Asia Oceania Journal of Nuclear Medicine and Biology最新文献

Celiac disease (CD) is a chronic immune-mediated enteropathy that is caused by both environmental (gluten) and genetic (human leukocyte antigen (HLA) and non-HLA genes) factors. Patients may be asymptomatic or exhibit atypical symptoms, necessitating a high index of suspicion for proper diagnosis. The evaluation of CD patients with ¹⁸F-FDG PET/CT imaging can be difficult, owing to the fact that this disease is inflammatory in nature. Typical ¹⁸F-FDG PET/CT gastrointestinal manifestations of celiac disease include increased multifocal or diffuse bowel uptake, whereas single short segmental uptake is rarely encountered; thus, awareness of this wide range of findings is important to guide physicians through proper management and outcome. We report a case of small intestine adenocarcinoma and known CD complaining of recent episodes of diarrhea and weight loss that had a suspicious small bowel wall thickening that corresponds to a short segmental hypermetabolic process on FDG PET/CT follow-up scan. The patient was then referred to the gastroenterology department and underwent a colonoscopy, a biopsy was taken that revealed CD and was negative for malignancy. Furthermore, 6 months later the abovementioned segmental FDG activity was completely resolved without any treatment received at the given time.

Objectives: The purpose of this study was to validate undersampled single-photon emission computed tomography (SPECT) imaging using a combination of compressed sensing (CS) iterative reconstruction (CS-IR) and offset acquisition.

Methods: Three types of numerical phantoms were used to evaluate image quality and quantification derived from CS with offset acquisition. SPECT images were reconstructed using filtered back-projection (FBP), maximum likelihood-expectation maximization (ML-EM), CS-IR, and CS-IR with offset acquisition. The efficacy of CS-IR with offset acquisition was examined in terms of spatial resolution, aspect ratio (ASR), activity concentration linearity, contrast, percent coefficient of variation (%CV), and specific binding ratio (SBR).

Results: The full widths at half maximum remained unchanged as the number of projections decreased in CS-IR with offset acquisition. Changes in ASRs and linearities of count density were observed for ML-EM and CS-IR from undersampled projections. The %CV obtained by CS-IR with offset acquisition was substantially lower than that obtained by ML-EM and CS-IR. There were no significant differences between the %CVs obtained from 60 projections by CS-IR with offset acquisition and from 120 projections by FBP. Although the SBRs for CS-IR with offset acquisition tended to be slightly lower than for FBP, the SBRs for CS-IR with offset acquisition did not change with the number of projections.

Conclusions: CS-IR with offset acquisition can provide good image quality and quantification compared with a commonly used SPECT reconstruction method, especially from undersampled projection data. Our proposed method could shorten overall SPECT acquisition times, which would benefit patients and enable quantification with dynamic SPECT acquisitions.

The kidney is an unconventional site for thyroid metastasis. As of the writing of this article, only about 30 cases have been reported. It presents like a renal mass. We are reporting a man with thyroid carcinoma presenting with distant metastasis to the kidney. He had complaints of abdominal pain and haematuria. Initial imaging suggested a left renal mass. A diagnosis of renal cell carcinoma was made and a nephrectomy was performed. Histopathology revealed it to be a metastasis from cancer of the thyroid gland. Subsequently, an ultrasound of the thyroid gland was performed, which showed a malignant appearing thyroid nodule. Correlative bone scan showed uptake at multiple skeletal sites. Total thyroidectomy was done and it was found to be papillary thyroid cancer. Subsequently, high dose radioactive iodine was administered. The patient was followed up and has recently found to have metastasis to the brain and is undergoing radiotherapy.

Objectives: Somatostatin receptor scintigraphy (SRS) using ¹¹¹In-pentetreotide has no established quantification method. The purpose of this study was to develop a new quantitative method to correct the partial volume effect (PVE) for individual energy peaks in ¹¹¹In-pentetreotide single-photon emission computed tomography (SPECT).

Methods: Phantom experiments were performed to construct a new quantitative method. In the phantom experiments, a NEMA IEC body phantom was used. Acquisition was performed using two energy peaks (171 keV and 245 keV) on the SPECT/CT system. The volume of interest was set at each hot sphere and lung insert in the SPECT images of each energy peak, and the recovery coefficient (RC) was calculated to understand the PVE. A new quantitative index, the indium uptake index (IUI), was calculated using the RC to correct the PVE. The quantitative accuracy of the IUI in the hot sphere was confirmed. Case studies were performed to clarify the quantitative accuracy. In a case study, the relationship between the IUI and the Krenning score, which is used as a visual assessment, was evaluated for each lesion.

