Asia Oceania Journal of Nuclear Medicine & Biology
Volume:8 Issue: 2, Summer and Autumn 2020

I-123-ioflupane single photon emission computed tomography (FP-CIT-SPECT) has been used to assess dopamine transporter (DAT) loss in Parkinson's disease. The specific binding ratio (SBR), a quantitative parameter of DAT density in the striatum, may be affected by differences in age, sex, and SPECT system. The purpose of this study was to evaluate the utility of FP-CIT-SPECT using the Japanese normal database (NDB) in the diagnosis of Parkinson's disease. To standardize the quantitative outcome measures of DAT density obtained with different SPECT systems, striatal phantoms filled with striatal to background materials at ratios between 8:1 and 1:1 were measured using a gamma camera (ECAM) in our institute. Consecutive fifty patients (23 men and 27 women; age range, 40-86 years) with suspected PD undergoing FP-CIT SPECT brain imaging during the period from April to October 2016 were enrolled in this retrospective study. Their final diagnoses were PD in 28 patients and PD in 22 patients. SBRs of the patients were calculated using either new (Japanese database with different age and sex; NEWver) or old (non-Japanese database not specifying age and sex; OLDver) version software (AZE Virtual Place Hayabusa [DaTView], AZE, Ltd. Tokyo, Japan). The McNemar test was used to compare the diagnostic accuracy between old and new versions. Based on the phantom study, the calibrated SBR could be calculated by Y=1.25×Measured SBR+0.78. The sensitivities for OLDver and NEWver were 100% and 93%, respectively (p=0.5), and the specificities were 55% and 100% (p=0.002). The diagnostic accuracy of NEWver (96%) was better than that of OLDver (80%, p<0.001).  FP-CIT-SPECT using the Japanese NDB improved the diagnostic accuracy of PD by improving specificity.

L-4-borono-2-18F-fluoro-phenylalanine (L-[18F]FBPA), a substrate of L-type amino acid transporter 1 (LAT1), is a tumor-specific probe used in positron emission tomography (PET). On the other hand, it has not been examined whether another isomer D-[18F]FBPA accumulates specifically in the tumor. Here, we compared the accumulation of D-[18F]FBPA in C6 glioma and inflammation to evaluate the performance of D-[18F]FBPA as a tumor-specific probe. HEK293-LAT1 and HEK293-LAT2 cells were tested for [14C]-leucine or [14C]-alanine transport, and IC50 values of L- and D-FBPA were evaluated in both cell types. PET was conducted in rat xenograft model of C6 glioma with LAT1 expression and model of turpentine oil-induced subcutaneous inflammation (n=10 for both models). The concentrations of D-[18F]FBPA were compared between glioma and inflammatory lesion using standardized uptake value (SUV). In contrast to L-FBPA, which inhibited substrate uptake in both HEK293-LAT1 and -LAT2 cells, D-FBPA showed no inhibitory effect on both cells, suggesting low transporter selectivity of D-[18F]FBPA against LAT1 and LAT2. Static PET analysis showed low accumulation of D-[18F]FBPA in C6 glioma and inflammatory lesion (SUVmax=0.80±0.16, 0.56±0.09, respectively). Although there was a statistical difference in SUVmax between these tissues, it was difficult to distinguish glioma from inflammation on the PET image due to its low uptake level. Therefore, it was suggested that D-[18F]FBPA is not a suitable tumor-specific probe for oncology PET in contrast to L-[18F]FBPA. This study demonstrated that D-[18F]FBPA is not a LAT1-specific PET probe and shows low uptake in C6 glioma, indicating its unsuitability as a tumor diagnosis PET probe.

Somatostatin receptor-positive neuroendocrine tumors have been targeted using various peptide analogs radiolabeled with therapeutic radionuclides for years. The better biomedical properties of radioantagonists as higher tumor uptake make these radioligands more attractive than agonists for somatostatin receptor-targeted radionuclide therapy. In this study, we tried to evaluate the efficiency of Luthetium-177 (177Lu) radiolabeled DOTA-Peptide 2 (177Lu-DOTA-Peptide 2) as a new radioantagonist in HT-29 human colorectal cancer in vitro and in vivo. DOTA conjugated antagonistic peptide with the sequence of p-Cl-Phe-Cyclo(D-Cys-L-BzThi-D-Aph-Lys-Thr-Cys)-D-Tyr-NH2 (DOTA-Peptide 2) was labeled with 177Lu. In vitro assays (saturation binding assay and internalization test) and animal biodistribution were performed in human colon adenocarcinoma cells (HT-29) and HT-29 tumor-bearing nude mice. 177Lu-DOTA-Peptide 2 showed high stability in acetate buffer and human plasma (>97%). Antagonistic property of 177Lu-DOTA-Peptide 2 was confirmed by low internalization in HT-29 cells (<5%). The desired dissociation constant (Kd =11.14 nM) and effective tumor uptake (10.89 percentage of injected dose per gram of tumor) showed high binding affinity of 177Lu-DOTA-Peptide 2 to somatostatin receptors.  177Lu-DOTA-Peptide 2 demonstrated selective and high binding affinity to somatostatin receptors overexpressed on the surface of HT-29 cancer cells, which could make this radiopeptide suitable for somatostatin receptor-targeted radionuclide therapy.

