Objectives: The objective is to standardize the reconstruction parameters for the time-of-flight (TOF) versus non-TOF positron-emission tomography/computed tomography (PET/CT) imaging data and validation of the same in a clinical setting. Methods: The four spheres (10.0/13.0/17.0/22.0 mm) of the PET phantom (NEMA IQ Nu 2-2001) were filled with four times higher activity of [¹⁸F]-NaF than the background (5.3kBq/mL). Imaging (image matrix – 128 × 128 × 47, 2 min, 3D model) was done using two different (TOF/non-TOF) PET scanners. Phantom data were reconstructed in TOF and non-TOF modes for lutetium–yttrium oxyorthosilicate and non-TOF mode for bismuth germanate-based PET scanners. The reconstructed data (by varying iteration and subsets) that provided the best image contrast and signal-to-noise ratio (SNR) were evaluated. The whole-body [¹⁸F]-fludeoxyglucose (FDG) PET/CT scans (7–8 frames; 2.0 min/frame) in 16 lymphoma patients were acquired at 60 min after injecting the radioactivity (370.0–444.0 MBq of [¹⁸F]-FDG. The clinical PET/CT data were reconstructed using phantom-derived reconstruction parameters and evaluated for image contrast and SNR of the detected lesions. Results: TOF reconstruction at second iteration provided significantly (P ≤ 0.02) higher SNR (20.7) and contrast (contrast recovery coefficient/background variability = 3.21) for the smallest hot lesions (10.0 mm) in the phantom than the non-TOF system. Similarly, in patient data analysis for the selected FDG avid lesions, the SNR values were significantly (P = 0.02) higher (13.3 ± 6.49) in TOF than (11 ± 6.48) in non-TOF system. Further, the small (≤10.0 mm) lesions were seen more distinctly in TOF system. Conclusion: It is thus observed that TOF reconstruction converged faster than the non-TOF, and the applicability of the same may impact the image quality and interpretation in the clinical PET data. The validation of the phantom-based experimental reconstruction parameters to clinical PET imaging data is highly warranted.

Background: To improve the accuracy of activity image quality, scatter correction is a critical method. The aim of this study is to compare the accuracy in calculation of absorbed dose to patients following radioligand therapy (RLT) with ¹⁷⁷Lu-DKFZ-PSMA-617 by two different methods of background correction in the conjugate view method. Materials and Methods: This study involved 10 patients. The individualized patient dosimetry calculations were based on whole-body planar scintigraphy images acquired in 10 patients with a mean age of 71.4 ± 6.07 years (range 63–85 years) at approximately 0–2 h, 4–6 h, 18–24 h, and 36–48 h after administration of the mean 6253 ± 826.4 MBq (range 5500–7400 MBq) of ¹⁷⁷Lu-DKFZ-PSMA-617. Organ activities were calculated using the conjugate view method by Buijs and conventional background correction. Eventually, the absorbed dose of radiation was calculated using Medical Internal Radiation Dose formalism. Results: The dose per unit of injected activity (mGy/MBq) ± standard deviation for kidney using Buijs and conventional methods was 1.05 ± 0.11 and 0.63 ± 0.14, respectively. Conclusion: The Buijs background correction method was more accurate than the conventional method.

Objective: Spinal cord injury (SCI) extensively impacts the sensorimotor reorganization in the brain. The effects can be both anatomical and functional. To date, not many studies using 18F-Fluoro-2-Deoxyglucose positron emission tomography (18F-FDG PET) to evaluate metabolic changes in the brain are done. Understanding such changes is crucial for developing clinical management and evidence-based rehabilitation strategies for these patients. Subjects and Methods: In this study, we compared 18F-FDG PET imaging of 6 SCI patients with complete paraplegia and 19 controls. Statistical parametric mapping software was utilized to compare the images on a voxel to voxel basis (significance level P < 0.05 and clusters having >50 voxels). Results: The study showed raised metabolism in supplementary motor areas, comprehension centers, some areas in the parietal and temporal lobe, putamen and cerebellum while reduced metabolic uptake in areas like anterior cingulate gyrus, hippocampus and sensory cortical areas when SCI patients were compared against healthy controls. The frontal lobe showed varied results where certain regions showed higher metabolism while the others showed lower in patients compared with controls. Conclusion: Cerebral deafferentation or disuse atrophy can be linked with reduced metabolism while raised uptake can be associated with initiation and planning of movement and cognitive changes in the brain posttrauma.

