Optimal Indications of Radioimmunotherapy in Nuclear Medicine: A Mini-Review.

Immunotherapy has emerged as a very considerable and potent therapeutic method in which immune inhibitors have gained a lot of attention in the curative field of various cancers. Under certain circumstances, when radiotherapy is accompanied by immunotherapy, the efficacy of the therapeutic procedure increases. Irradiated tumor cells follow a pathway called immunogenic cell death, which targets tumor associated antigens. The application of radiolabeled antibodies under the concept of "radioimmunotherapy" (RIT) makes the synergistic targeted therapeutic effect possible. Since antibodies themselves are cytotoxic, they can kill the cells that not only bind but are within the path length of their radiation emissions. RIT can be categorized as a substantial progress in nuclear medicine. The main concept of RIT includes targeting specified tumor-expressing antibodies. The mentioned purpose is achievable by formulation of radiolabeled antibodies, which could be injected intravenously or directly into the tumor, as well as compartmentally into a body cavity such as the peritoneum, pleura, or intrathecal space. RIT has demonstrated very optimistic therapeutic outcomes in radioresistant solid tumors. Wide ranges of efforts are accomplished in order to improve clinical trial accomplishments. In this review, we intend to summarize the performed studies on RIT and their importance in medicine.

Segmentation of liver and liver lesions using deep learning.

Segmentation of organs and lesions could be employed for the express purpose of dosimetry in nuclear medicine, assisted image interpretations, and mass image processing studies. Deep leaning created liver and liver lesion segmentation on clinical 3D MRI data has not been fully addressed in previous experiments. To this end, the required data were collected from 128 patients, including their T1w and T2w MRI images, and ground truth labels of the liver and liver lesions were generated. The collection of 110 T1w-T2w MRI image sets was divided, with 94 designated for training and 16 for validation. Furthermore, 18 more datasets were separately allocated for use as hold-out test datasets. The T1w and T2w MRI images were preprocessed into a two-channel format so that they were used as inputs to the deep learning model based on the Isensee 2017 network. To calculate the final Dice coefficient of the network performance on test datasets, the binary average of T1w and T2w predicted images was used. The deep learning model could segment all 18 test cases, with an average Dice coefficient of 88% for the liver and 53% for the liver tumor. Liver segmentation was carried out with rather a high accuracy; this could be achieved for liver dosimetry during systemic or selective radiation therapies as well as for attenuation correction in PET/MRI scanners. Nevertheless, the delineation of liver lesions was not optimal; therefore, tumor detection was not practical by the proposed method on clinical data.

T1 hypointense brain lesions in NMOSD and its relevance with disability: a single institution cross-sectional study.

BACKGROUND: T1 hypointense lesions are considered a surrogate marker of tissue destruction. Although there is a shortage of evidence about T1 hypointense brain lesions, black holes, in patients with Neuromyelitis Optica Spectrum Disorder (NMOSD), the clinical significance of these lesions is not well determined. OBJECTIVES: The impact of T1 hypointense brain lesions on the clinical status and the disability level of patients with NMOSD was sought in this study. METHODS: A total of 83 patients with the final diagnosis of NMOSD were recruited. Aquaporin-4 measures were collected. The expanded disability status scale (EDSS) and MRI studies were also extracted. T1 hypointense and T2/FLAIR hyperintense lesions were investigated. The correlation of MRI findings, AQP-4, and EDSS was assessed. RESULTS: T1 hypointense brain lesions were detected in 22 patients. Mean ± SD EDSS was 3.7 ± 1.5 and significantly higher in patients with brain T1 hypointense lesions than those without them (p-value = 0.01). Noticeably, patients with more than four T1 hypointense lesions had EDSS scores ≥ 4. The presence of T2/FLAIR hyperintense brain lesions correlated with EDSS (3.6 ± 1.6 vs 2.3 ± 1.7; p-value = 0.01). EDSS was similar between those with and without positive AQP-4 (2.7 ± 1.6 vs. 3.2 ± 1.7; p-value = 0.17). Also, positive AQP-4 was not more prevalent in patients with T1 hypointense brain lesions than those without them (50.9 vs 45.4%; p-value = 0.8). CONCLUSION: We demonstrated that the presence of the brain T1-hypointense lesions corresponds to a higher disability level in NMOSD.

