Iranian Journal of Nuclear Medicine
Volume:22 Issue: 2, Summer-Autumn 2014

Bleomycins are DNA-binding biomolecules, which can be used as targeted therapy carriers when labeled with particle-emitters such as Yb-175. In this work the development of Yb-175 bleomycin (175Yb-BLM) has been reported. Yb-175 chloride was obtained by thermal neutron irradiation (3 × 1013 n.cm-2.s-1) of natural Yb2O3 samples at various neutron fluxes and irradiation times. The radionuclide dissolved in acidic media (120mCi/mg) was used in the bleomycin (5 mg) labeling in buffer solution and warming at 60ºC for 48 h. Radiochemical purity was determined by ITLC as well as specific activity calculation followed by stability studies. Biodistribution studies of free Yb-175 and 175Yb-BLM were performed in wild-type mice up to 8 days. At optimized conditions radiochemical purity of 97±0.88 % and specific activity of 1360 MBq/mM was obtained. Biodistribution studies of free Yb-175 demonstrated liver and bone uptake while in case of 175Yb-BLM the target tissues were lung, liver and spleen. 175Yb-BLM complex was prepared at the optimized conditions and suitable characteristics. The accumulation of the radiolabeled compound in lungs, liver and spleen demonstrates a similar pattern to the other radiolabeled bleomycins. Further studies are to be performed for application of this labeled compound in tumor-bearing models.

In the current study we evaluated the incremental value of lateral pelvic lymphoscintigraphy imaging of endometrial or cervical cancer patients who underwent sentinel node mapping. Operable endometrial and cervical cancer patients without clinical or paraclinical evidence of lymph node involvement were included in the study. The day before surgery the patients were sent to the nuclear medicine department for injection of the radiotracer. All patients received two intra-cervical injection of 1 mCi/0.2 cc radiotracer in the 6 and 12 hour locations. 18-24 hours after the radiotracer, lymphoscintigraphy imaging in anterior/posterior and lateral views was done. After induction of anesthesia, 2 mL Methylene blue in two aliquots was injected intra-cervically in the same location as the radiotracers. During operation, any hot and/or blue node was harvested as sentinel nodes. Overall 40 patients were included in the study (30 endometrial and 10 cervical cancers). Sentinel node visualization was achieved in 30 patients. These sentinel nodes were all visualized on the ANT/POST views. Only in 7 patients sentinel nodes could be visualized on the lateral views. Intra-operative sentinel node detection rate was 38 out of 40 (95%). Radiotracer detection rate was 37/40 (92.5%) and blue dye detection rate was 17/40 (42.5%). Anterior/Posterior pelvic lymphoscintigraphy imaging is sufficient for imaging in cervical and endometrial cancer patients undergoing sentinel node mapping. Lateral views can be omitted due to limited valued of these projections.

The main purpose of this study was to compare transient ischemic dilation (TID) ratios in SPECT-low dose CT and SPECT Myocardial Perfusion Imaging (MPI) by application of different quantitative programs and quantify the possible shift in the upper normal limits of TID ratio in the SPECT-CT MPI. 149 Patients with low pre-test probability for coronary artery disease (CAD), based upon Diamond and Forrester method entered the study. Each patient underwent both attenuation correction (AC) SPECT-CT MPI and non attenuation correction (NAC) SPECT MPI (two day Tc-99m sestamibi stress-rest protocol). Normalcy rates were also calculated and compared. The comparison was based on both visual interpretation and quantitative analysis. In the low pre-test probability group visual interpretations lead to a statistically significant improvement in normalcy rate in the SPECT-CT acquisition compared to the SPECT MPI. Regardless of the stress type and software programs used, no significant difference was noted in the upper normal limits of the TID ratios between the AC and NAC acquisitions. The study showed superiority of SPECT-CT MPI to SPECT MPI in terms of normalcy rate. We also propose new upper normal limits of TID ratios for different sets of acquisition-gender-stress modality-software programs.

The selection of optimal treatment of obstructive nephrouropathy requires information about the functional status of each kidney. Nuclear renal scanning objectively measure differential renal function, multiple studies have demonstrated the role of assessment of renal perfusion and GFR with triphasic CT. The aim of this study is to assess the role of CT based on renal parenchymal volume measurement in assessment of individual renal function compared to 99mTc-DTPA renal scan in patients with unilateral renal obstruction. During the indicated time interval, 42 patients with chronic unilateral obstruction; the percentage of the individual renal functions by 99mTc-DTPA and by CT were assessed. The percentage of the individual renal functions as estimated by 99mTc-DTPA in obstructed kidneys ranged from 0% to 40.43% (13.22), while by CT is in range from 0 to 36.68% (15.52). The correlation between percent renal function by 99mTc-DTPA renal scan and percent renal volume by CT were assessed in obstructed kidneys and there were statistically significant relationship (r = 0.877, P < 0.0001). CT scan can be used as an integrated modality to assess the functional and morphological status of unilateral chronic renal obstruction, however 99mTc-DTPA renal scan is a safe choice with less radiation exposure, further comparative studies are needed to assess the role of CT-based parenchymal volume in evaluation of individual renal functions in patients with acute obstruction, bilateral nephropathy and renal impairment.

