Iranian Journal of Nuclear Medicine
Volume:32 Issue: 2, Summer-Autumn 2024

In this study, we aimed to evaluate the possibility of assessing cardiac abnormality using the left ventricular anatomical axis (LVAA) obtained from short-axis views of myocardial perfusion imaging (MPI). To obtain LVAA, an ellipse was drawn around the outer wall of SPECT images from XCAT phantoms and patients. The best line was then drawn from the center of all the ellipses in the short-axis views called LVAA. Then, we defined two angles based on LVAA including Ɵ which is the angle created by LVAA with the x-axis, and Φ which is the angle created by LVAA with the z-axis. In this study, 94 cases were enrolled including 48 males (51%) and 46 females (49%) with a mean age of 65.65±10.04. According to the results, there was a significant difference between the two obtained angles and the result of the scan (p<0.05). The ideal cut-off of Ɵ for an abnormal scan was 91.79 (AUC, 0.93; p=0.001) with the sensitivity of 98% and specificity of 80%. It can be concluded that LVAA as a quantitative factor is significantly different between normal and abnormal MPS and can be used for the evaluation of MPI.

Thyroidectomy can be done using different methods. In this study, post thyroidectomy thyroid remnant was compared between tie ligation and LigaSure. Thirty-two patients undergoing thyroidectomy were equally grouped into tie ligation (A) and LigaSure (B). The duration of operation, estimated surgical blood loss, drain discharge, pre and post-operation calcium and parathormone levels, and pre and post-operation subjective assessment of the vocal cord function were collected. Thyroid bed technetium uptake (TTU) and ultra-sonographies were done, respectively, within 3 and 7-14 days after surgery, and thyroid tissue remnant was evaluated. Duration of the operation was longer in group A. Surgery-related blood loss and drain discharge, changes of calcium,  parathormone and quality of voice before and after surgery were similar between the two groups. Three patients had sonographically remarkable post-surgical thyroid remnant; all operated by tie ligation, the difference with group B was insignificant. TTU was similar between groups A and B. Although LigaSure reduces the operation time with similar operation outcomes, the indicators of thyroid tissue surgical remnants are similar between the two sterategies.

The [68Ga]Ga-DOTA-conjugated somatostatin receptor imaging (SR) is becoming the standard imaging procedure in the management of the neuroendocrine tumors (NET). Meanwhile [18F]FDG PET-CT as an adjunctive tool provides useful information in the imaging of NETs. The aim of this study was to compare the diagnostic utility of these imaging methods as well as demonstrate uptake characteristics of NETs. 41 patients (17 M, 21 F; mean: 57.1 years old) with the diagnosis of metastatic neuroendocrine tumors were included in the study. [18F]FDG PET-CT and/or [68Ga]Ga-DOTATATE PET-CT imaging was performed in patients for initial staging, restaging, treatment response evaluation, lesion characterization or to find an unknown primary tumor. The results of the patients were compared with oncologic follow up results and/or pathology results. The size of the lesions were mean: 34 mm and the standardized uptake value in [18F]FDG PET/CT SUVmax(F) and SUV in [68Ga]Ga-DOTATATE PET/CT SUVmax(G) of the lesions were mean: 10.6 and 32.4 respectively. According to the follow up results of the 23 patients with available initial and follow up imaging studies; the management of seven patients were changed (30%). Among the NET group grade 1-3 tumors SUVmax(F) and SUVmax(G) levels were not significantly different. Diagnostic workup of metastatic NET’s should include either or both of the [68Ga] DOTATATE and [18F]FDG PET-CT imaging studies. Individualization of the imaging method of choice in every single patient would be an appropriate approach.

A deep learning pipeline consisting of two deep convolutional neural networks (DeepCNN) was developed, and its capability to differentiate uptake patterns of different radiopharmaceuticals and to further categorize PET images based on the body regions was explored.