FAPI PET/CT provides higher uptake and better target to back ground in recurrent and metastatic tumors of patients with Iodine refractory papillary thyroid cancer compared with FDG PET CT.

PURPOSE: The role of fibroblast activation protein inhibitor (FAPI) PET CT scan is not well documented in papillary thyroid cancer (PTC) patients. Patients with radioiodine refractory PTC and high thyroglobulin levels need PET/CT scan which is generally done by 18F FDG. In the current study, the diagnostic performance of 68Ga FAPI and FDG PET/CT scans were compared head to head in patients with radioiodine refractory PTC. METHOD: Fourteen patients with negative whole body Iodine scans and high thyroglobulin levels underwent whole body PET scans with, respectively, 120-310 and 145-370 MBq 68Ga FAPI-46 and 18F FDG. SUVmax of the back ground in the blood pool and liver and the hottest, largest and average neck, mediastinum, lung and bone lesions were calculated and compared. RESULT: Ten patients had at least one active (SUVmax>blood pool) lesion similarly in two scans. The liver and blood pool SUVmax values were 1.25(0.2) and 1.7(0.2) in FAPI and 2.65(0.2) and 2.0(0.2) in FDG PET images, respectively. The difference was significant (p=0.001). Standard SUV of the hottest lesion to liver was above 3 in all FAPI scans but in half of FDG scans. Target lesion number and intensity were similar between two PET studies but in a patient out of 5 pulmonary metastatic patients, pulmonary nodules were negative (SUVmax=0.9) in FDG while positive (SUVmax= 3.8) in FAPI images (i.e. 20% patient upstaged). CONCLUSION: FAPI accumulates in the recurrent and metastatic lesions of patients with Iodine refractory PTC at least as well as FDG with particular privileges as lower injected activity and lower back ground.

Phantom and clinical evaluation of Block Sequential Regularized Expectation Maximization (BSREM) reconstruction algorithm in 68Ga-PSMA PET-CT studies.

In this study, we aimed to examine the effect of varying ß-values in the block sequential regularized expectation maximization (BSREM) algorithm under differing lesion sizes to determine an optimal penalty factor for clinical application. The National Electrical Manufacturers Association phantom and 15 prostate cancer patients were injected with 68Ga-PSMA and scanned using a GE Discovery IQ PET/CT scanner. Images were reconstructed using ordered subset expectation maximization (OSEM) and BSREM with different ß-values. Then, the background variability (BV), contrast recovery, signal-to-noise ratio, and lung residual error were measured from the phantom data, and the signal-to-background ratio (SBR) and contrast from the clinical data. The increment of BV using a ß-value of 100 was 120.0%, and the decrement of BV using a ß-value of 1000 was 40.5% compared to OSEM. As ß decreased from 1000 to 100, the [Formula: see text] increased by 59.0% for a sphere with a diameter of 10 mm and 26.4% for a sphere with a diameter of 37 mm. Conversely, [Formula: see text] increased by 140.5% and 29.0% in the smallest and largest spheres, respectively. Furthermore, the Δ[Formula: see text] and Δ[Formula: see text] were - 41.1% and - 36.7%, respectively. In the clinical study, OSEM exhibited the lowest SBR and contrast. When the ß-value was reduced from 500 to 100, the SBR and contrast increased by 69.7% and 71.8% in small and 35.6% and 33.0%, respectively, in large lesions. Moreover, the optimal ß-value decreased as lesion size decreased. In conclusion, a ß-value of 400 is optimal for small lesion reconstruction, while ß-values of 600 and 500 are optimal for large lesions in phantom and clinical studies, respectively.

CT radiomics analysis of primary colon cancer patients with or without liver metastases: a correlative study with [18F]FDG PET uptake values.