Objective: Considering the 5α-reductase (5AR) inhibitory activity of the oximes and the importance of the ester group in increasing the anti-androgenic property, we reasoned to synthesize a compound having a lactam group in ring D and an ester group at the 3 β position of the androsterone nucleus. The study aims to radiolabel 17-oxo-17a-aza-D-homo-5-androsten-3β-yl phenoxyacetate (17a-aza steroid) with Tc-99m to evaluate its targeted uptake in experimentally induced prostate carcinogenesis in rats. Materials and Methods: The prediction of the optimal interaction and binding affinity of Tc-99m-17-oxo-17a-aza-D-homo-5-androsten-3 β-ylphenoxyacetate (Tc-99m-17a-aza steroid) toward 5AR inhibitor was done using Biopredicta Vlife MDS tool. Tc-99m-17a-aza steroid was developed by direct radiolabeling protocol. The radio-pharmacological characteristics (serum stability, plasma protein-binding ability, and lipophilicity) of the complex were evaluated. Further, the bio-distribution studies of the complex were performed in rats with experimentally induced prostate carcinogenesis. Results: The in-silico analysis exhibits favorable binding of Tc-99m-17a-aza toward 5AR with D score-130.97. The radiochemical purity of Tc-99m-17a-aza was 96.79%. The radio-complex maintained stability in the rat serum for a period of 6 h (hours). Plasma protein binding and Log Po/w value were observed to be 86.23 ± 7.08% and 0.118 ± 0.045, respectively. A significantly enhanced percent-specific uptake was observed in the prostate of rats with induced prostate carcinogenesis. Conclusion: The study concludes that Tc-99m-17a-aza exhibits prostate specificity and can be explored further for its potential as a radionuclide imaging probe.

Background: Retinoblastoma (RB) is the most common primary intraocular malignancy of childhood. Magnetic resonance imaging (MRI) of the orbit and brain is the preferred imaging modality to diagnose and define extent of disease as well as to assess response to therapy. Sometimes, it may be difficult to differentiate the presence of active residual disease from therapy-related changes based on posttreatment completion MRI. Materials and Methods: RB patients who completed treatment between January 2017 and October 2019 were retrospectively analyzed. We evaluated the utility of F-18-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) to predict active disease in RB patients who continued to have residual disease on MRI at completion of treatment. Results: Out of the 89 patients who completed treatment, dilemma regarding remission status was present in 11 children. All 11 patients underwent FDG-PET-CT. None of them had evidence of metabolically active disease in the orbit, optic nerve, brain, or rest of the body. After a median follow-up of 24 months, no children developed any evidence of disease progression in the form of local or distant relapse. Conclusion: Our results showed that in MRI doubtful cases, a nonavid FDG-PET is reassuring in avoiding further therapy as long as close follow-up can be ensured. FDG-PET-CT may emerge as a useful functional modality to predict disease activity in RB.

Objective: Ex vivo radioactivity measurement of positron emission tomography/computed tomography (PET/CT)-guided biopsy tissue specimen to check the viable tumor sampling and predict the nature of the biopsied lesion. Materials and Methods: We prospectively evaluated the retrieved tissue specimens during PET/CT-guided biopsies for the presence of radioactivity. The qualitative radioactivity was measured by acquiring PET/CT images of the specimen. For quantitative analysis, a multichannel-analyzer (MCA) was used, and a counting-factor (CF) in counts/mCi.mm³ was calculated based on background-corrected net-counts, tissue-volume (mm³), and exponential tracer-activity during biopsy (mCi). The CF-values were compared with the 2-(fluorine-18) fluoro-2-deoxy-D-glucose-avidity in the target lesion and correlated with the histopathology. Results: A total of 49 patients (30 males) aged 51.8 ± 17.8 years were recruited for the biopsy, and radioactivity was measured. All the specimens revealed the presence of radioactivity on PET/CT images of the specimens and MCA counting. The mean CF-values were 17.2 ± 15.6 counts/mCi.mm³. One sample had meager counts with a CF-value of 0.162 and was subjected to re-biopsy after repositioning the coaxial needle to the hypermetabolic site. Pathological diagnosis was established in all the patients (malignancy-29, benign-20). The CF-values were significantly higher in malignant lesions than benign (21.45 ± 18.05 vs. 10.76 ± 8.96 counts/mCi.mm³, P = 0.025). CF-values and maximum standardized uptake value had a significant correlation (Pearson's r = 0.457, P = 0.001). Conclusion: The ex vivo measurement of the radioactivity of retrieved tissue specimens during PET/CT-guided biopsy helps to confirm the sampling from viable region and a highly practical approach to avoid erroneous sampling of a lesion with a large necrotic area. It is also helpful in predicting the nature of the biopsied lesion before the histopathological analysis.

