VTE may change patient management and avoid unnecessary anticoagulation treatment. The objective of this case is to introduce a patient with malignant melanoma presenting with extensive venous tumor thrombi with intense FDG uptake.

Objective: Myocardial perfusion imaging (MPI) by gated single-photon emission computed tomography (SPECT) is a feasible method in the evaluation of left ventricular perfusion and function. The purpose of this study was to determine the threshold and grading of left ventricular (LV) diastolic dysfunction (LVDD) using gated SPECT MPI. Methods: A total of 149 patients were recruited in the study. All of the patients underwent a standard 2-day stress/rest gated MPI study and transthoracic echocardiography within 2 weeks. The reconstructed rest-only images were analyzed by Cedar-Sinai’s quantitative gated SPECT and the LV diastolic parameters, including peak filling rate (PFR), time to PFR (TTPF) and secondary PFR (PFR2) to PFR ratio were provided and compared to echocardiographic data. Results: 68 (45.6%) and 81 (54.4%) of patients were categorized in LVDD-absent and LVDD-present groups on the basis of LVDD evidence in echocardiography, respectively. receiver-operating-characteristic analysis for PFR and TTPF was performed, resulting in diagnostic sensitivities of 70 and 57% and specificities of 60 and 75% for PFR 160.5 ms, respectively. Applying our previously used thresholds of 208 ms for TTPF and >1 for PFR2/PFR, sensitivities and specificities of 9.9 and 96.6%, 9.9 and 95.6% and 13.8 and 88% were resulted, respectively. Grading of LVDD on the basis of MPI-obtained diastolic parameters showed considerable overlapping data by interquartile range. Conclusion: Gated SPECT MPI can be used as a highly specific means for detection of LV diastolic dysfunction when compared to echocardiography. However, grading of severity of diastolic heart failure appears to be impracticable.

Background: Subdiaphragmatic activity can produce subdiaphragmatic-related artifacts, which can degrade the quality of myocardial perfusion imaging (MPI). Objectives: We examined the impact of drinking milk, water, and lemon juice on different subdiaphragmatic-related artifacts by using ^99mTc-sestamibi myocardial single-photon emission computed tomography (SPECT) in order to determine a feasible method for improving the image quality. Patients and Methods: A total of 179 patients (age 58 ± 9.6 years) were enrolled in this study. The patients were randomly divided into five groups. Ten minutes after injection of 740 MBq 99mTc-sestamibi in both pharmacologic stress and rest phases, the individuals in group 1 were given water and milk (125 mL of each); those in group 2 were given lemon juice (250 mL); group 3 was given milk (250 mL); and group 4 was given water (250 mL), whereas no intervention was performed in group 5. The study was double-blind for both subjects and data collectors. MPI was performed for all patients and image quality was controlled by 2 experienced nuclear physicians. Interfering activity was determined visually on reconstructed images and categorized as extracardiac normalization artifact, overlapping of activity, scattering of activity, and ramp filter artifact. Results: There were significant differences in terms of interfering activity among the five groups; group 3 (milk) had significantly lower interfering activity than other groups had, as defined by overlapping of activity (on both stress and rest images), ramp filter artifact (stress images), and scatter artifact (rest images) (P < 0.05). Furthermore, there was a significant difference in the incidence of good-quality images, with no interfering activity in group 3 in the resting state compared with the other groups in the study (P < 0.05). Conclusions: Drinking 250 mL of milk in either the stress phase or the rest phase of imaging diminishes interfering subdiaphragmatic-related artifacts, particularly overlapping of activity in MPI SPECT, resulting in better-quality images. Keywords: Myocardial Perfusion Imaging; Tomography; Emission Computed; Single Photon; Artifacts

Different techniques have been introduced for full automatic processing of myocardial perfusion imaging with single-photon emission tomography. We tried to evaluate the accuracy of one of these commercial automatic processing methods. The study was performed in 300 patients during 18 months. Two post-stress acquisitions in supine and prone positions and one acquisition at rest , were performed for every patient. All images were processed both automatically and interactively and the results were compared to each other. The automatic method matched the interactive method in 95.22% for left ventricle isolation, in 99.54% for excluding extra-cardiac activity and in 98.22% for reorientation of a single projected data. The automatic method was also successful in complete processing of 81.33% sets of stress (supine)-rest and 79.77% sets of stress (prone)-rest images as compared to the interactive method. In conclusion, the fully automated processing method matches the interactive method in complete processing of myocardial perfusion imaging with single-photon emission tomography more than 79.77% and is of equal accuracy to the interactive method in supine and prone-positioned acquisitions.