PURPOSE: Utilizing [18F]Fluoro-2-deoxy-D-glucose Positron Emission Tomography/Computed Tomography ([18F]FDG PET/CT) scans on primary colon cancer (CC) patients including with liver metastases (LM), we aimed to determine the relationship between structural CT radiomic features and metabolic PET standard uptake value (SUV) in these patients. MATERIAL AND METHOD: A retrospective analysis was performed on 60 patients with primary CC, of which 40 had liver metastases that were more than 2 cm in diameter. [18F]FDG PET/CT was used to calculate SUVmax, and 42 CT radiomic characteristics were extracted from non-enhanced CT images. Tumors were manually segmented on fused PET/CT scans by two experienced nuclear medicine physicians. Sixty primary CC and forty LM lesions were segmented accordingly. In the cases of multiple LM lesions, the lesion with the largest diameter was chosen for segmentation. In a univariate analysis approach, we used Spearman correlation with multiple testing correction (Benjamini-Hutchberg false discovery rate (FDR), α = 0.05) to ascertain the relationship between SUVmax and CT radiomic features. RESULT: Twenty-two (52.3%) and twenty-six (61.9%) CT radiomic features were found to be significantly correlated with SUVmax values of primary CC (n = 60) and LM (n = 40) lesions, respectively (FDR-corrected p value < 0.05 and 0.6 < |ρ| < 1). GLCM_homogeneity (ρ = 0.839), GLCM_dissimilarity (ρ = - 0.832), GLZLM_ZLNU (ρ = 0.827), and GLCM_contrast (ρ = - 0.815) were the 4 features most correlated with SUVmax in CC. On the other hand, in LM, the 4 features most correlated with SUVmax were GLRLM_LRHGE (ρ = 0.859), GLRLM_LRE (ρ = 0.859), GLRLM_LRLGE (ρ = 0.857), and GLRLM_RP (ρ = - 0.820). CONCLUSION: We investigated the relationship between SUVmax of preoperative primary CC lesions and their LM with CT radiomic features. We found some CT radiomic features having relationships with the metabolic characteristics of lesions. This work suggests that non-invasive predictive imaging biomarkers for precision medicine can be derived from CT radiomic.

Comparison of myocardial perfusion between the users of two antiepileptic medications: valproate vs. carbamazepine.

Objectives: The prevalence of coronary artery disease (CAD) is high in patients with epilepsy using antiepileptic drugs (AED). Epilepsy, AED, or the type and duration of AED use , may contribute to higher CAD risk.In this study, myocardial perfusion imaging (MPI) was compared between patients using carbamazepine and valproate. Method: Out of 73 patients receiving carbamazepine or valproate monotherapy for more than 2 years, visited at a tertiary referral clinic, 32 patients participated in a 2-day stress and rest phases MPI. For each phase, 15-25 mCi 99mTc-MIBI was injected, at peak exercise or by pharmacologic stimulation for the stress phase. SPECT with cardiac gating was done by a dual-head gamma camera and processed and quantified. Scans with at least one definite reversible hypo-perfusion segment were considered abnormal. Results: Seventeen patients received carbamazepine monotherapy and 15 valproates. Age and duration of AED use were similar between the groups. Two scans were abnormal (6.3%) both in valproate group (13.3%). Duration of AED use was higher in patients with abnormal scans. In patients receiving monotherapy >2 years, the frequency of abnormal MPI was similar between groups (P-value=0.12). In patients receiving monotherapy > 5 years, prevalence of abnormal MPI was higher in the valproate group (28.6% vs. 0.0%; P-value=0.042). Considering valproate subgroup, ischemic patients had higher duration of AED use, comparing with the normal patients (17.0±4.2 vs. 6.4±4.8, P-value=0.014). Conclusion: MPIs were abnormal in patients receiving valproate after 5 years compared to patients receiving carbamazepine. Long-term valproate use may increase the risk of CAD.

Application of Breast Scintigraphy for Patients with Suspicious (Breast Imaging-Reporting and Data System IV) Breast Lesions.