Introduction: Wavelet transforms of an image result in set of wavelet coefficients. Thresholding eliminates insignificant coefficients while retaining the significant ones (resulting in matrix having few nonzero elements that need to be stored). The compressed image is reconstructed by applying inverse wavelet transform. The quality of compressed image deteriorates with increase in compression. Hence, finding optimum value of scale and threshold is a challenging task. The objective of the study was to find the optimum value of scale and threshold for compressing 99mTc-methylene diphosphonate (99 mTc-MDP) bone scan images using Haar wavelet transform. Materials and Methods: Haar wavelet transform at scale 1–8 was applied on 106 99 mTc-MDP whole-body bone scan images, and wavelet coefficients were threshold at 90, 95, 97, and 99 percentiles, followed by inverse wavelet transform to get 3392 compressed images. Nuclear medicine physician (NMP) compared compressed image with its corresponding input to label it as acceptable or unacceptable. The values of scale and threshold that resulted in majority of acceptable images were considered to be optimum. The quality of compressed image was also evaluated using perception image quality evaluator (PIQE) image quality metrics. Compression ratio was calculated by dividing the number of nonzero elements after thresholding wavelet coefficients by the number of nonzero elements in Haar decomposed matrix. Results: NMP found quality of compressed images (obtained at scale 2 and 90 percentile threshold) identical to the quality of the corresponding input images. As per PIQE score, quality of compressed images was perceptually better than that of the corresponding input images. Conclusions: The optimum values of scale and threshold were determined to be 2 and 90 percentiles, respectively.

Struma ovarii is a type of mature ovarian teratoma which accounts for roughly 0.5%–1% (1) of all ovarian tumours and approximately 3% of all ovarian teratomas (2). To be classified as struma ovarii, more than 50% of the tumour must be comprised of thyroid tissue (3). Malignant struma ovarii being rare, no proper guidelines exists regarding its surgical approach or postoperative management. Metastatic malignant struma ovarii, in addition to radical surgery for ovarian mass will require total thyroidectomy to facilitate high dose radioiodine therapy. Here we present the case of a newly married, nulliparous, young lady in her third decade who was diagnosed with malignant struma ovarii with metastatic deposits in fallopian tube and extensive deposits in mesentery and peritoneum., She underwent cryopreservation of embryos followed by bilateral salphingo-oopherectomy + omentectomy + stripping of peritoneum over bladder, abdominal side walls, pelvic peritoneum + appendectomy with preservation of uterus. Total thyroidectomy was done simultaneously. Subsequently she underwent high dose radioiodine therapy. Complete ablation of the residual metastatic deposits were achieved by one sitting of therapy.

Morvan's syndrome (MoS) is a rare, complex neurological disorder characterized by neuromyotonia, neuropsychiatric features, dysautonomia, and neuropathic pain. The majority of MoS cases have a paraneoplastic etiology, most commonly thymoma, usually occurring before the diagnosis of the underlying tumor and showing improvement following surgery. We present a case of 60-year-old patient presenting with suspicious of MoS and autoimmune encephalitis (AE), F-18 fluorodeoxyglucose positron emission tomography/computed tomography as single imaging modality detected and confirmed both AE and thymoma.

