Asia Oceania Journal of Nuclear Medicine & Biology
Volume:9 Issue: 1, Winter and Spring 2021

A limitation to the wider introduction of personalised dosimetry in theranostics is the relative paucity of imaging radionuclides with suitable physical and chemical properties to be paired with a long-lived therapeutic partner. As most of the betaemitting therapeutic radionuclides emit gamma radiation as well they could potentially be used as the imaging radionuclide as well is the therapeutic radionuclide. However, the downsides are that the beta radiation will deliver a significant radiation dose as part of the treatment planning procedure, and the gamma radiation branching ratio is often quite low. Gallium-67 has been in use in nuclear medicine for over 50 years. However, the tremendous interest in gallium imaging in theranostics in recent times has focused on the PET radionuclide gallium-68. In this article it is suggested that the longer-lived gallium-67, which has desirable characteristics for imaging with the gamma camera and a suitably long half-life to match biological timescales for drug uptake and turnover, has been overlooked, in particular, for treatment planning with radionuclide therapy. Gallium-67 could also allow non-PET facilities to participate in theranostic imaging prior to treatment or for monitoring response after therapy. Gallium-67 could play a niche role in the future development of personalised medicine with theranostics.

In patients with papillary thyroid cancer (PTC), sentinel lymph node (SLN) radio-guided biopsy is not routinely used for detection of involved neck lymph nodes (NLN); 99mTc-sulfur colloid antimony (99mTc-SC) has been used for this purpose. In this study, besides 99mTc-SC another radiotracer, 99mTc-phytate (99mTc-P) with different doses and injection methods were evaluated. Twenty-two patients, scheduled to undergo thyroidectomy for PTC, were injected for radio-guided SLN biopsy in the morning of operation in 3 groups: intra tumoral injection of about 1 mCi 99mTc-P (group A; n=5); peritumoral injection of less than 3 mCi 99mTc-SC (group B; n=6); and peritumoral injection of 3 to 5 mCi 99mTc-SC with application of massage (group C; n=9). A patient refused to complete the study. No NLN was detected in the pre-operative ultra-sonographic examinations of all patients. Central neck dissection was done for all the participants. The presence of radio guided detected NLN and results of pathology were assessed. In group A and B, no SLN was detected. NLNs were resected in 4 patients in group A and B; 2 of them involved by the tumor. In group C, 6 out of 9 patients (66.7%) had between 1 to 6 SLNs; the procedure failed to detect SLN in a patient in group C with surgically resected reactive NLN (failure rate 1 out of 7). The results underscored the significance of SLN radio guided biopsy in patients with PTC; the radiotracer, dose and method of injection may affect the detection rate.

Objective(s) :

18F-Fluorodeoxyglucose (FDG) uptake in children is different from that in adults. Physiological accumulation is known to occur in growth plates, but the pattern of distribution has not been fully investigated. Our aim was to evaluate the metabolic activity of growth plates according to age and location.

We retrospectively evaluated 89 PET/CT scans in 63 pediatric patients (male : female = 25 : 38, range, 0–18 years). Patients were classified into four age groups (Group A: 0–2 years, Group B: 3–9 years, Group C: 10–14 years and Group D: 15-18 years). The maximum standardized uptake value (SUVmax) of the proximal and distal growth plates of the humerus, the forearm bones and the femur were measured. The SUVmax of each site and each age group were compared and statistically analyzed. We also examined the correlations between age and SUVmax.

As for the comparison of SUVmax in each location, the SUVmax was significantly higher in the distal femur than those in the other sites (p < 0.01). SUVmax in the distal humerus and the proximal forearm bones were significantly lower than those in the other sites (p < 0.01). In the distal femur, there was large variation in SUVmax, while in the distal humerus and the proximal forearm bones, there was small variation. As for the comparison of SUVmax in each age group, the SUVmax in group D tended to be lower than those in the other groups, but in the distal femur, there was no significant difference among each age group.

Our data indicate that FDG uptake in growth plates varies depending on the site and age with remarkable uptake especially in the distal femur.

The aim of the study was to create a local normal database brain template of Thai individuals for 11C-Pittsburgh compound B (11C-PiB) and 18F-THK 5351 depositions using statistical parametric mapping (SPM) software, and to validate and optimize the established specific brain template for use in clinical practice with a highly reliability and reproducibility. This prospective study was conducted in 24 healthy right-handed volunteers (13 men, 11 women; aged: 42–79 years) who underwent 18F-THK 5351 and 11C-PiB PET/CT scans. SPM was used for the 18F-THK 5351 and 11C-PiB PET/CT image analysis. All PET images were processed individually using Diffusion Tensor Image -Magnetic Resonance Imaging-weighted images (DTI-MRI images), which involved: (1) conversion of Digital Imaging and Communications in Medicine (DICOM) files into an analyzable file extension (.NIFTI) for statistical parametric mapping, (2) setting of the origin (the anterior commissure was used as the anatomical landmark), (3) re-alignment, (4) co-registration of PET with B0 (T1W) and DTI-MRI images, (5) normalization, and (6) normal verification using the Thai MRI standard. We then compared the normal PET template with the abnormal deposition area of different dementia syndromes, including Alzheimer’s disease and progressive supranuclear palsy. This method was able to differentiate cognitively normal from Alzheimer’s disease and progressive supranuclear palsy subjects. This normal brain template was able to be integrated into clinical practice and research using PET analyses at our center.

