Asia Oceania Journal of Nuclear Medicine and Biology最新文献

Objectives: ¹⁸F-FDG PET/CT has been used to characterize the primary lesion and staging in head and neck cancers (HNC). However, prior studies for detecting distant metastasis and synchronous tumors are sparse, especially in Indian context. To investigate the frequency and distribution of head and neck carcinomas, distant metastases and synchronous malignancies detected in HNC in a north Indian population.

Methods: Medical records and whole body ¹⁸F-FDG PET/CT examinations performed for initial staging on a total of 281 newly diagnosed HNC patients between 01/2019 to 31/6/2023 in North India were retrospectively analyzed and reviewed to look for distant metastasis and synchronous tumors.

Results: On whole body ¹⁸F-FDG PET/CT, distant metastases were detected in 33 (11.7%) patients, all with locally advanced primary tumors corresponding to T category 3 and 4. Lung (6%) and bone (~6.7%) were the most common sites of distant metastasis. In nine patients metastases were detected below the diaphragm. Synchronous malignancies were discovered and histopathologically proven in 22 (7%) patients. Lung carcinoma was the most common synchronous tumor, detected in 9 patients. In seven patients synchronous tumour was detected outside the aerodigestive tract, of which four were below the diaphragm.

Conclusions: Of the distant metastasis diagnosed in 11.7% of HNC patients with TNM tumor category T3 and T4, 3% of metastasis lesions were detected below the diaphragm. Synchronous malignancy was diagnosed in 7% patients irrespective of primary HNC stage. These findings demonstrate the advantage of using whole body ¹⁸F-FDG PET/CT as an ideal and preferred modality for initial staging and screening of HNC patients since detection of distant metastasis or a synchronous malignancy changes the management approach in these patients.

Objectives: Liver malignancies are among the most prevalent causes of cancer-related deaths worldwide. Intra-arterial administration of particulates labeled with beta-emitting radionuclides is one of the non-surgical promising modalities for the treatment of liver cancer.

Methods: In this work, the radiation absorbed dose of ¹⁶⁶Ho-hydroxyapatite (¹⁶⁶Ho-HA) radiopharmaceutical was estimated for adult men based on biodistribution data in normal Wistar rats. The MIRD dose calculation method and the Sparks and Aydogan methodology were applied.

Results: The results show that more than 84% of the absorbed dose is localized in liver tissue (7.35 mGy MBq^-1). Also, radiation absorbed doses of ¹⁶⁶Ho-HA for red bone marrow, osteogenic cells, and spleen tissues were estimated to be about 0.18, 0.38, and 0.24 mGy MBq^-1, respectively. The maximum administrated activity was obtained at 87.5 MBq kg^-1 of body weight with an effective dose of 0.39 mSv MBq^-1. The maximum tolerable dose (MTD) for liver tissue was 6.13 GBq (165.56 mCi).

Conclusion: This study indicated that ¹⁶⁶Ho-HA can provide an impressive dose for liver cancer malignancies with an insignificant dose to healthy tissues.

Tuberculous pericarditis (TBP) is a rare but potentially life-threatening manifestation of tuberculosis, often presenting with nonspecific symptoms and varied clinical features. The disease is characterised by inflammation of the pericardium due to mycobacterium tuberculosis, leading to complications such as effusion, tamponade, and, in chronic cases, constrictive pericarditis. TBP is associated with high mortality, particularly if not promptly diagnosed and treated. ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG PET-CT) has proven invaluable in diagnosing and managing TBP. This imaging modality allows for precise inflammatory activity localisation and differentiates TBP from other causes of pericardial disease. Additionally, the cardiac inflammation protocol of ¹⁸FDG PET-CT enhances imaging accuracy by suppressing the normal physiological FDG uptake in the myocardium. In this case report, we highlight the pivotal role of the cardiac inflammation protocol of ¹⁸FDG PET-CT in both the initial diagnosis and subsequent response assessment of TBP, underscoring its importance in clinical practice.