Nuclear medicine technologists in Japan often perform additional single-photon emission computed tomography (SPECT) with or without computed tomography (CT) after whole-body imaging for bone scintigraphy. In this study, we wanted to identify the bone scanning protocols used in Japan, together with the current clinical practices. The study was conducted between October and December 2017. We created a web survey that was hosted by the Japanese Society of Radiological Technology. The questionnaire included 12 items regarding the demographics of the responders, their scan protocols, and the imaging added to, or omitted from, routine protocols. In total, 228 eligible responses were collected from participants with a mean of 11.6±8.4 years’ experience in nuclear medicine examination. All responders reported using routine scan protocols that included whole-body imaging. However, only 2%, 4%, 20%, and 14% of the responders also acquired single-field SPECT, single-field SPECT/CT, multi-field SPECT, and multi-field SPECT/CT, respectively.  Our survey results indicate that nuclear medicine practice in Japan is beginning to shift from planar whole-body imaging with additional spot planar images to additional SPECT or SPECT/CT. Further study is required to examine the optimal protocols for bone scintigraphy.

The aims of this study were to: 1) discover location (by city) of contributors to poster and oral presentations at recent ANZSNM conferences; 2) determine the nuclear medicine themes most commonly explored; 3) establish institutions producing the highest number of oral and poster abstracts and 4) determine publication rates of conference abstracts to full papers from recent ANZSNM conferences.

Retrospective analysis of abstracts published in the Internal Medicine Journal Special Issues 2014–2019 identified 614 abstracts. Invited plenary speaker abstracts were excluded. Descriptive statistics were used in data analysis. Conference abstracts were analysed using the following criteria: poster or oral presentation, author/s, city location, hospital and subject matter. Themes defined by the ANZSNM conference committee for abstract submission were: cardiology, oncology, neurology, therapy, renal/urology, gastrointestinal, paediatrics, musculoskeletal, infection/inflammation, technology, physics, radiation safety, radiopharmacy/radiochemistry, education, or general. Retrospective analysis of 555 conference abstracts (excluding New Zealand and International, 59 abstracts) using Google Scholar, Pubmed and Google databases was undertaken. Abstract titles, key words, institutions and/or authors’ names were used to find peer-reviewed papers. Identified papers were authenticated through either open access, publicly available author information or Monash University’s library access. Published paper citations were also recorded (up to 1st July 2019).

Analysis of 614 abstracts 2014 – 2019 was performed. Over five years, the average number of poster abstracts was 67.8 and oral 55.0. Sydney submitted the highest number of poster abstracts, while Melbourne the highest number of oral abstracts. Most popular abstract theme was oncology for both poster and oral abstracts. Publications found had in excess of 1250 citations.One hundred and one publications from one hundred and seven conference presentations were identified, distributed across sixty journals. Conference presentation to full publication rate was 18.2%; excluding 2019 conference abstracts the rate was 21.5%.

Publishing research findings is a challenging process. A retrospective analysis of research presented at recent ANZSNM conferences by abstract content was undertaken, with conference presentation to full publication rate found to be at the lower end of reported literature findings.

We present the case of a 60-year-old man with metastatic neuroendocrine tumor of the ileum following ileal resection, being evaluated for 177Lu-based peptide receptor radionuclide therapy. 68Ga-DOTANOC PET/CT showed focal increased tracer uptake in the scrotal region without any morphologic changes on the corresponding CT images. Similar increased tracer uptake was seen on post-therapy whole-body imaging following 177Lu-DOTATATE therapy. An USG guided FNA revealed no malignant cells on cytopathologic examination. This case illustrates that focal testicular tracer uptake, may not always be pathological and can represent a normal physiologic variant, similar to the diffuse testicular somatostatin receptor expression as previously reported in literature.

68Ga Prostate-specific membrane antigen (PSMA) is an increasingly popular radiopharmaceutical tracer in prostate cancer and is becoming increasingly researched in other cancers such as breast cancer, renal cell carcinoma, glioblastoma multiforme, among others. Cholangiocarcinoma is the second most common primary hepatic malignant tumor; it is an aggressive tumor with a 5-year survival rate of less than 5 %. We herein report a case of primary cholangiocarcinoma detected on 68Ga-PSMA PET-CT conducted as part of follow up for prostate cancer and confirmed by biopsy and immunohistochemistry.