We trained two sets of DeepCNN to determine (i) the type of radiopharmaceutical ([18F]FDG and [68Ga]Ga-PSMA) used in imaging (i.e., a binary classification task), and (ii) body region including head and neck, thorax, abdomen, and pelvis (i.e., a 4-class classification task), using the 2D axial slices of PET images. The models were trained and tested for five different scan durations, thus studying different noise levels.

The accuracy of the binary classification models developed for different scan duration levels was 98.9%–99.6%, and for the 4-class classification models in the range of 98.3%–99.9 ([18F]FDG) and 97.8%–99.6% ([68Ga]Ga-PSMA).

We were able to reliably detect the type of radiopharmaceutical used in PET imaging and the body region of the PET images at different scan duration levels. These deep learning (DL) models can be used together as a preliminary input pipeline for the use of models specific to a type of radiopharmaceutical or body region for different applications and for extracting appropriate data from unclassified images.

Prostate-specific membrane antigen (PSMA) is increasingly recognized as a viable target for imaging and therapy of Prostate cancer (PCa). In this study, we introduce the freeze-dried kit formulation of [99mTc]Tc-HYNICALUG for easy clinical evaluation of prostate cancer. In this work, an in silico modeling of the urea-based PSMA small molecule (HYNIC-ALUG) was performed to check its interaction with human glutamate carboxypeptidase II and compared it with experimental results. The HYNIC-PSMA kit was formulated for easy preparation of [99mTc]Tc-HYNIC-ALUG. The kit contained a freeze-dried mixture of HYNIC-ALUG, coligands SnCl2.2H2O, and antioxidant D-mannitol. The calculated Ki value (inhibition/dissociation constant) was 4.55 which showed excellent binding affinity of HYNIC-ALUG with PSMA.  miLogP and cLogS values are -4.04 and -3.07 respectively showing its hydrophilic character and predicting its excellent distribution in biological fluids.  Subsequently, the radiochemical purity of the HYNIC-PSMA kit was 99.1 ± 1.32% (n = 6) determined by radio-ITLC and by HPLC as well. In vitro stability in saline and serum was studied up to 4 h and showed high stability (≥ 96%). The distribution of [99mTc]Tc-HYNIC-ALUG was carried out in two patients and SPECT/CT planar images were acquired at 2h and 4h respectively. Bio-physiological distribution of [99mTc]Tc-HYNIC-ALUG was observed normally in lacrimal, salivary glands, liver, spleen, gut, kidneys, and urinary bladder. The HYNIC-ALUG freeze-dried kit could be used for easy preparation of [99mTc]Tc-HYNIC-ALUG and can be considered as a potential agent for the diagnosis, staging, and restaging of advanced prostate cancer.

Distinguishing the cellular origin of lung cancer is essential for tailored patient care. This pioneering pilot study explores the synergy of 1H-Magnetic Resonance Spectroscopy (1H-MRS) and 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ([18F]FDG PET/CT) in the differentiation of primary squamous cell carcinoma (SCC) of the lung from Hodgkin's lymphoma (HL) metastases. Ethically approved, the study enrolled 21 participants with confirmed lung lesions (10 SCC, 11 HL). [18F]FDG PET/CT and 1H-MRS were conducted, and analyses were performed to assess diagnostic potential. Significant differences in [18F]FDG PET/CT parameters (SUV max BSA, SUV max LBM, and ID%) between SCC and HL were observed. Metabolite concentrations (Cho, Lac, Cr) from 1H-MRS also exhibited distinctions. Correlations between PET values and metabolite concentrations hinted at links between glucose metabolism and molecular composition. This study presents an innovative approach, integrating 1H-MRS and [18F]FDG PET/CT to distinguish primary from metastatic lung lesions. The results hold promise for improving non-invasive diagnostic accuracy and guiding targeted therapies. Future research should validate these findings and explore the potential for clinical integration.

 The early diagnosis of melanoma is crucial for treatment and management of this aggressive malignancy.   The present study describes the preparation and preclinical evaluation of 68Ga-radiolabeled DOTA-4amino-(I-carboxymethyl) piperidine (Pip)-Nle-cysMSHhex peptide ([68Ga]Ga-CCZ01048) as a potential aide for PET imaging and early diagnosis of malignant melanoma.