Objectives: This study aimed to evaluate the quality and associated quantitative values of bone single-photon emission computed tomography (SPECT) with and without SwiftScan using a semiconductor camera equipped with a cadmium-zinc-telluride detector.

Methods: Ten patients with bone metastases from prostate cancer who underwent list-mode SPECT/computed tomography using a whole-body semiconductor camera participated in this study. A total of 130 metastatic lesions from 10 patients were analyzed. Standard SPECT images were obtained approximately 3 h later, and the images were constructed with and without SwiftScan.

Results: The visual assessment of 3-dimensional maximum intensity projection images showed that when an image quality score of 4 (good) or better was considered clinically acceptable, it was maintained at 4 or better in the 75% and 50% scans with SwiftScan, whereas only the 75% scan was considered acceptable without SwiftScan. The intraclass correlation coefficient was 0.952 at 5% for the standard time without SwiftScan and 0.990 with SwiftScan. The maximum standardized uptake value (SUV_max) changes were 0 to 9.5 (median 1.1) at 75%, 0.1 to 11.5 (1.65) at 50%, 0 to 15.7 (2.1) at 25%, 0.1 to 33.2 (4.2) at 10%, 0.2 to 8.9 (5.65) at 5% without SwiftScan. On the contrary, the SUV_max changes in absolute value were 0 to 5.4 (median 0.8) at 75%, 0 to 6.5 (1.4) at 50%, 0 to 19.1 (1.7) at 25%, 0 to 24.2 (2.8) at 10%, 0 to 29.9 (2.6) at 5% with SwiftScan. The contrast-to-noise ratios (CNR) were 95.3 at 75%, 88.3 at 50%, 69.2 at 25%, 45.7 at 10%, and 31.6 at 5% without SwiftScan, and 96.9, 91.7, 78.0, 71.6, and 62.0, respectively, using SwiftScan.

Conclusion: With the use of SwiftScan, a 50% reduction in acquisition time was considered acceptable for image quality with reproducible quantitative indices such as SUV_max and CNR.

Objectives: Brain perfusion single-photon emission computed tomography (SPECT) image quality varies depending on SPECT systems. This study aimed to evaluate the relationship between physical parameters and visual analysis for assessment of the brain SPECT image quality. We conducted our phantom study under various conditions in a multi-center and multi-vendor study.

Methods: SPECT images of the brain phantom were acquired from eight devices in five institutions. The phantom was filled with 28 kBq/ml of ^99mTc solution at the start of scanning. We obtained various data with different acquisition times under clinical reconstruction and acquisition conditions at each institution. Four physical parameters (percent contrast, contrast noise ratio (CNR), asymmetry index (AI), and sharpness index (SI)) were measured with the phantom. Seven observers blindly evaluated all image series and scored them on a scale of 1-3 using four checkpoints: contrast, image noise, symmetry, and sharpness. The average score for all observers was calculated.

Results: CNR increased with increasing visual analysis scores for contrast and image noise, both of which were significantly different between the group with scores "<2" and the group with scores "≥2 and <3". AI decreased as the visual analysis score for symmetry increased, and the AI of both groups with scores "≥2 and <3" and "3" were significantly lower than that of the group with scores "<2". Conversely, no relationship with visual analysis was found for percent contrast and SI.

Conclusion: We clarified the relationship between physical parameters and visual analysis of a brain phantom in a multi-center and multi-vendor study. CNR and AI showed agreement with visual analysis.

Objectives: The phenomenon of peripheral [⁶⁸Ga]DOTATATE avidity without central avidity (which we have termed a "DONUT") has been observed in neuroendocrine neoplasm (NEN) lesions. There has been speculation as to whether this is due to hypoxia, de-differentiated disease or other causes. The presence of hypoxia may have prognostic and therapeutic implications, and was evaluated in these lesions using the PET hypoxia imaging biomarker [¹⁸F]FMISO.