Vertebral tuberculosis (TB) is a common form of extrapulmonary TB. Here, the slow-growing Mycobacterium bacillus reaches the disc space through the hematogenous route and leads to various complications. Radiological imaging and histopathology have been the mainstay of diagnosis, but radionuclide imaging techniques using radiolabeled antitubercular drugs have rarely found space in the clinical domain. Here, we present a case of vertebral TB, where a technetium-labeled antitubercular drug, ethambutol, was synthesized and used for imaging the bacteria in vivo. Thus, we demonstrate a rarely used potentially specific agent for tuberculous-infection imaging, which can be produced in-house, and provides rapid results.

Renal transplant (RT) is the preferred treatment modality in patients with end-stage renal disease (ESRD). However, it is associated with a significant rate of complications. Early diagnosis and management of these complications are essential to prevent graft loss. Herein, we describe a case of a 48-year-old male who developed ESRD due to underlying autosomal-dominant polycystic kidney disease and underwent an RT. A routine renal dynamic scintigraphy (RDS) performed on day 4 posttransplant showed a focal minute area of radiotracer accumulation on the delayed static images raising suspicion for urinoma. However, it was deemed normal considering the normal renogram curve and stable clinical condition of the patient. However, on day 9 posttransplant, in view of clinical deterioration marked by decreasing urine output and rising serum creatinine levels, ultrasonography – kidney, ureter, and bladder (USG-KUB) and a repeat RDS were performed. Although the USG-KUB described a peri-nephric fluid collection, the nature of the collection could not be determined. RDS confirmed that the collection was urinoma. On retrospective analysis, the focal area of increased radiotracer uptake corresponded to the site of initial suspicion, although there was an increase in the size of the same. In experienced hands, RDS thus proves to be a highly sensitive tool for the diagnosis of urinoma, much before the clinical complications set in.

Lymphoblastic lymphoma (LBL) is the common non-Hodgkin lymphoma in childhood and adolescence. T-cell LBL (T-LBL) usually manifests with an anterior mediastinal mass and disseminated disease. We present a 12-year-old girl with progressive neck swelling and dyspnea for 1 year. Fluorodeoxyglucose positron-emission tomography/computed tomography done for pretreatment staging unveiled hypermetabolic lymph nodes on both sides of the diaphragm with splenic and bone marrow involvement. Apart from these, there was the extensive involvement of the left pleura. Biopsy and immunohistochemistry revealed T-LBL. The extensive secondary pleural involvement in pediatric T-LBL is rarely seen and needs to be reported.

Healthy men aged 55,39, 23.45 years were administered 18F-fluorodeoxyglucose (¹⁸F-FDG) after fasting for over 5 h; then, a 30-min self-paced walking (6-min walk and 2-min rest + 6-min walk and 2-min rest + 6-min walk and 2-min rest + 6-min walk) session was performed. While walking, the same athletic shoes were used, same with walking supports, flat insoles, and cuboid support insoles (BMZ Inc., Tokyo, Japan). The walking test was performed with eye open. The examination was performed over 30 days apart. ¹⁸F-FDG accumulation within the gastrocnemius muscle was higher, the walking speed was improved. These results suggest that the use of cuboid support insoles may improve the cadence of the lower leg muscles.

Papillary thyroid carcinoma (PTC) is the most frequent type of differentiated thyroid cancers (DTCs) and commonly metastasizes to regional lymph nodes. Distant metastases of DTC typically occur in the lungs and bones. Liver metastases of DTC are very rare and difficult to diagnose. We present a case of a 52-year-old woman who had a previous history of PTC treated by total thyroidectomy and lymph node dissection. The patient received two radioactive iodine-131 (I-131) treatments. The second postradioiodine therapy whole-body scan (WBS) revealed intense iodine uptake in the neck region and in the lungs. After 2 months, during the follow-up period, increase in serum thyroglobulin (Tg) level was detected. Positron-emission tomography–computed tomography (PET-CT) with 18F-fluorodeoxyglucose (FDG) revealed increased FDG uptake in the mass lesion that invaded the muscles in the neck area, lung, bone, and liver. The uptake in liver was interpreted as suspicion of malignancy. The trucut biopsy of the liver masses demonstrated metastases of the thyroid carcinoma with the immunohistochemical thyroid transcription factor-1 and PAX8 positivity observed in these tumor cells. In DTC patients with progressive rapid rise of Tg level, the diagnostic value of I-131 WBS will decrease as the differentiation of the tumor decreases. The combined use of I-131 WBS and FDG PET-CT as diagnostic modalities in these patients will be important in treatment planning in detecting locoregional or distant metastases, especially in patients with negative diagnostic I-131 WBS.