It is recommended that the physician apply at least a semi-quantitative segmental scoring system in myocardial perfusion SPECT. We aimed to assess the agreement between automated semi-quantitative analysis using QPS (quantitative Perfusion SPECT) software and visual approach for calculation of summed stress score (SSS), summed rest score (SRS) and summed difference score (SDS). We retrospectively studied 1782 consecutive patients who had undergone two-day stress-rest Tc99m-MIBI myocardial perfusion SPECT. Based on 17-segment 5-scale scoring system, SSS, SRS and SDS were calculated visually and using QPS software. There was good correlation between visual analysis and QPS software in calculation of SSS and SRS and a fair correlation for SDS. However, there was statistically significant difference between two methods. By Bland-Altman analyses mean value of the differences (estimated bias) differs significantly from 0 on the basis of 1-sample t-test. Based on bias, Precision and 95% limits of agreement, discrepancies between measurements indicate no agreement equally through the range of measurements, so there is a proportional bias. Based on SSS, SRS and SDS ≤3 and SSS, SRS and SDS >3, there was fair concordance between the visual assessment and automated QPS calculation. Kappa statistics was 0.41 (P<0.001), 0.69 (P<0.001) and 0.25 (P<0.001) for SSS, SRS and SDS respectively. Although semi-quantification sores by visual and automated analysis is correlated, the agreement assessed by Bland-Altman analysis is not high especially in more extensive perfusion defects. Semi-quantitative automated analysis should be used as a supplement to the visual assessment.

Good functional capacity has a high negative predictive value (NPV) in patients with known or suspected coronary artery disease (CAD) similar to a normal gated myocardial perfusion imaging (GMPI). Aim of this study was to evaluate NPV of functional capacity during treadmill exercise in patients with normal GMPI in Pakistani population. This was a prospective study which included 1318 individuals with normal exercise GMPI. On the basis of maximal age predicted heart rate (MAPHR) and metabolic equivalents (METS) achieved, these patient were divided into Group A: ≥ 85% MAPHR and ≥7 METS (714 patients), Group B: ≥85% MAPHR and <7METS (145 patients), Group C: <85% MAPHR and ≥7 METS (289 patients) and Group D: <85% MAPHR and <7 METS (170 patients). Patients were followed up on telephone (15 ±3 months) for fatal or non-fatal myocardial infarction (FMI and NFMI). There was no MI in any group but NFMIs was reported in 2.07% in Group B and 2.35% in Group D. NPV of a normal GMPI in relation with functional capacity was found to be 100% for Group A and C (≥7METS), 97.9% and 97.6% for Group B and D (<7METS) respectively. We conclude that patients with ≥7 METS with normal GMPI had 100% NPV for FMI or NFMIs and omitting GMPI in these patients would save cost and avoid radiation exposure.

The diagnostic accuracy of single photon emission computed tomography (SPECT) is profoundly influenced by attenuation phenomenon. Soft tissue attenuation degrades cardiac SPECT image quality, thereby decreasing the possibility of the detection of the lesions. A variety of correction techniques based on different assumptions have been used to reduce the impact of attenuation. Several types of systems with different transmission hardware modifications and external sources have been developed for clinical implementation. Each system has unique advantages and limitations. In this study, firstly, we introduce the attenuation phenomenon, the problems arising from it and the attenuation correction methods with description of the assumptions related to each of them. The main purpose of this study is to review the developments in the field involving various configurations used for attenuation correction of SPECT images, as tested using either phantom or clinical data, and to delineate an optimal attenuation correction technique by considering the advantages and limitations with each of the configurations.

We report a case of a 75-year old man that came at hematologist’s attention for lymphoma evaluation due to axillary lymph node enlargement and fever. Thorax, abdomen and pelvis Contrast-Enhanced Computed Tomography (CECT) showed lymph nodes, spleen and liver lesions. Axillary lymph node biopsy was performed and the diagnosis of marginal zone lymphoma (MZL) at stage IV was postulated, then the patient was submitted to chemotherapy (CHT) following the R-CVP scheme. After the end of the eighth cycle of CHT he was submitted to a restaging CECT that showed lymph nodes size reduction in all the sites identified on the staging exam. Furthermore the liver lesions disappeared and spleen lesions size was reduced. A whole-body and head 18F-FDG PET/CT was also performed that showed 18F-FDG uptake lesions in right axillary lymph nodes, spleen and liver and the identification of two more extranodal sites, respectively in conjunctiva and skin. Then the necessity of additional CHT cycles and radiotherapy on extranodal sites was postulated. The patient declined the new therapies and unfortunately succumbed four months later. In our case whole body and head 18F-FDG-PET/CT, finding two new extranodal lymphomatous sites and confirming the persistence of the disease, refined and guided the management of the patient suggesting the necessity of additional CHT cycles and radiotherapy on extranodal sites. After histopathological confirmation, a systemic work-up by an oncologist should include whole body and head 18F-FDG-PET/CT to detect possible systemic involvement and guide specific following diagnostic exams.

Metastatic tumors to the heart unlike primary cardiac tumors are not rare. Despite its frequency, cardiac metastasis is commonly detected only during autopsy as the symptoms of disseminated metastasis prevail over symptoms caused by cardiac metastasis and hence is overlooked most of the time. Tumors more commonly found metastasizing to the heart are malignancies of lung, breast, esophagus, lymphoma, leukemia, and malignant melanoma. Head and neck malignancies have a lower incidence of distant metastasis when compared to other malignancies and it rarely causes cardiac metastasis. Here we report the case of a 32 year old Indian male with squamous cell carcinoma of buccal mucosa who underwent surgery followed by chemoradiation. Follow up, FDG PET-CT showed extensive lymphnodal, pulmonary & skeletal metastasis apart from local recurrence in the tongue and floor of mouth. Another discrete foci of increased FDG uptake was noted in the region of heart which corresponded to a hypodense foci in the interventricular septum in contrast enhanced CT raising the possibility of cardiac metastasis. Subsequently, 2D echocardiogram with parasternal long axis view showed hyperdense anterior septum with speckled appearance with a hyperechoic structure attached to the septum towards the right ventricular side confirming metastatic deposit to the heart.