Myocardial perfusion imaging is a non-invasive procedure that plays an integral role in the diagnosis and management of coronary artery disease. With the routine use of computerised tomography attenuation correction (CTAC) in myocardial perfusion imaging still under debate, the aim of this review was to determine the impact of CTAC on image quality in myocardial perfusion imaging. Medline, Embase and CINAHL were searched from the earliest available time until August 2019. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies version 2. Details pertaining to image quality and diagnostic accuracy were analysed and results summarised descriptively. Three studies with ‘unclear’ risk of bias and low applicability concerns (1002 participants) from a yield of 2725 articles were identified. Two studies demonstrated an increase in image quality, and one study found no difference in image quality when using CTAC compared to no attenuation correction. Benefits of CTAC for improving image quality remain unclear. Given the potential exposure risk with the addition of CTAC, patient and clinician factors should inform decision making for using of CTAC in myocardial perfusion imaging for coronary artery disease.

Non-Hodgkin lymphoma (NHL) is a group of malignant lymphoproliferative disorders arising predominantly in the lymph nodes with various clinical and histological characteristics. At least 25% of NHL originates from tissues other than lymph nodes and sometimes even from sites that do not contain lymphoid tissue. These are referred to as primary extranodal lymphomas (pENLs). pENL is a universal diagnostic challenge to the clinicians and pathologists due to their varied clinical presentations, morphological mimicry, and molecular alterations. The GIT is the most common site of pENL followed by nasopharynx/oropharynx, testis, uterus/ovary, thyroid, and central nervous system. Long bones (tibia), maxillary sinus, skin, and paraspinal soft tissues are the other rare anatomic sites of pENL. We reported a case of a 60-year-old female presented with pain and mass in the pelvis region. 18F-Fluorodeoxyglucose(FDG) PET/CT was done, which revealed extensive extranodal involvement of the lung, bilateral kidneys, uterus, ovaries, bones, and muscles with no involvement of lymph nodes or lymphomatous organs. Extensive extranodal involvement with sparing of lymphomatous organ has not been reported earlier.

High-grade B-cell lymphoma, an aggressive form of Non-Hodgkin’s Lymphoma, is known as a double or triple hit lymphoma based on the presence of MYC and BCL2 without or with BCL6 genetic rearrangements, respectively. It carries a poorer prognosis, compared to other variants of B-cell lymphoma, and its management also differs which requires more intensive chemotherapy in contrast to the routine regimen. Terminal deoxynucleotidyl transferase (TdT), a marker of immaturity is commonly expressed in B-cell lymphoblastic leukemia or lymphoma (B cell ALL) which is absent in mature forms of B-cell lymphoma. The TdT is expressed in highgrade B-cell lymphoma; therefore, it poses a classification and management dilemma, which should be accurately differentiated from B-cell ALL and mandates molecular analysis. Herein, we report a case of a 52-year-old female with biopsy reported as high-grade B-cell lymphoma with TdT expression. She was referred for Fluor-deoxyglucose (FDG) Positron Emission Tomography-Computed Tomography (PET/CT) scan for staging in the absence of molecular analysis for Bcell ALL. It was diagnosed as lymphoma on FDG PET/CT based on its characteristic findings of extensive extranodal involvement of multiple organs with no significant lymphadenopathy establishing the incremental value of FDG PET/CT scan, which helped the clinician to arrive at a conclusion.

Celiac disease is an immune-mediated disorder triggered by hypersensitivity to gluten occurring in genetically susceptible individuals. A high-index of suspicion is needed for diagnosis as patients can be asymptomatic or present with atypical symptoms or extra-intestinal manifestations. Typical 18-F Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET)/Computed Tomography (CT) gastrointestinal manifestations of celiac disease include increased multifocal or diffuse jejunal and ileal uptake; focal duodenal uptake is less common. Splenomegaly with increased splenic FDG uptake is also uncommon in celiac disease in the absence of portal hypertension; small-sized spleen and functional hyposplenism are more typical. We report a case of celiac disease diagnosed after PET/CT showed FDG uptake in the duodenum and enlarged spleen. Follow-up after gluten-free diet showed complete metabolic resolution and regression of splenomegaly. The combination of focal bowel and splenic uptake is unusual in celiac disease and may be mistaken for a lymphoproliferative disorder. Awareness of this entity may avoid misdiagnosis and guide appropriate management.

