Iranian Journal of Nuclear Medicine
Volume:32 Issue: 1, Winter-Spring 2024

Prostate-Specific Membrane Antigen (PSMA) is overexpressed in primary and metastatic prostate carcinoma (PCa) and could be targeted by a [99mTc]Tc-HYNIC-PSMA-11 scan for detection of metastases. Despite extensive studies, data on the most appropriate interval between radiopharmaceutical injection and image acquisition is scarce. We compared the metastasis detection rates of the [99mTc]Tc-HYNIC-PSMA-11 scan between 75-minute and 4-hour intervals of radiopharmaceutical injection. From May 2021 to May 2022, we studied 30 consenting men with pathologically confirmed PCa who were referred to our department requesting  a PSMA scan for primary staging, biochemical recurrence, pre-177Lu-PSMA therapy, or surveillance. 75-minute and 4-hour [99mTc]Tc-HYNIC-PSMA-11 SPECT/CT scan performed following injection of the radiopharmaceutical. The corresponding  metastasis detection rates were evaluated in 75-minute and 4-hour intervals. The mean age of patients was 68.43±9.61 years, with a median PSA of 4.19 ng/ml and a median Gleason Score of 8. Nine cases had negative [99mTc]Tc-HYNIC-PSMA-11 scans, while 21 had positive scans (8 cases with bone, 2 with lung, 4 with lymph node, and 7 with multiple organ metastases). All metastases were detected in both checkpoints, except for one patient, where 75-minute images detected three pelvic metastatic lymph nodes, while four were seen in the 4-hour scan. This small missed right external iliac lymph node did not change the patient’s management. We found no significant difference in the detection rate of metastatic lesions in 75-minute and 4-hour time intervals. These findings could help to decrease  waiting time and  by more efficient scheduling improves patient’s satisfaction at nuclear medicine departments.

The standard treatment for differentiated thyroid carcinoma is post-surgical radioiodine ablation; however, salivary gland damage is prevalent. This study aimed to evaluate the efficacy of Zataria multiflora Boiss. (ZM) aerial part essential oil in protecting salivary glands from post-radioiodine therapy damage in differentiated thyroid cancer patients.

In this randomized clinical trial, 24 patients with differentiated thyroid cancer were randomly allocated to two groups: 11 patients in the ZM essential oil group and 13 in the placebo group. Patients in the intervention and placebo groups received 20 oral drops three times a day of ZM essential oil or placebo respectively, starting from one week before radioiodine therapy to 4 weeks afterward. Salivary gland function was assessed using scintigraphic parameters before and six months following radioiodine therapy.

Follow-up scintigraphy demonstrated significant decrease in parotid UI in the placebo group (P=0.032) while significant increase in UI (P=0.025) and EF (P=0.042) of the parotid was observed in the ZM group. Comparing changes in functional indices of salivary glands between the two groups after six months revealed significantly better function in parotid UI (P=0.005) and parotid EF (P=0.006) in the ZM group. Substantial damage to parotid UI was significantly less in the ZM group (P=0.044).

Results of this study demonstrated that administration of ZM essential oil to patients with differentiated thyroid cancer may protect the salivary glands from radioiodine injury.

Renal cell carcinoma (RCC) is one of the most lethal urologic malignancies. The role of prostate-specific membrane antigen (PSMA) in prostate cancer is well known. PSMA has been shown in other tumors including renal cell carcinoma. [99mTc]Tc-HYNIC-PSMA-11 SPECT/CT is known as a cost effective alternative to [68Ga]Ga-PSMA in prostate cancer. We prospectively evaluated the bio-distribution and diagnostic role of 99mTc-HYNIC-PSMA SPECT/CT in patients with renal tumors before surgery; and also investigated whether the intensity of Tc-PSMA uptake will be different based on tumor histopathology. 14 patients with primary renal tumors, clinically suspicious for RCC, underwent [99mTc]Tc-HYNIC-PSMA-11 SPECT/CT before surgery. All SPECT/CT images were reviewed separately. For quantitative analysis, volume of interest (VOI) was drawn over the tumor as well as the liver and maximum and mean counts were determined. In visual analysis, all renal lesions showed decreased uptake compared to the adjacent parenchymal tissue and liver. Whole body [99mTc]Tc-HYNIC-PSMA-11 scan in all cases could detect the region of tumoral lesion and the size and limits of the tumor were compatible with CT findings and histopathologic results. The ratio of maximum count of the tumor to the mean count of the liver showed no statistically significant difference between different subtypes (P value =0.50); however, the mean value was higher in clear renal cell RCC compared to non-clear cell RCC type (1.40 vs 1.23). In our study, the low and inconsistent uptake of [99mTc]Tc-HYNIC-PSMA-11 in primary tumor of RCC suggest that this radiopharmaceutical is not an ideal agent for imaging this patient population.