Background: The surgery for a breast imaging-reporting and data system (BIRADS) IV lesions needs imaging or pathology supporting data. The roll of breast scintigraphy for this purpose is unclear. Materials and Methods: In a prospective design, 16 patients with 25 BIRADS IV lesions who were scheduled for surgery were included. Before the surgery, breast scintigraphy was done using a nondedicated dual head gamma camera in the prone position employing a shaped foam pad providing imaging at breast pendulous position. Twenty mCi99m Tc methoxy-isobutyl-isonitrile was injected and two 15 and 60-min delayed imaging were done (anterior, bilateral, and single photon emission computed tomography [SPECT] projections). Pathology reports were collected and tumor to nontumor uptake ratio (T/NT) was analyzed, accordingly. Results: Out of all lesions, 12 were malignant (invasive ductal and lobular carcinoma ductal carcinoma in situ). At 15 min, T/NT was insignificantly higher in the malignant compared to benign lesions (22.8 ± 23.9 vs. 10.1 ± 10.1; P = 0.109). The optimal T/NT cutoff for discrimination of malignant and benign lesions was 20. Only 1 out of 13 benign lesions presented uptake >20 (7.7%; false-positive rate; P = 0.047). The diagnostic accuracy, sensitivity, and specificity for T/NT calculated at 0.68, 0.42, and 0.92, respectively. The T/NT at 60 min remained unchanged for either benign or malignant lesions (22.3 ± 30.2 vs. 11.7 ± 17.1; P = 0.296). Conclusions: Breast scintigraphy with general purpose gamma camera employing SPECT imaging may assist the selection of BIRADS IV lesions in need for surgery. All uptake positive cases should undergo surgery and decision for uptake negative cases should be made based on other data.

Attenuation Correction for Dedicated Cardiac SPECT Imaging Without Using Transmission Data.

Objectives: Attenuation correction (AC) using transmission scanning-like computed tomography (CT) is the standard method to increase the accuracy of cardiac single-photon emission computed tomography (SPECT) images. Recently developed dedicated cardiac SPECT do not support CT, and thus, scans on these systems are vulnerable to attenuation artifacts. This study presented a new method for generating an attenuation map directly from emission data by segmentation of precisely non-rigid registration extended cardiac-torso (XCAT)-digital phantom with cardiac SPECT images. Methods: In-house developed non-rigid registration algorithm automatically aligns the XCAT- phantom with cardiac SPECT image to precisely segment the contour of organs. Pre-defined attenuation coefficients for given photon energies were assigned to generate attenuation maps. The CT-based attenuation maps were used for validation with which cardiac SPECT/CT data of 38 patients were included. Segmental myocardial counts of a 17-segment model from these databases were compared based on the basis of the paired t-test. Results: The mean, and standard deviation of the mean square error and structural similarity index measure of the female stress phase between the proposed attenuation maps and the CT attenuation maps were 6.99±1.23% and 92±2.0%, of the male stress were 6.87±3.8% and 96±1.0%. Proposed attenuation correction and computed tomography based attenuation correction average myocardial perfusion count was significantly higher than that in non-AC in the mid-inferior, mid-lateral, basal-inferior, and lateral regions (p<0.001). Conclusion: The proposed attenuation maps showed good agreement with the CT-based attenuation map. Therefore, it is feasible to enable AC for a dedicated cardiac SPECT or SPECT standalone scanners.

Therapeutic Outcomes of 177Lu-PSMA Targeted Therapy in Patients with Metastatic Castration-Resistant Prostate Cancer: A Single-Center Study.

Objectives: This study aimed to evaluate the therapeutic outcomes of 177Lutetium (177Lu)-PSMA-617 in metastatic castrate-resistant prostate cancer (mCRPC) patients, based on post-treatment imaging findings. Methods: All post-therapeutic scans were collected retrospectively from patients treated with 100-200 mCi 177Lu-PSMA-617 from March 2018 to December 2020 for mCRPC. Two independent readers interpreted the scans and visually categorized them into three strata: responsive, stable, and progressive. The responses were defined based on changes in the number of detected lesions, as well as the intensity of the hottest lesion. Data were registered, and the trend of changes was descriptively discussed. Results: Out of 36 patients (aged 67±8.8 years), 23 underwent at least two treatment cycles. Nineteen patients (82.6%) had bone metastases, 12 (52.2%) had nodal metastases, 5 (21.7%) had liver metastases, and 3 (13.0%) had lung metastases. Eleven patients (47.8%) were considered responsive in the post-therapeutic scans, two of which experienced complete eradication of the metastatic sites. Three patients (13%) were categorized as progressive, and 9 (39.1%) patients remained stable. Regarding mortality, nine patients died during the late follow-up (median of 24 months). In the surviving population, 65% reported no or mild pain in the final follow-up, based on a 5-point scale pain assessment. Conclusion: The treatment of mCRPC patients with 177Lu-PSMA-617 may limit their disease progression and preserve their physical performance, which are important factors in their survival and quality of life.