The role of 18F-FDG PET/CT in patients with multiple myeloma (MM) and other plasma cell disorder is well known. Solitary plasmacytoma (SP), an extremely rare form within this entity that accounts for approximately 4% of plasma cell malignancies, can be classified as solitary bone plasmacytoma (SBP) or solitary extramedullary plasmacytoma (SEMP). EMP (extramedullary plasmacytoma) is a rare neoplasm characterized by the monoclonal proliferation of plasma cells outside the bone marrow. Breast and craniocerebral region are the uncommon sites of presentations of EMP and rarely reported in the literature. The most frequent site of presentation is upper airways. EMPs have similar pathogenesis as MM, however, they differ in management as they are radiosensitive in nature, and radiotherapy is the preferred treatment modality. As solitary EMP has a better prognosis than SPB with a lower conversion rate to MM, accurate staging is essential to plan the treatment. 18F-FDG PET/CT has higher sensitivity for treatment response evaluation. In the present case series, it is aimed to depict the role of 18F-FDG PET/CT in newly diagnosed solitary EMP with different sites of origin to exclude further lesions which lead to change in a treatment plan and in treatment response assessment.

Rosai Dorfman disease is a rare form of nonlangerhans cell histiocytosis, presenting with extensive lymphadenopathies. Treatment in most cases of nodal disease, involves close observation; however, extranodal involvement requires a more definitive treatment strategy. Herein, we report a case of extensive Rosai Dorfman disease in a 43-year-old woman presenting for evaluation of treatment response by 18F-FDG PET/CT after frequent relapses and disease progression. In addition to extensive lymphadenothapies in cervical, supraclavicular, superior mediastinum, axillary, abdominopelvic and inguinofemoral regions, the patient had metabolically active bone and subcutaneous lesions which were not previously recognized. Following this 18F-FDG PET/CT study, the patient management was changed to sirolimus and prednisolone. To choose the best treatment option for Rosai Dorfman patients, knowledge of the full extent of disease is important. Compared with conventional imaging, 18F-FDG PET/CT has the advantage of being a whole-body imaging modality and can recognize disease involvement prior to any anatomical changes.

We present a case of metastatic prostate cancer with rare metastases involving the brain and orbit, in addition to liver, skeletal and nodal metastases. The patient had undergone prior hormonal therapy and chemotherapy and had disease progression despite 2 cycles of 177Lu-Prostate specific membrane antigen (177Lu-PSMA) based radioligand therapy. He had a partial response after 2 cycles of 225Ac-PSMA based targeted alpha therapy, as demonstrated on the 68Ga-PSMA PET/CT study. However, the patient had disease progression at the end of 4 cycles of 225Ac-PSMA therapy, evident by rising prostate specific antigen levels and imaging findings. The end of treatment 68Ga-PSMA PET/CT showed additional sites of metastases in the orbit and brain apart from overall disease progression. These are rare sites of distant spread in prostate cancer and require urgent evaluation and local treatment to prevent potential complications. The importance of detection of metastatic sites in closed cavities is because of the requirement for urgent intervention to avoid compression related complications.

A 73-year-old man with lung cancer underwent bone scintigraphy for disease staging. Diffuse myocardial 99m technetium hydroxymethylene diphosphonate (99mTc-HMDP) uptake was incidentally found. A diagnosis of amyloid transthyretin (ATTR) cardiac amyloidosis was suspected, although the patient had no symptoms at this time. Single-photon emission computed tomography (SPECT) showed particularly strong uptake in the ventricular septum. Cardiac magnetic resonance imaging (CMR) showed widespread subendocardial and partly transmural enhancement of the left ventricular myocardium on delayed postcontrast T1-weighted images. These findings were consistent with ATTR cardiac amyloidosis. 18F-FDG uptake in the left ventricle wall was observed on PET/CT. He was finally diagnosed with ATTR by endomyocardial biopsy. There are two major subtypes of cardiac amyloidosis: ATTR amyloidosis and amyloid light-chain (AL) amyloidosis. Endomyocardial biopsy is the gold standard for diagnosis. Recently, however, several reports have shown that bone scintigraphy using a 99mTc-labelled bone-seeking agent can detect ATTR cardiac amyloidosis and differentiate it from AL amyloidosis. Bone scintigraphy may play an important role in the detection and differentiation of ATTR cardiac amyloidosis.

Chordoma is a rare bone cancer which arises from undifferentiated notochordal remnants in the axial skeleton. It generally has slow-growing and locally aggressive behavior. This tumor is usually diagnosed by CT and MRI modalities and the role of SPECT/CT is still debated. It shows reduced or normal uptake of radioisotope on bone scanning and increased tracer uptake is infrequently reported. Here we present a 33-year-old man with complaint of low back pain and numbness of his right leg. The whole body bone scan showed relatively uniform radiotracer activity throughout the skeleton. A focal increased uptake in the second lumbar vertebra was noted on SPECT/CT images. SPECT/CT also demonstrated multiple lytic lesions in lumbar vertebrae. The lesions were proven to be chordoma on biopsy. Lumbar chordoma could be one of the differential diagnoses for lytic lesions of the vertebrae which show absent or minimal tracer uptake on bone scintigraphy and SPECT/CT imaging. Our case was unusual as the patient was very young for chordoma diagnosis and bone scan showed increased uptake adjacent to the involved vertebral lesion detected by SPECT/CT.