Myocardial perfusion imaging (MPI) with pharmacologic stress is a useful technique for evaluation of suspected coronary artery disease (CAD). Heart rate responses (HRR) to vasodilators such as dipyridamole mirror autonomic activity and may provide important prognostic information in CAD patients. In this study, the impact of baseline characteristics of patients including age and gender on the expected HRR has been assessed. This retrospective study included database of 2584 patients (1575 female, 1009 male) who were referred to the nuclear medicine department for pharmacologic MPI. The HRR to dipyridamole was calculated as ratio of maximal heart rate (HR) during or shortly after dipyridamole infusion to baseline HR. The association of HRR with age, gender, presence of other known CAD risk factors and perfusion findings was evaluated. Significant correlation was found between HRR and sex, age, diabetes mellitus (DM), hypertension (HTN), and chronic kidney disease (CKD) (P < 0.001) in both univariate and multivariate analysis. The mean HRR was also significantly higher in patients with normal perfusion on SPECT MPI as compared to patients with abnormal findings, however, multivariate regression analysis showed no significant correlation. In the subgroup of patients with no CAD risk factors, HRR was significantly higher in women under age 55 years. The HRR during dipyridamole infusion depends on age and gender, irrespective of presence of other CAD risk factors and should be considered in the interpretation of. Besides, DM, HTN and CKD are also correlated with lower HRR to dipyridamole stress.

Dopamine transporter (DAT) receptors are reduced in the striatum in dementia of Lewy body (DLB) but normal in Alzheimer’s disease (AD). We assessed the diagnostic accuracy of TRODAT-1 imaging to differentiate patients with DLB from AD. Patients with DLB or AD underwent SPECT TRODAT imaging by [99mTc]Tc-TRODAT-1. Visual interpretation and quantification analyses were done. The activity of the right and left caudate nucleus (CN), putamen (P), striatum (S) as a whole, background (BG), and occipital area (OC) were calculated in addition to the ratio of right and left CN/OC, P/OC, and S/BG. Absolute right and left value difference of the striatum (∆S), putamen (∆P), and caudate (∆CN) to OC or BG were also calculated. The diagnostic accuracy of the visual and quantitative method were compared between patients with AD and LBD. The area under the ROC curve (AUC) was analyzed. Twenty-five patients (15 DLB and 10 AD) were included. Scans were visually interpreted as DLB, AD, and non-diagnostic in 11, 13, and one patients, respectively. Sensitivity, specificity, and accuracy of the scan were 57.1% (28.9-82.3), 70% (34.8-93.3), and 62.5% (40.6-81.2), respectively. CN/OC, P/OC, and S/BG in the left, right, and bilaterally were statistically same between two groups. The AUC of ∆CN/OC was 70.7%.  The optimal cut-off value for ∆CN/BG to diagnose DLB was 6.6% with a sensitivity, specificity, and accuracy, of 86.7%, 50%, and 72.0%, respectively. The [99mTc]Tc-TRODAT-1 imaging has limited diagnostic accuracy for discrimination of DLB and AD patients.

The application of radiotherapy after performing surgery plays a vital role in the breast cancer treatment. In the current study, we investigated the effects of the radiotherapy for breast cancer on pulmonary perfusion scan (PPS) and pulmonary function tests (PFTs). Fifty patients diagnosed with breast cancer with no history of lung diseases who had received radiotherapy after breast surgery and chemotherapy were selected. Mean lung dose (MLD) and volume percentage of the ipsilateral lung receiving a dose equal to or greater than 20 Gy (V20) were calculated for all patients. Quantitative PPS along with SPECT imaging as well as PFTs were performed on each patient before and 6 to 9 months after radiotherapy. For Data analysis, independent Samples t-Test and Pearson's correlation coefficient were used. There were 27 and 23 patients with right and left breast cancer, respectively. In both groups, the relative perfusion of the lung on the radiotherapy side decreased by an average of 5%, which was significant (P-value<0.05). Among 27 patients (54%), lung perfusion defects were observed in the SPECT images. No significant changes were observed between the PFTs before and after radiotherapy (P-value>0.05). No significant relationship was investigated between V20 and mean lung dose (MLD) with relative perfusion of the irradiated lung (P-value>0.05). In this investigation, we demonstrated that quantitative PPS and lung perfusion SPECT were are more reliable than PFTs for evaluating lung following radiotherapy for breast cancer. However, the relative lung perfusion bore no relevancy to V20 and MLD.