Results: The obtained RCs showed that the energy peak at 171 keV was faster in recovering the effect of PVE than that at 245 keV. The IUI in the 17-mm-diameter hot sphere was overestimated by 4.8% and 8.3% at 171 keV and 245 keV, respectively, compared to the actual IUIs. The relationship between IUI and Krenning score was rs=0.773 (p<0.005) at sum, rs=0.739 (p<0.005) at 171 keV, and rs=0.773 (p<0.005) at 245 keV.

Conclusion: We have developed a new quantification method for ¹¹¹In-pentetreotide SPECT/CT using RC-based PVE correction for an individual energy peak of 171 keV. The quantitative accuracy of this method was high even for accumulations of less than 20 mm, and it showed a good relationship with the Krenning score; therefore, the clinical usefulness of IUI was demonstrated.

Objectives: Bacterial endotoxin test (BET) for detection and quantification of endotoxin in radiopharmaceuticals (RPs), used for therapy or diagnosis, is prerequisite to administration in patients. Out of the two established methods used for this purpose (Kinetic Chromogenic Assay: KCM and Gel Clot Bacterial Endotoxin Test: GC-BET), GC-BET is recommended by pharmacopeias to evaluate the interferences exhibited during the assay due to presence of various ingredients in samples. In the present study, the influence of excess of cations in [¹⁷⁷Lu]Lu-DOTATATE, used for Peptide Receptor Radionuclide Therapy (PRRT), were studied and a protocol to negate the enhancement observed was developed. Additionally, a protocol for carrying out GC-BET for extremely viscous [¹³¹I]I-Lipiodol was standardized.

Methods: GC-BET was performed for [¹⁷⁷Lu]Lu-DOTATATE and [¹³¹I]I-Lipiodol at maximum valid dilution (MVD), using LRW as a diluent. To negate the false positivity observed in case of [¹⁷⁷Lu]Lu-DOTATATE, various concentrations of calcium chloride (CaCl₂) were added and evaluated for the reversal of the interference observed initially. To prevail the difficulty in performing GC-BET for [¹³¹I]I-Lipiodol various modification in the protocols like orbital vortexing at different rpm and time intervals were performed. KCM assays were also performed for studied RPs at MVD.

Results: It was observed that at MVD, [¹⁷⁷Lu]Lu-DOTATATE exhibited false positivity in GC-BET. However, all the individual reagents used in labeling of [¹⁷⁷Lu]Lu-DOTATATE did not show any false positivity. Finally, performing the assay with an addition of 2mM CaCl₂ (final concentration) nullified the false positivity. Further, intricacy in performing GC-BET for [¹³¹I]I-Lipiodol due to its viscosity was resolved by orbital vortexing at 3000 rpm for 5 minutes.

Conclusions: Our study proved that false positivity was observed in GC-BET for [¹⁷⁷Lu]Lu-DOTATATE due to the presence excess M³⁺ ions. Further, our study is the first of its kind which demonstrated methods for negating these false positive results by using modified protocol and hypothesizing the reason behind the enhancement. Additionally, ours is the first study which proved that a simple step of vortexing the viscous RPs like [¹³¹I]I-Lipiodol can resolved the problems encountered during performing GC-BET due to viscosity of RPs.

A 53-year-old woman with a plantar malignant melanoma lesion was referred to our tertiary clinic for sentinel lymph node mapping. Lymphoscintigraphy with ^99mTc-Phytate detected ipsilateral inguinal and popliteal sentinel nodes. After total resection of nodes, the pathology report confirmed that all specimens were involved by the tumor. As part of an institutional study evaluating somatostatin receptor avidity of melanoma by ^99mTc-HYNIC-TOC scan, she also underwent a whole-body octreotide scan, which surprisingly showed intense tracer uptake in the right cervical region, confining in SPECT/CT images to a mass at the C2 spinal level, adjacent to the right carotid bifurcation. Neck surgery with gamma probe after injection of another dose of ^99mTc-HYNIC-TOC was performed successfully, and the pathology report was consistent with a carotid body tumor. To best our knowledge, our case is the first one in the literature, which reports an incidental paraganglioma with ^99mTc-HYNIC-TOC scan which resected via radio-guided surgery, again with ^99mTc-HYNIC-TOC tracer.

Objectives: ¹⁸F-FDG PET/CT is increasingly performed in patients with differen-tiated thyroid cancer. The aim of this study was to assess the clinical impact of ¹⁸F-FDG PET/CT on the management of patients with differentiated thyroid carcinoma who had elevated serum thyroglobulin (Tg) and negative ¹³¹I whole body scan (WBS).