Methods: Prospective pilot study in patients with metastatic NENs with at least one DONUT lesion (central [⁶⁸Ga]DOTATATE non-avidity). [¹⁸F]FDG and [¹⁸F]FMISO scans were acquired within 60 days of the [⁶⁸Ga]DOTATATE PET/CT. [¹⁸F]FMISO scans were acquired as a dynamic scan over 20 mins from injection with a delayed image at 2 hours. The dynamic acquisition was analysed quantitatively using a graphical approach yielding parametric images of Influx Rate Constant and Volume of Distribution. [¹⁸F]FMISO uptake within the identified DONUT hole on the 2 hr delayed scan was qualitatively scored by two experienced nuclear medicine physicians as: 0 (no uptake), 1 (uptake less than normal liver), 2 (uptake equal to normal liver), or 3 (uptake greater than normal liver).

Results: Ten patients were enrolled with primary sites including pancreas (n=3), small bowel (n=3), rectum (n=2), duodenum (n=1) and lung (n=1). Six subjects were scored 1, three subjects were scored 2, and one subject was scored 3. All lesions evaluated were located in the liver. Quantitative [¹⁸F]FMISO parametric imaging showed evidence of increased uptake rate (Ki) in the photopenic areas of the DONUT lesions in 8/10 subjects. Surrounding uptake rate in normal liver was extremely low. In the qualitative delayed image assessment, only one subject demonstrated [¹⁸F]FMISO uptake greater than surrounding normal liver (small bowel primary, G2).

Conclusion: Only one of ten patients with DONUT lesions demonstrated increased [¹⁸F]FMISO uptake rate on delayed static imaging. In contrast, dynamic imaging demonstrated increased [¹⁸F]FMISO uptake rate in the region of [⁶⁸Ga]DOTATATE photopenia on 8 of 10 patients. Future research using [¹⁸F]FMISO in NEN patients should incorporate dynamic imaging.

Breast cancer lymphoscintigraphy is a crucial tool in pre-operative assessment, typically revealing sentinel lymph node drainage patterns within axillary and extra-axillary regions. However, rare cases challenge conventional understanding. We report a 67-year-old woman with breast cancer, where lymphoscintigraphy revealed focal uptake within the falciform ligament of the liver, an exceedingly rare phenomenon. Clinical examination and imaging showed no axillary lymph node involvement. Lymphoscintigraphy and subsequent Single-photon emission computed tomography (SPECT)/computed tomography (CT) uncovered two axillary lymph nodes and an atypical focal uptake in the falciform ligament. Histopathology revealed no metastasis in sentinel nodes. The conventional understanding of breast lymphatic drainage primarily involves axillary and extra-axillary pathways, with the falciform ligament rarely implicated. This case suggests a unique lymphatic pathway connecting the breast and liver, possibly influencing metastasis. Factors such as lymphatic obstruction and valvular incompetency may contribute. This case highlights the importance of comprehensive lymphatic mapping in breast cancer evaluation and underscores the need for further research into atypical lymphatic pathways.

Objectives: To compare the diagnostic performance of [⁶⁸Ga]-Ga-FAPI-46 and [¹⁸F]-FDG PET/CT imaging for the detection of lesions and disease staging in breast cancer.

Methods: Twelve female patients with breast cancer (mean age= 49.2±13.29 years) and previous [¹⁸F]-FDG PET/CT were recruited in the study. [⁶⁸Ga]Ga-FAPI-46 imaging performed in all patients within one month after [¹⁸F]-FDG PET/CT imaging. The acquired PET/CT data with both tracers were reconstructed. Tracer avid lesions with each PET tracer were identified and the semi-quantitative parameters i.e. SUV_max, lesion counts and target-to-background ratio (TBR_max) were analyzed.