This study proposes various designs of partial-ring geometry total-body positron emission tomography (PET) scanners which maintain an extended axial field of view (AFOV) while remaining cost-effective, without sacrificing image quality. The total-body uEXPLORER PET scanner was simulated using the GATE Monte Carlo code.  Partial-ring PET configurations were simulated, reducing the number of detectors by 25% in both the transaxial and axial directions. The sensitivity, noise equivalent count rate (NECR), and image quality of the partial-ring configurations were compared to those of the full-ring configuration. The system sensitivity of partial-ring designs was 0.61 and 0.77 times that of the full-ring detector PET for detector reduction in the axial and transaxial directions, respectively. Notably, despite the higher sensitivity, the 10 mm sphere could not be detected in the transaxial reduction mode. When considering all spheres except the 10 mm one, the mean relative error of contrast recovery (CR) for the same time duration was 2% for detector reduction in the axial direction, whereas it increased to 9% for reduction in the transaxial direction. The results show that reducing the number of detectors in total-body PET scanners can significantly lower manufacturing costs associated with long AFOV PET systems. Although the reduced detector configuration resulted in lower sensitivity, the image quality of the NEMA phantom was found to be superior in the axial reduction mode compared to the transaxial reduction mode. Additionally, the image quality exhibited only a slight difference from that of the full-ring scanner.

The rapid development of artificial intelligence (AI) has sparked a desire to analyse its potential applications in medicine. The aim of this article is to present the effectiveness of the ChatGPT advanced language model in the context of the pass rate of the polish National Specialty Examination (PES) in nuclear medicine. It also aims to identify its strengths and limitations through an in-depth analysis of the issues raised in the exam questions. The PES exam provided by the Centre for Medical Examinations in Łódź, consisting of 120 questions, was used for the study. The questions were asked using the openai.com platform, through which free access to the GPT-3.5 model is available. All questions were classified according to Bloom's taxonomy to determine their complexity and difficulty, and according to two authors' subcategories. To assess the model's confidence in the validity of the answers, each questions was asked five times in independent sessions. ChatGPT achieved 56%, which means it did not pass the exam. The pass rate is 60%. Of the 117 questions asked, 66 were answered correctly. In the percentage of each type and subtype of questions answered correctly, there were no statistically significant differences. Further testing is needed using the questions provided by Centre for Medical Examinations from the nuclear medicine specialty exam to evaluate the utility of the ChatGPT model. This opens the door for further research on upcoming improved versions of the ChatGPT.

Diagnosing Juvenile Idiopathic Arthritis (JIA) presents challenges due to symptom variations, clinical-radiologic delays, and the absence of definitive diagnostic tools. This study aimed to evaluate the diagnostic capability of radiomic features derived from blood pool phase images obtained through bone scintigraphy in JIA. A cohort of 190 patients was included, utilizing the area between knee growth plates as the region of interest (ROI) for extracting image features. After preprocessing, quantitative features were extracted from original and filtered images. A recursive feature elimination (RFE) algorithm identified significant features, subsequently employed in training a random forest classifier. In the validation phase, our radiomic model, comprising 14 features (4 original and 10 filtered image features), achieved an area under the receiver operating characteristic curve (AUC) of 0.89 (95% CI: 0.88–0.92). This robust performance confirmed the efficacy of radiomics in identifying active knee arthritis using technetium–99m-methyl diphosphonate blood pool images in JIA patients. This study highlights the diagnostic accuracy of radiomics in discerning arthritic joints, suggesting its potential as an alternative to conventional quantification techniques. The robustness of radiomics in diagnosing arthritic joints signifies a promising avenue for future research in JIA diagnosis and treatment.

The issue of establishing the diagnosis and differential diagnosis of diabetic foot syndrome (DFS), including at the early stages, is of great relevance, which can be achieved by expanding information on current trends in the visualization of this frequent and severe complication of diabetes mellitus. The authors analyzed, systematized and summarized the modern pilot data on the use of high-tech medical imaging methods in DFS mainly over the past 7 years. An expert analytical assessment of the possibilities of molecular pathogen-specific visualization of pathological processes in DFS using modern methods of SPECT and PET is given. To solve the fundamental and applied aspects of diagnosing DFS, the possibilities of using high-energy radionuclides in bacterial infection were analyzed. The most important literature data of foot perfusion in patients with diabetes mellitus and limb ischemia using new modalities of MRI and hybrid diagnostic methods (SPECT/CT and PET/CT) are systematized, which contributes to a new understanding of the response to revascularization and healing of foot ulcers. This article is aimed at substantiating the multiparametric approach for DFS, as well as the selection, development and implementation of innovative diagnostic strategies in diagnosing DFS and its complications as part of the development of personalized medicine.