Poorly differentiated laryngeal neuroendocrine neoplasm with high serum calcitonin level, a case report, with literature review.

Neuroendocrine neoplasm (NEN) of the larynx consists of 0.6% of laryngeal cancer and is the second most common type after squamous cell carcinoma (SCC). Laryngeal NEN rarely secret calcitonin and should be differentiated from medullary thyroid carcinoma. It makes a diagnostic and therapeutic challenge. We describe a case of a laryngeal NEN with calcitonin hypersecretion. A 59-year-old man presented to our clinic with recurrent cough, dysphonia, hoarseness, cervical mass, and significant weight loss. Diagnostic workup showed a supraglottic mass. Biopsy of the lesion revealed large-cell neuroendocrine neoplasm. Further diagnostic workup showed elevated serum calcitonin level. The patient underwent total laryngectomy, thyroidectomy, and modified radical neck dissection. During his follow-up, new subcutaneous nodules appeared that were biopsy-proven metastases. Then adjuvant chemoradiotherapy was performed. Laryngeal NEN with hypersecretion of calcitonin is a rare entity. In patients with elevated serum calcitonin levels and head and neck tumors, it should be considered a differential diagnosis of medullary thyroid carcinoma. As the management and prognosis of these two neoplasms are entirely different.

Generation of18F-FDG PET standard scan images from short scans using cycle-consistent generative adversarial network.

Objective.To improve positron emission tomography (PET) image quality, we aim to generate images of quality comparable to standard scan duration images using short scan duration (1/8 and 1/16 standard scan duration) inputs and assess the generated standard scan duration images quantitative and qualitatively. Also, the effect of training dataset properties (i.e. body mass index (BMI)) on the performance of the model(s) will be explored.Approach.Whole-body PET scans of 42 patients (4118F-FDG and one68Ga-PSMA) scanned with standard radiotracer dosage were included in this study. One18F-FDG patient data was set aside and the remaining 40 patients were split into four subsets of 10 patients with different mean patient BMI. Multiple copies of a developed cycle-GAN network were trained on each subset to predict standard scan images using 1/8 and 1/16 short duration scans. Also, the models' performance was tested on a patient scanned with the68Ga-PSMA radiotracer. Quantitative performance was tested using peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), and normalized root mean squared error (NRMSE) metrics, and two nuclear medicine specialists analyzed images qualitatively.Main results.The developed cycle-GAN model improved the PSNR, SSIM, and NRMSE of the 1/8 and 1/16 short scan duration inputs both18F-FDG and68Ga-PSMA radiotracers. Although, quantitatively PSNR, SSIM, and NRMSE of the 1/16 scan duration level were improved more than 1/8 counterparts, however, the later were qualitatively more appealing. SUVmeanand SUVmaxof the generated images were also indicative of the improvements. The cycle-GAN model was much more capable in terms of image quality improvements and speed than the NLM denoising method. All results proved statistically significant using the paired-sample T-Test statistical test (p-value < 0.05).Significance.Our suggested approach based on cycle-GAN could improve image quality of the 1/8 and 1/16 short scan-duration inputs through noise reduction both quantitively (PSNR, SSIM, NRMSE, SUVmean, and SUVmax) and qualitatively (contrast, noise, and diagnostic capability) to the level comparable to the standard scan-duration counterparts. The cycle-GAN model(s) had a similar performance on the68Ga-PSMA to the18F-FDG images and could improve the images qualitatively and quantitatively but requires more extensive study. Overall, images predicted from 1/8 short scan-duration inputs had the upper hand compared with 1/16 short scan-duration inputs.

Diagnostic Value of Radiolabelled Somatostatin Analogues for Neuroendocrine Tumour Diagnosis: The Benefits and Drawbacks of [64Cu]Cu-DOTA-TOC.