Bladder herniation is an uncommon condition mimicking suspicious metastasis on PET/CT imaging. We report a 67 y/o man with prostate cancer referred for recurrence evaluation with 68Ga-PSMA-11 PET/CT. The scan showed an asymmetric site of intense tracer accumulation in the left inguino-scrotal region with the same SUVmax to the pelvic bladder. Reviewing cross sectional CT images with PET confirmed the inguino-scrotal bladder herniation.

Evaluation of calcified metastatic lesions by conventional imaging can be challenging. Ovarian cancer metastases can present with calcification which might increase in size and number following therapy. It is not entirely clear whether these calcifications are associated with tumor response or disease progression. Calcified lesions which do not change in size or configuration are particularly problematic when assessed by RECIST criteria. Positron emission tomography (PET)/computed tomography (CT) is of particular value as it demonstrates the metabolic activity of the calcified lesions, in addition, it might reveal metastases in unexpected sites. We report a case of serous papillary ovarian cancer with extensive abdomino-pelvic calcified metastases referred for evaluation of therapy response. Despite being reported as stable disease on CT evaluation, we observed increased metabolic activity in the calcified lesions both on CT-attenuation corrected and non-attenuation corrected images, which was indicative of inadequate response to therapy. PET/CT is an ideal modality in follow-up of patients with ovarian cancer presenting with calcified metastatic tumoral deposits.

Peritoneal lymphomatosis is an extremely rare presentation of lymphoma. Due to its relative low frequency, it receives much less attention than peritoneal carcinomatosis. The challenge is to differentiate between lymphomatosis and carcinomatosis, as well as peritoneal tuberculosis or other pathologic entities within the peritoneal cavity based essentially on radiologic features. 18F-FDG PET/CT is the main imaging modality for staging and monitoring response to treatment in lymphoma. Peritoneal lymphomatosis is most often associated to aggressive histological subtypes of high-grade lymphoma which are reputed high FDG uptake.   We report two cases of Burkitt’s lymphoma and diffuse large B cell lymphoma (DLBCL), with intense FDG uptake involving the entire peritoneum and decreased FDG activity of the rest of the body including brain and kidneys, giving it an appearance of “peritoneal super scan”, follow up FDG PET/CT showed the disappearance of the peritoneal lymphomatosis and the reappearance of cerebral and urinary activity synonym of complete metabolic response.

Sinus Tarsi Syndrome is a cause of chronic ankle instability and pain. MRI of the ankle has been the modality of choice for diagnosing the condition. However, SPECT-CT offers an alternate modality for diagnosing and evaluation of the condition. We present the case of a footballer who was suffering from chronic right leg pain despite receiving physiotherapy. He was being managed as a case of a chronic ankle sprain. Meanwhile, he was referred to the department as radiology for MRI of the ankle could not be performed as the patient felt claustrophobic. The patient subsequently underwent a 99mTc-MDP Bone scan. He was diagnosed to be suffering from sinus tarsi syndrome as it showed a characteristic pattern noted on 99mTc-MDP Bone scintigraphy. This case report reveals the potential of SPECT-CT as an alternative in the evaluation of chronic ankle sprain to MRI in segment of cases where MRI is not performed due to various reasons.

Chylopericardium is an uncommon and benign condition in which triglyceride-containing chylous fluid collects in the pericardial cavity at high concentrations. Usually, chylopericardium occurs due to congenital malformation of lymphatic vessels or secondary to any trauma, surgeries, neoplasms, etc. However, if exact aetiology cannot be identified, the condition is referred to as Idiopathic chylopericardium which is a very rare presentation in day-to-day clinical practice. General physical examination, routine blood investigations and various anatomical imaging modalities may give a clue in the diagnosis, however, diagnosis can be challenging as they have a variable presentation. Also, optimal treatment poses greater difficulty as it remains controversial in most cases. We report a 47-year-old gentleman who presented with recurrent chylous pericardial effusion with no history of trauma, thoracic surgeries, cardiac disease and neoplasm in the past. Lymphoscintigraphy confirmed the communication between the lymphatic trunk and the pericardial space. The patient was managed conservatively with pericardial drainage and the patient recovered is doing well at present.

18F-FDG is the most commonly used radioisotope in PET scanning and is administered intravenously. When patients cannot cannulated, there are limited options available for functional tumour assessment. A fifty year old male presented for investigation of a suspected lung carcinoma identified during investigation of pneumonia. The patient had a severe needle phobia, intellectual disabilities and multiple co-morbidities which made cannulation impossible. An alternative administration method was sought, with successful oral administration occurring in both staging and restaging scans. The scans demonstrated resolution of a suspected lung cancer indicating it was an inflammatory/infective process, preventing the need for more invasive investigative approaches. A non-invasive and positive experience allowed for accurate diagnosis and repeat imaging for this patient, enabling follow up imaging to occur. It is reported that oral administration of 18F-FDG may be useful for assessment of suspected cancers for patients where cannulation isn’t possible, when limitations are taken into consideration.