A 53-year-old woman presented with left submandibular gland carcinoma. Contrast-enhanced computerized tomography done for staging revealed suspicious metastatic omental deposit adjacent to left hemi-diaphragm apart from primary and cervical nodal metastasis. Staging F-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography showed high FDG uptake in the primary and metastatic left cervical lymph nodes. However, no FDG uptake was seen in left sub-diaphragmatic mass. Known vascular malformations sites in the left posterior triangle of the neck and liver hemangiomas also showed no uptake. This pattern of uptake raised a suspicion of multiple vascular malformations. Tc-99 m red blood cell scintigraphy was done which confirmed the nature of subdiaphragmatic lesion as haemangioma.

Pyomyositis is an infective involvement of systemic skeletal muscles. We discuss the case of 43-year-old male who presented with quadriparesis, anemia, and hypercalcemia, leading to suspicion of multiple myeloma, and on FDG PET-CT, incidentally, pyomyositis was found. FDG PET-CT thus helped in diagnosing an occult infection which helped in the treatment of the patient.

Fever or pyrexia of unknown origin (PUO) is commonly defined as body temperature higher than 38.3°C on several occasions for a period of at least 3 weeks with uncertain diagnosis after initial routine obligatory investigations. In most cases of PUO, there is an uncommon presentation of a common disease which includes infection, noninfectious inflammatory diseases, malignancy, and miscellaneous causes. We present an interesting case of a 48-year-old man with PUO, who is a known case of multiple myeloma on immunosuppressive therapy, where 18F-fluorodeoxyglucose positron emission tomography-computed tomography was able to detect occult cause of infective etiology.

60-year-old male patient presented with dysphagia and a change in voice for eight months. It was established after Direct laryngoscopy surgery and biopsy, that it was a low-grade B cell non-Hodgkin lymphoma. The primary lesion is resolved with Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, and Prednisolone regimen. Four months later, patient presented with a discharge and maggots at the tracheostomy site. Ifosfamide, Etoposide, Carboplatin was started after a secondary recurrence of disease progression. Hereby we infer this is an unusual case presentation, myiasis with lymphoma recurrence and tough exacting to the otolaryngologist as there are more chances of misdiagnosing as squamous cell carcinoma..

Limbic encephalitis is the inflammation of the medial temporal lobe structures due to direct infectious or indirect autoimmune etiology. Sarcoidosis is a rare cause of limbic encephalitis, has been reported by some authors. Association has also been reported between sarcoidosis, myasthenia gravis, and limbic encephalitis. We report an interesting case of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography demonstrating limbic encephalitis and sarcoidosis in a known case of myasthenia gravis.

Phaeohyphomycosis belongs to a heterogeneous group of fungal infections, originally described by Ajello et al. as mycoses, whose etiologic agents develop in host tissue as dark-walled, septate mycelial elements. Disseminated infections occur in immunocompromised patients, involving the paranasal sinuses, eyes, central nervous system, lymph nodes, and bone. We present here an interesting image of ¹⁸F fluorodeoxyglucose positron-emission tomography/computed tomography showing scapula osteomyelitis caused by phaeohyphomycosis.

Osteochondromas are common benign bone tumors arising from metaphyseal region of long bones. They are notorious for undergoing malignant transformation. We present a case of a middle aged woman with recurrent episodes of swelling in the middle of left 4th finger post excision. Bone scan was performed to look for any malignant transformation of finger lesion and also to rule out skeletal metastases due to recent onset bone pains. 99m Tc MDP (Technetium methylene diphosphonate) bone scan demonstrated a focal hot spot in middle of left 4th finger along the radial side. There was no evidence of skeletal metastases. Surgery is usually curative (70-90%). Limb sparing wide local excision is treatment of choice.