Neuroendocrine tumours (NETs) arise from secondary epithelial cell lines in the gastrointestinal or respiratory system organs. The rate of development of these tumours varies from an indolent to an aggressive course, typically being initially asymptomatic. The identification of these tumours is difficult, particularly because the primary tumour is often small and undetectable by conventional anatomical imaging. Consequently, diagnosis of NETs is complicated and has been a significant challenge until recently. In the last 30 years, the advent of novel nuclear medicine diagnostic procedures has led to a substantial increase in NET detection. Great varieties of exclusive single photon emission computed tomography (SPECT) and positron emission tomography (PET) radiopharmaceuticals for detecting NETs are being applied successfully in clinical settings, including [111In]In-pentetreotide, [99mTc]Tc-HYNIC-TOC/TATE, [68Ga]Ga-DOTA-TATE, and [64Cu]Cu-DOTA-TOC/TATE. Among these tracers for functional imaging, PET radiopharmaceuticals are clearly and substantially superior to planar or SPECT imaging radiopharmaceuticals. The main advantages include higher resolution, better sensitivity and increased lesion-to-background uptake. An advantage of diagnosis with a radiopharmaceutical is the capacity of theranostics to provide concomitant diagnosis and treatment with particulate radionuclides, such as beta and alpha emitters including Lutetium-177 (177Lu) and Actinium-225 (225Ac). Due to these unique challenges involved with diagnosing NETs, various PET tracers have been developed. This review compares the clinical characteristics of radiolabelled somatostatin analogues for NET diagnosis, focusing on the most recently FDA-approved [64Cu]Cu-DOTA-TATE as a state-of-the art NET-PET/CT radiopharmaceutical.

The potential role of the cardiac MIBG scan in differentiating the drug-induced Parkinsonism from Parkinson's disease.

INTRODUCTION: Considering the difficulties of differentiating Parkinson's disease (PD) from drug-induced Parkinsonism (DIP) in patients receiving antipsychotics, developing robust diagnostic tools is essential. Herein, we used the metaiodobenzylguanidine (MIBG) scan to assess its diagnostic accuracy for this purpose. METHODS: 44 DIP patients and 32 patients with PD as controls were enrolled. All the participants underwent a cardiac 131I-MIBG scan. Statistical analysis was conducted to determine the significance of the results, and accuracy analyses were conducted to calculate the related sensitivity and specificity of the MIBG scan. RESULTS: The mean age of PD and DIP groups were 62.6 ± 5.9 and 51.5 ± 10.8 years, respectively. The mean duration of drug consumption in the DIP group was 52.2 ± 29.4 days (the mean interval between drug initiation and DIP onset was 28.5 ± 20.5). Symptoms relief occurred 40 ± 24.2 days after drug discontinuation. In the PD group, 15.6% showed negative and 84.4% positive results on the MIBG scan. In the DIP group, 86.4% were negative, and the remaining were positive. The difference in MIBG uptake between the two groups was statistically significant (P-value < 0.001). The sensitivity and specificity of the MIBG scan were 84.4% (CI: 84.0-84.8) and 86.36% (CI: 86.0-86.7) for the diagnosis of PD, respectively. CONCLUSION: Our results indicated more positive MIBG scans in the PD group than the DIP. Also, the MIBG scan's sensitivity and specificity in differentiating the PD are acceptable. Future works should assess these findings and the role of the MIBG scan in prognosis assessment of DIP and better allocation of the patients to related disciplines.

Ultrasound-Guided Radiofrequency Ablation of Locally Recurrent Thyroid Carcinoma.

INTRODUCTION: We aimed to evaluate the effectiveness and safety of radiofrequency ablation (RFA) for non-surgical treatment of locally recurrent thyroid cancers, in both well-differentiated and medullary thyroid carcinomas (DTC and MTC) that are not amenable to traditional treatments. METHODS: We conducted a retrospective review of 48 patients with 103 recurrent tumors (81 DTC, 22 MTC) who underwent ultrasound-guided RFA. Patients were followed for 12-37 months to observe the outcomes and complications. RESULTS: 64 tumors (62.1%) completely disappeared at the last follow-up visit with 61 (59.2%) being resolved within 12 months. Technical success (volume reduction ratio (VRR) > 50%) was 96% (n = 99) in all tumors. The mean largest diameter of treated tumors decreased from 11.2 ± 5.3 to 2.4 ± 3.4 mm (p value < 0.001), and the mean volume decreased from 501.0 ± 807.0 to 41.6 ± 97.1 mm3 at the last follow-up (mean VRR = 91%). Our patients had a 77.1% recurrence-free survival rate (11 recurrences, 7 DTC, 4 MTC), with an overall mean recurrence-free survival time of 34.6 months (95% confidence interval, 30.0-39.1). We observed 3 cases with complications (voice changes in DTC patients) that completely resolved during follow-ups. CONCLUSION: RFA is a safe and effective alternative to repetitive surgeries in recurrent loco-regional DTCs as well as MTCs. LEVEL OF EVIDENCE: Level 3, Non-randomized controlled cohort/follow-up study.