Methods: 67 patients with differentiated thyroid carcinoma were included in this study. The findings of ¹⁸F-FDG PET/CT imaging were compared with histo-pathology, follow up imaging, or clinical follow-up results. The diagnostic accuracy of ¹⁸F-FDG PET/CT was evaluated for the entire patient group and for those patients with stimulated serum thyroglobulin levels of less than 5, 5-10, and more than 10 pmol/L as well as for local recurrences and metastases sites. The impact of ¹⁸F-FDG PET/CT on therapeutic management was also evaluated.

Results: 30/67 patients had positive findings on ¹⁸F-FDG PET/CT; 28 were true-positive and 2 were false-positive. ¹⁸F-FDG PET/CT results were true-negative in 36 patients and false-negative in 1 patient. The overall sensitivity, specificity, accuracy, PPV and NPV of ¹⁸F-FDG PET/CT were, 96.5%, 94.5%, 95.5%, 93.3%, and 97.2% respectively. Positive ¹⁸F-FDG PET/CT findings were directly correlated with stimulated serum thyroglobulin levels, 7.1% had Tg between 5-10, and 92.9% had Tg greater than 10 pmol/L. ¹⁸F-FDG PET/CT had a high or moderate impact on treatment management in 28 (41.8%) of patients.

Conclusion: ¹⁸F-FDG PET/CT is able to improve diagnostic accuracy and have management impact in a therapeutically relevant way in patients with differentiated thyroid carcinoma who present with rising thyroglobulin level, negative ¹³¹I WBS, and clinical suspicion of recurrent disease.

Hypercalcemia is a clinical condition characterized by elevated circulating serum calcium levels either due to raised parathyroid hormone in hyperparathyroidism or due to secondary causes of hypercalcemia without elevated parathyroid hormone levels. However, hyperthyroidism may occasionally present with incidentally detected hypercalcemia. We present a case of a 53-year-old woman with a previous history of an underlying thyroid disorder, now presented with features of hypercalcemia and mildly elevated parathyroid hormone levels. Her ultrasonography of the neck was suggestive of an intra-thyroidal parathyroid adenoma and it was localized as a tracer avid lesion within the thyroid gland on dual-phase ^99mTc-sestamibi planar scintigraphy with single photon emission computed tomography/ computed tomography (SPECT/CT). However, a subsequent thyroid profile followed by ^99mTc- pertechnetate thyroid scintigraphy showed a hot nodule in the thyroid gland which changed the diagnosis to a toxic thyroid adenoma. She was treated with radioactive iodine ablation and thyrotoxicosis resolved and the serum calcium levels normalized on her follow-up.

This is a 51-year-old male who presented with abdominal pain, bilateral proximal upper and lower extremities pain and weakness, and decreased urine output with abnormal kidney function test; Urea and creatinine levels were elevated at 231.5 mg/dl and 11.05 mg/dl, respectively. Initial bone scan showed increased uptake within several muscles suspicious for polymyositis, this was confirmed by biopsy of the right triceps, identified by bone scan as the best superficial biopsy site. Pelvis and thigh MRI demonstrated diffuse hyperintense signal on fluid sensitive sequences involving several muscles. Renal biopsy showed acute tubular injury. He was treated with steroids resulting in significant improvement. A repeat bone scan showed near complete resolution of the muscular uptake seen at presentation. This case nicely illustrates the role of bone scanning in the initial recognition and determination of the extent of polymyositis with identification of a suitable biopsy site as well as assessment of response to treatment.

Objectives: The normal range of the frequency of antral contractions, similar to other gastric motility parameters, are different depending on the population and the test meal. We, therefore, conducted the analysis to establish the normal ranges for the frequency of antral contractions derived from dynamic antral scintigraphy (DAS) following an Asian-styled solid meal in Thai healthy volunteers.

Methods: We retrospectively analyzed the data from the study on normal gastric emptying values. The dynamic scintigraphic images had been obtained in a 45 degree left anterior oblique view during the first 32 minutes following the ingestion of a 267-kcal steamed rice, a technetium-99m-labeled microwaved egg and 100 mL of water. A polynomial normalization model was used to analyze and to calculate the frequency of antral contractions. The data analysis was repeated by the same operator 1 month apart to assess reproducibility.

Results: Data of 18 volunteers (10 males and 8 females) were eligible for analysis. The mean±SD of the frequencies of the antral contractions were 3.06±1.08 cycles/min on the first and 3.04±1.10 cycles/min on the second analysis. Comparison of the two analyses revealed a moderate agreement (ICC=0.632, 95% CI 0.329-0.818) without significant difference (p-value=0.942). No significant effect of gender, menstruation status, smoking or age was demonstrated in this study.

Conclusion: DAS is a non-invasive technique that can measure the frequency of antral contractions. The technique is reproducible and consistent. Future study may be required to assess the effect of gender, menstruation status, smoking and age.