Results: Physiologic distribution of [⁶⁸Ga]-Ga-FAPI-46 was observed in the liver, blood pool and kidneys, whereas no tracer uptake was noted in the brain and heart. The mean liver SUV_max for [⁶⁸Ga] Ga-FAPI-46 was 1.5±0.1 which was lower than that noted for [¹⁸F]-FDG PET/CT (2.9±0.2). Likewise, the mean blood pool SUV_max value for [⁶⁸Ga]-Ga-FAPI-46 was lower than [¹⁸F]-FDG PET/CT (1.7±0.1 versus 2.0±0.1). [⁶⁸Ga]-Ga-FAPI-46 PET/CT demonstrated higher tracer uptake in the lesions detected in the brain, bone, internal mammary and lymph nodes in 4/12 patients. The overall lesions detections and the mean SUV_max values did not differ significantly between the two techniques. On the other hand, [⁶⁸Ga]-Ga-FAPI-46 demonstrated higher mean TBR_max than [¹⁸F] FDG PET/CT particularly for lesions detected in kidneys, chest wall, mediastinum, and musculoskeletal lesions. However, both techniques offered identical TNM staging.

Conclusion: The findings of this preliminary study demonstrated that [⁶⁸Ga]-Ga-FAPI-46 and [¹⁸F]-FDG PET/CT offered identical disease staging in the breast cancer patients. [⁶⁸Ga]-Ga-FAPI-46 showed lower liver and blood pool uptake and an enhanced tumor-to-background ratio, thereby suggesting its potential for improved lesions detection. This may open opportunity for emerging FAP based radioligand for therapeutic applications in advanced stage breast cancers. However, this needs validation in a larger number of patients.

Objectives: We investigated image quality and standardized uptake values (SUVs) for different lesion sizes using clinical data generated by ¹⁸F-FDG-prone breast silicon photomultiplier (SiPM)-based positron emission tomography/computed tomography (PET/CT).

Methods: We evaluated the effect of point-spread function (PSF) modeling and Gaussian filtering (Gau) and determined the optimal reconstruction conditions. We compared the signal-to-noise ratio (SNR), contrast, %coefficient of variation (%CV), SUV, and Likert scale score between ordered-subset expectation maximization (OSEM) time-of-flight (TOF) and OSEM+TOF+PSF in phantom and clinical studies. The conventional image was generated with OSEM+TOF_Gau 6 mm. The National Electrical Manufacturers Association body phantom with 10-mm hot sphere data was acquired for 5 min. Twenty-six patients (40 lesions, ranging from 3.7 to 63.0 mm) were examined using prone breast PET/CT with a breast positioner for breast cancer staging. PET data were acquired 125±9.7 min after intravenous injection of 220±16.1 MBq at 5 min/bed.

Results: In the phantom study, a high SNR was obtained from a 3- to 5-mm Gaussian filter for OSEM+TOF+PSF. The contrast obtained with OSEM+TOF without Gaussian filtering was superior to that obtained with OSEM+TOF+PSF_Gau 4 mm. In the clinical study, the image quality depended on lesion size. The average SNR was significantly higher at 40.8% for lesions >20 mm with OSEM+TOF_Gau 6 mm than with OSEM+TOF without Gaussian filtering. The average contrast for lesions ≤10 mm was significantly higher by 42.0% with OSEM+TOF without Gaussian filtering than with OSEM+TOF_Gau 6 mm. The average SUV_max of OSEM+TOF without Gaussian filtering significantly increased by 53.3% for lesions ≤10 mm.

Conclusion: OSEM+TOF without Gaussian filtering provided good contrast and quantitative value for small lesions.

Brain metastasis (BM) occurs only in about 1% of differentiated thyroid carcinoma (DTC) cases. Although DTC generally has a good prognosis, once BM develops, the mortality rate significantly increases up to 78%. BM is usually treated by surgical resection or external radiotherapy, whereas radioactive iodine therapy (RAIT) using I-131 is much less often chosen because BM often shows poor uptake of I-131. In addition, even in case I-131 accumulates in the BM, RAIT could cause adverse effects such as brain hemorrhage and cerebral edema. We present a case of BM from DTC that showed response to I-131 therapy with no severe adverse effects. The brain lesion was very small and asymptomatic, and was only found after a post-therapy I-131 scintigraphy. There are a few case reports where BM was cured by RAIT with little to no side effects. We theorize that BM that is small in size, asymptomatic and show I-131 accumulation could be successfully treated with RAIT.