Ureteral injuries complicate 0.5-1% of pelvic surgeries in both genders. Diagnosis is usually delayed due to subtle presentation, causing accumulation of urea in the blood and acute renal injury. This prevents physicians from using contrast-based imaging modalities to locate the site of ureteral defect. We aim to reinforce the importance of renal scintigraphy in patients with ureter injury and coexisting renal functional compromise. Two cases of iatrogenic ureter injury and one case of a urinary leak following renal transplantation are presented. All three cases presented with increased creatinine level (due to delayed diagnosis) which made a CT scan, or intravenous pyelogram contraindicated. We used a Technetium-99m-L,L-ethylenedicysteine ([99mTc]Tc-EC) renal scan to locate the site of the ureteral defect without adversely affecting the renal function. In conclusion, [99mTc]Tc-EC is mainly excreted from nephron tubules and can be used in patients with decreased glomerular filtration rate with no additional harm to the kidney including in patients with delayed diagnosis of iatrogenic ureteral defect leading to acute kidney injury (AKI). While the CT scan or IVP was contraindicated, the [99mTc]Tc-EC renal scan located the ureteral defect without compromising kidney function, as [99mTc]Tc-EC is mainly excreted from nephron tubules and can be safely used in patients with AKI.

A 10 years old girl with complain of hematuria and recurrent febrile urinary tract infection (UTI), with a history of bilateral vesicoureteric reflux (VUR) leading to nephrectomy as a result of a non-functional left kidney 3 yrs previously , was referred to our department for diuretic renal scan. The study showed normal function of the right kidney, normal excretion of the tracer from pyelocalyceal (PC) system, along with a small ibsilateral cortical defect. No active renal tissue was noted on the left side. Post void images showed a collection of activity on the left side of the bladder. The SPECT/CT also demonstrated this collection of activity on the same region compatible with post nephrectomy distal ureteral stump. Our case study revealed the diuretic renal scan can be of help in detection of ureterocele in post nephrectomy remained distal ureteral stump which might present with symptoms such as pain and hematuria. In addition our case underscores the importance of SPECT/CT for reaching a correct diagnosis in these patients.

[99mTc]Tc-PYP-RBC is used for the scintigraphy of liver hemangiomas. These images show the incidental detection of portal hypertension caused by vena cava filter obstruction on scintigraphy with [99mTc]Tc-PYP-RBC in a 31-year-old man. The patient was referred to scintigraphy because there was suspicion of liver hemangioma on ultrasound. Scintigraphy showed enlarged and tortuous abdominal veins and a high suspicion of an inferior vena cava filter obstruction was established. The patient was referred to CT where thrombosis of the inserted filter was seen, together with radiological signs of impairment in splanchnic blood flow. Scintigraphy showed signs of an inferior vena cava filter obstruction before the clinical signs were visible.

A bone scan was performed on a 69-year-old man with small cell lung carcinoma (limited stage) following 2nd course of adjuvant chemotherapy using etoposide and cisplatin demonstrating extra-osseous tracer accumulation in the right lower abdominal cavity originally thought to be in the ascending colon, was proven to be an ectopically located gallbladder extending to the right lower quadrant (RLQ). Otherwise, the bone scan did not show abnormal skeletal uptake. The precise reason for gallbladder excretion of [99mTc]Tc-MDP derivatives is unknown. None of the other patients injected with the same [99mTc]Tc-MDP kit demonstrated any gallbladder or other abnormal soft tissue tracer accumulation. In the interpretation of non-osseous uptakes in the right abdominal cavity, ectopic and/or abnormal shaped gallbladder should be taken into consideration.

A 78-year-old woman with metastatic Merkel cell carcinoma (mMCC) to the cervical and thoracoabdominal lymph nodes as well as cutaneous and subcutaneous lesions on the thighs and trunk was referred for peptide receptor radionuclide therapy (PRRT) with [177Lu]Lu-DOTA-TATE. Prior to PRRT, the disease had progressed through four cycles of pembrolizumab. Symptomatic benefit and a stable radiographic response was achieved following two cycles of [177Lu]Lu-DOTA-TATE therapy (cumulative dose: 13.32 GBq) in combination with pembrolizumab. The patient could not receive further cycles due to complications from COVID-19 infection. PRRT in combination with immune checkpoint inhibitors is a promising therapeutic option for mMCC patients, refractory to conventional therapies.