 Various parameters were assessed to optimize the final preparation processes. The radiochemical purity of the final complex was checked using RTLC and HPLC methods. The stability of the radiolabeled complex was studied at 15, 30, 60 and 120-min post-injection. The partition coefficient was also studied. Cellular studies of the labeled peptide were measured using B16F10 cells at different post-treatment intervals. The biodistribution of the labeled compound was evaluated using normal and tumor-bearing mice.

 [68Ga] Ga-(Pip)-Nle-cysMSHhex radiolabeled complex was prepared with a specific activity of 118.4 TBq/mmol and radiochemical purity > 99% at optimized conditions. The results of stability studies show that the radiolabeled compound is stable in PBS buffer and human serum after 120 min. The cellular studies demonstrated that a binding affinity of [68Ga] Ga-(Pip)-Nle-cysMSHhex on B16F10 cells and the internalization of the complex increased from about 31% in 30 min to 62% in 240 min post-treatment. The biodistribution studies showed excretion of major portion of the tracer through the kidneys. The remainder of the tracer mostly accumulated at the tumor site. No significant uptake in non-target organs was observed at any interval following injection.

 The [68Ga] Ga-(Pip)-Nle-cysMSHhex radiolabeled complex has the potential as a PET imaging agent for evaluation of metastatic malignant melanoma.

Myocardial perfusion imaging (MPI) faces a challenge in diagnostic accuracy due to gastric wall uptake (GWU). Previous studies have linked GWU to proton pump inhibitors (PPIs) intake, but only a minority of patients on PPIs show activity accumulation. Our study aimed to investigate the influence of PPIs on GWU in MPI by single photon emission computed tomography (SPECT) and assess the necessity or benefits of discontinuing PPIs before the procedure. The 368 patients who underwent a two-day stress/rest [99mTc]Tc-MIBI SPECT/CT MPI were divided into three groups: (i) Control group (n=114, without the consumption of any gastroprotective medication), (ii) continued medication(n=48, on PPI treatment) and (iii) discontinued medication (n=206, PPI discontinued for one day or more before MPI). Rest SPECT images were analysed for clinically relevant GWU. Based on our study, out of 114 patients in group (i),16 individuals (14%), and 10 patients from 48 patients in group (ii) (20.8%) demonstrated radioactivity accumulation in the gastric wall. In group (iii) despite discontinuing PPIs use, 20.3% of patients showed GWU. Statistical analysis of these three groups and their subgroups did not show any significant difference in terms of gastric wall uptake of [99mTc]Tc-MIBI in MPI. Concisely, our study found no significant link between PPI use and gastric wall activity in MPI. Further data is needed before adjusting drug guidelines in nuclear medicine centers. Multicenter studies with larger patient cohorts must explore the PPI-GWU relationship, utilizing SPECT/CT scans for precise interference location determination.

Although both asynchronous and synchronous online learning have gained significant popularity in medical education, there have only been a few studies comparing the effectiveness of these two modalities. We compared the exam scores, the proportions of students who scored below the minimal passing levels, and the satisfaction levels of medical students who attended asynchronous online nuclear medicine courses to those who attended synchronous ones. The asynchronous and the synchronous classes were attended by 241 and 268 students, respectively. The median score of the asynchronous class (Median=16, IQR=3) was not significantly different (p=0.859) from that of the synchronous class (Median=15, IQR=3). the percentage of students who scored below the minimum passing level in the asynchronous class (5.60%) was significantly higher (p=0.033) than that of the synchronous class (1.66%). Only 55 students from the asynchronous class (22.8%), and 12 students from the synchronous class (4.48%) returned the satisfaction questionnaires. From the available responses, we did not find significant difference between the satisfaction levels of the two classes.  We found no significant difference in exam scores and satisfaction levels between asynchronous and synchronous online nuclear medicine courses for medical students. However, the asynchronous class had a higher proportion of students scoring below passing levels, which could imply caution needed when implementing online asynchronous teaching methods.