99m Technetium-HMPAO-labeled platelet scan in practice: Preparation, quality control, and biodistribution studies

Abstract There is no biodistribution or imaging data on 99mtechnetium (Tc)-hexamethyl propylamine oxime (HMPAO)-labeled platelets in the literature. The current study aimed to present updated information about the clinical procedures for preparation and use of labeled platelets. Following two-step centrifugation at 1500 and 2500 rpm, the platelets were extracted from whole blood into platelet-rich plasma (PRP) above the buffy coat and then from PRP into a platelet pellet at the bottom of the tube. The 99mTc-HMPAO-labeled platelets were inspected for purity, viability, release of 99mTc from platelets, and sterility. Also, microscopic examination and thin layer chromatography (TLC) were performed. Biodistribution was assessed following necropsy in BALB/c mice and through imaging of New Zealand rabbits. The separation ratio was estimated at 98%, and radiochemical purity was measured to be 80%. The labeling efficiency was above 30% in more than half of the assays (range: 17-43%). The release of 99mTc from platelets was 9% per hour at 37ºC. After 24 hours, stability was estimated at 54% in the human serum. The target organs of mice included the spleen and liver. In rabbits, the imaging results indicated liver as the target organ. Thyroid uptake was negligible up to 90 minutes. Based on the findings, extraction of platelets and labeling them with 99mTc-HMPAO is a feasible and safe approach in routine practice.

Discordance Between Using Estimated and Measured Glomerular Filtration Rate for Drug Dosing in Kidney Transplant Recipients.

INTRODUCTION: Estimating glomerular filtration rate (eGFR) using different formulas is common clinical practice for evaluating kidney function and drug dosing. But, the performance of available eGFR equations is questionable during early days after kidney transplantation. METHODS: This study compared the performance of three common eGFR equations (Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)) in relation with measured GFR (mGFR) using clearance of Tc-99m-diethylenetriaminepentaacetic acid, 7 to 10 days post kidney transplantation. Agreement of mGFR and different eGFR equations in the staging of kidney function and dosing of 8 common antimicrobials were assessed. RESULT: Thirty kidney and 5 simultaneous pancreas-kidney transplant recipients were included. CG applying total body weight (CGTBW) had the lowest bias (-12 mL/min/ 1.73 m2) and the highest percentage of estimation within 30% of mGFR (71.4%). MDRD showed the best precision (13.14 mL/min/ 1.73m2) and linear correlation with mGFR. CKD-EPI and MDRD acted better than CG for staging the level of kidney function. CGTBW had the lowest discordance rate with mGFR for antimicrobials dosing (33.6%). Discordance rates of drug dosing between mGFR and eGFR formulas were greater for drugs that have higher dosing levels such as (val)-ganciclovir (≥ 54.3%). CONCLUSION: Until developing more accurate methods for estimating kidney function during first 1 to 2 weeks after kidney transplantation, CGTBW method is suggested for drug dose adjustment and MDRD or CKD-EPI equation for the staging of kidney function in these patients, keeping in mind that these formulas underestimate the level of kidney function in new transplant recipients.

Additive value of positron emission tomography/computed tomography scan for detection of aortic tube graft infection: a case report.

BACKGROUND: Diagnosis of aortic graft infection is challenging, and delayed diagnosis is associated with poor prognosis. Positron emission tomography/computed tomography (PET/CT) has improved diagnostic accuracy. CASE SUMMARY: A patient with a history of congenital heart disease was admitted due to fever. He had a history of four cardiac surgeries, including the Bentall procedure for endocarditis. Blood cultures were negative. A semi-mobile mass was detected in the distal portion of the aortic tube graft in echocardiography. PET/CT scan was used to confirm tube graft infection and to support proceeding to cardiac surgery. DISCUSSION: Using multimodality imaging, including PET/CT scan in combination with echocardiography, can improve diagnostic accuracy for the detection of aortic tube graft infection, infection of prosthetic valves, or intra-cardiac devices, especially in high-risk surgical cases.