Data acquisition and image reconstruction protocols affect image quality and quantification accuracy in PET imaging. We aimed to standardize and optimize image acquisition, and reconstruction parameter sets using a simultaneous quantitative and qualitative assessment framework for a lutetium oxyorthosilicate (LSO)-based PET/CT scanner. The NEMA IEC Body Phantom acquisition was performed in list mode for 10 minutes with four spheres to background ratios (SBRs). Raw PET data were reconstructed using 60 different protocols. Image quality was evaluated for standardization using contrast, CNR, and noise. Recovery coefficient (RC) measurements were performed for different common VOI definitions. No significant differences were observed between RCs for various acquisition durations. The contrast to noise ratio (CNR) increased at all SBRs by expanding the acquisition duration from 60 to 600 seconds. PET scan time was reduced to 90 seconds per bed position while preserving image quality. Up to 50% improvement in CNR for the highest sub-iteration with a high level of smoothing was observed. PSF-based reconstruction produced a positive bias of RCmax in high SBRs (8 and 10) using higher sub-iterations (30 to 60) with Gaussian filters less than 6 mm FWHM. Moreover, a Sub-iteration of more than 32 with a 4-6 mm FWHM Gaussian filter provides optimized reconstruction sets. Our study demonstrates it would be feasible for PET image acquisition and reconstruction settings to simultaneously allow optimal lesion detection with high image quality while providing accurate quantification.

Blood products including RBC, platelets and plasma are used for the treatment of different diseases, especially in cancer patients. Administration of these derivatives may be associated with a wide range of adverse effects. Transfusion-associated graft-versus-host disease (TA-GVHD) is a fatal complication resulting from blood transfusion. Currently, irradiation of blood products containing cells, which can be achieved using X-ray or gamma ray, represents an optimal approach to prevent TA-GVHD. To the best of our knowledge, this is the first systematic review to address studies conducted to evaluate the effects of gamma irradiation from different sources of 60Co and 137Cs on the laboratory quality of platelets (PCs) and red blood cell concentrates (RBCCs). The results of our review on pre-storage (day 0) gamma irradiation of platelet products (apheresis and PRP) for 7 days of follow-up showed that there was no significant difference between non-irradiated and pre-storage 137Cs-irradiated PCs. In addition, 60Co-irradiated PRP before storage also showed comparable results to their non-irradiated counterparts. Results of our retrospective study on pre-storage (day 0) gamma irradiation of red blood cell concentrates (RBCCs) products for 28 days of follow-up, demonstrated that the viability of CPDA-1-preserved RBCCs appears to be 14 days post-irradiation, while this period for SAGM-preserved RBCCs is up to 21 days. Preservation of irradiated red blood cells in mannitol-containing solutions reduces lipid peroxidation. Overall, the results if our study showed that irradiation time and storage conditions, including preparation methods, anticoagulant/additive solutions, filtration, and washing, affect the quality of transfused blood products.

The coronavirus disease 2019 (COVID-19) pandemic has posed a major challenge to the diagnosis and management of ischemic heart disease (IHD). Myocardial perfusion imaging (MPI) is a non-invasive technique that can assess myocardial ischemia and viability, as well as provide prognostic information for patients with IHD. However, the role of MPI in COVID-19 patients is not well established.

A comprehensive search of PubMed, Embase, Cochrane Library, and Web of Science was conducted to identify relevant studies published until Aprile 24th, 2024. The inclusion criteria were: (1) studies that performed MPI in COVID-19 patients; (2) studies that reported the results of MPI in terms of ischemia, infarction, or perfusion defects; and (3) studies that compared MPI with other diagnostic modalities or clinical outcomes. The quality of the studies was assessed using the QUADAS-2 tool for diagnostic accuracy studies or the ROBIS tool for systematic reviews. A narrative synthesis was performed to summarize the main findings and recommendations.

A total of twenty-two studies met the inclusion criteria. The included study information was categorized into the following aspects: Change in the crude number of MPI scans performed, accidental and definite findings in MPI, and the prognostic outcome of COVID patients who underwent MPI.

During Covid-19 pandemic a reduction in the number of MPI studies was seen. Individuals with a history of COVID-19 infection have higher likelihood of developing ischemic heart disease (IHD). SARS-CoV-2 is an independent risk factor for the development of IHD.

De novo metastatic prostate cancer with neuroendocrine differentiation (NED) at first presentation is extremely rare. A 65-year-old man (Gleason score 5+4, first assumed to be acinar adenocarcinoma), was referred for [99mTc]Tc-HYNIC-PSMA SPECT/CT due to low back pain. The PSA levels were 8 and <0.07 ng/mL at the time of diagnosis and prior to scintigraphy respectively. The scan revealed multiple non-PSMA-avid lesions throughout the skeleton, lung and liver, suggesting the possibility of NED or 2nd malignancy.  Second-look and review of the pathology led to change of the diagnosis to mixed small cell neuroendocrine carcinoma-acinar adenocarcinoma. This case highlights the importance of PSMA imaging in suggestion of type of the tumor which as in our case, might alter the pathologic tissue diagnosis.

An 82-year-old woman with a known chronic small “clot” in the heart presented with rapidly progressive dyspnea. A 2-[18F]fluoro-2-deoxy-D-glucose (2-[18F]FDG) and cardiac-MRI demonstrated rapid enlargement of the right ventricular presumed clot now expanding and obliterating the right ventricular cavity. Patient continued to deteriorate despite urgent cardiac surgery to remove the mass and died 8 days later. Cardiac explant pathology demonstrated phyllodes tumor.

False positive radioiodine uptake may pose difficulties in diagnosis and subsequent management of thyroid cancer. Combined imaging techniques, such as SPECT/CT, play a crucial role in accurately identifying the specific location of radioiodine uptake, thereby avoiding potential diagnostic error. This is particularly important in situations where unexpected uptake could lead to unnecessary treatment interventions such as surgery or radioiodine treatment. In this study, we discuss a case involving a 38-year-old female with a history of thyroid cancer and I-131 treatment. Approximately six years later, her course was complicated by left sided epiphora leading to dacryocystorhinostomy and subsequently elevation of thyroglobulin (Tg) levels prompting retreatment by radioiodine.  The post-therapy whole-body scan revealed false-positive radioiodine uptake on the left side of the skull, conclusively confirmed through SPECT/CT imaging to be localized in the patient's left eye.

Incidental findings in the post-treatment whole body iodine scan (WBIS) sometimes have a broad list of differentials. We present a case of differentiated thyroid carcinoma (DTC), pT3aN1b, with family history of DTC. She was treated with adjuvant 131I therapy (5.55 GBq). The patient's post-treatment WBIS revealed a large, round iodine-avid area above the bladder, which was attributed to a massive uterine fibroid. Physical examination as well as radiologic correlation with SPECT/CT were also concordant. Fibroids can trap the radioiodine by various mechanisms. This case serves as a reminder of an uncommon pitfall in WBIS, particularly in women of reproductive age.

We presented a 2.5-year-old boy with a history of the left pulmonary hypoplasia, repaired congenital diaphragmatic hernia and multiple episodes of pyelonephritis was referred to our department for [99mTc]Tc-DMSA and [99mTc]Tc-EC renal scintigraphy. The scans revealed an unusual pattern of renal uptake with horizontally aligned kidneys located high on left lower thoracic region extended to the mid abdomen. SPECT/CT of the [99mTc]Tc-DMSA scan clearly demonstrated the unusual location of the kidneys which was due to crossed fused renal ectopia and elevated diaphragm. Diuretic renal scans showed no evidence of renal obstruction. Additionally, the VCUG scan indicated vesicoureteral reflux in both ureters.