INTRODUCTION: 68Ga-PSMA PET is an effective imaging modality in the evaluation of prostate cancer. However, there is limited data on its use in the evaluation of therapeutic response, particularly in radioligand therapy. OBJECTIVE: Our aim is to investigate the diagnostic accuracy of 68Ga-PSMA PET hybrid imaging in evaluating response to 177Lu-PSMA therapy in patients with mCRPC compared with the standard use of serum PSA. METHODOLOGY: A systematic review was done according to the Cochrane diagnostic accuracy reviews guidelines and the PRISMA checklist of literature from January 2015 to August 2020. Literature search, study selection, and data extraction were conducted by 2 reviewers. Statistical analysis of data was done using Meta-DiSc v1.4 RESULTS: A total of 5 studies were included following screening. A total of 128 patients were included in the review. Using PSA response as the reference standard, the pooled sensitivity and specificity of 68Ga-PSMA PET hybrid imaging to evaluate treatment response to 177Lu-PSMA therapy was 85% (Cl: 74 to 92%) and 74% (Cl: 62 to 84%), respectively. The computed diagnostic accuracy was 79.7%. CONCLUSION 68Ga-PSMA PET hybrid imaging is an effective diagnostic procedure in evaluating treatment response to 177Lu-PSMA therapy ligand therapy with good sensitivity, specificity, and diagnostic accuracy.
Gallium ; lutetium ; prostatic neoplasms

This is a case of a 66-year-old, Filipina, who presented with persistent proteinuria diagnosed with renal amyloidosis. In the presented case, the equivocal cardiac and incidental extracardiac findings in the Tc-99m pyrophosphate (Tc-99m PYP) scan aided in the diagnosis of primary systemic light chain amyloidosis (AL amyloidosis). Tc-99m PYP scan with single photon emission computed tomography (SPECT) is currently used as a non-invasive imaging modality to diagnose Transthyretin amyloidosis (ATTR amyloidosis) however its role in diagnosing AL amyloidosis is not well documented. The case highlights its role in detecting extracardiac amyloid burden and suggests possible biopsy sites. The researchers recommend an additional whole-body planar scan with possible SPECT/CT on the 3rd hour delay to survey other areas with possible amyloid protein deposit.
Philippines

18F-Fluorodeoxyglucose (18F-FDG) PET/CT scan is a vital imaging modality in the majority of oncologic situations. It is proven useful in staging, management and monitoring of lymphomas. Numerous subtypes of lymphomas exist; however, we present the first documented case of a 56-year-old, Filipino, male patient who is diagnosed with mantle cell lymphoma of the conjunctiva (MCL). MCL is an extremely rare type of extranodal non-Hodgkin lymphoma and has an aggressive nature with an estimated incidence of 2-4/1,000,000. This case highlights the critical role that PET/CT scans play in directing treatment decisions and monitoring the response of conjunctival MCL to therapy.
Lymphoma, Non-hodgkin ; Positron-emission Tomography

Introduction: Prostate cancer is the third most common cancer among Filipino males. Ga-68 PSMA PET-CT and Lu-177 PRLT have been introduced in the Philippines for the diagnostics and therapy of prostate cancer. Objective: The aim of this study is to compare treatment outcomes of standard therapy plus Lu-177 PSMA radioligand therapy and standard therapy alone among patients with prostatic cancer status-post castration using Ga-68 PET-CT as an outcome indicator. Methodology: This is an ambispective cohort study on Ga-68 PSMA PET-CT scans performed between January 1, 2018 and July 31, 2021. Serum PSA data taken within one month of the PET-CT scans were also collected when available. The PET-CT images were reviewed by a radiologist for RECIST response, and by a nuclear medicine physician for PERCIST response . Results: A total of 11 participants were included in the study. Six participants (55.5%) received standard therapy, while five participants (45.5%) received Lu-177 PSMA radioligand therapy plus standard therapy. There was no significant difference in the baseline and follow-up CT as shown by all p values > 0.05. A trend towards higher number of participants with non-complete/non-progressive RECIST response was noted in the control group than the treatment group, as well as higher number of participants with progressive or stable disease using the PERCIST response. Conclusion There were no significant differences noted in the clinical outcomes of participants who received Lu-177 PRLT and those with standard therapy alone. A trend towards decreasing serum PSA, CT and PET measurements were noted among patients given Lu-177 PRLT than those with standard therapy.
Prostatic Neoplasms

Introduction: A dipyridamole induced stress myocardial perfusion scintigraphy with Tc-99m Sestamibi is utilized for diagnosing coronary artery diseases. The use of dipyridamole as form of pharmacologic stressor has expected hemodynamic changes. Objective: The objective of this study was to determine the association of these changes with the scan parameters in patients with suspected coronary artery disease (CAD). Methodology: A total of 101 patients, with suspected CAD, who underwent a dipyridamole-induced stress myocardial perfusion scintigraphy using Tc-99m Sestamibi from January 2019 to March 2020 were included in this study. The patient databases, monitoring sheets, and scan results were reviewed . Results: The blood pressure responses had no significant association with the scan parameters and results. The normal (> 1.2) and abnormal (<1.2) heart rate ratios (HRR), which is the peak HR/baseline HR, likewise had no significant association with the scan results. However, in terms of the median HRR, the higher ratio of 1.29 (normal scan results) against the ratio of 1.25 (abnormal scan results) was determined to be significant (p-value of 0.032). The HRR also had a direct and indirect weak correlation with stress and rest Left Ventricular Ejection Fraction (LVEF) values (p-values of 0.09 and 0.011) and Summed Rest Score (p-value of 0.007), respectively. For the 12-L ECG, only the baseline normal (P-value of 0.018) and infarct findings (p-value of 0.017) were similarly associated with normal and abnormal scan results, respectively. Conclusion For patients with suspected CAD, the higher HRRs and baseline 12-L ECG of normal and infarct findings relates to the expected scan result. For scan parameters, the higher HRRs were also correlated with higher stress and rest LVEF values, and normal SRS, albeit a weak correlation. Notably, the blood pressure and post-infusion 12-L ECG changes had no significant association. In summary, the higher HRRs indicates normal scan results, normal SRS, and better LVEF values which increases the diagnostic confidence in the interpretation and management, especially in some equivocal cases.
Dipyridamole ; Myocardial perfusion scintigraphy

Background: The most recent pediatric diuretic imaging guidelines recommend the use of normalized residual activity (NORA) as a semiquantitative index of renal tracer drainage. It is defined as the ratio of post-void renal counts to 1-2 minute post-injection renal counts, with values less than 1 indicative of good drainage. We present two instances where NORA calculation was adjunctive in the evaluation of obstructive uropathy. Case Presentation: The first patient was a 3-month-old male with left-sided congenital hydronephrosis. On dynamic imaging, the diseased kidney showed adequate perfusion and parenchymal extraction; moderate to severe pelvicalyceal tracer retention exhibited good response to diuretic. The pre-diuretic NORA of 1.62 declined to 0.28 after furosemide challenge, concordant with imaging findings that were negative for obstruction. The second patient was a 7-week-old male, also with congenital hydronephrosis of the left kidney. Dynamic images showed the diseased kidney with diminished perfusion and function, as well as pelvicalyceal tracer retention which became more severe after the diuretic was given. The pre-diuretic NORA was 1.81, which became 1.18 post-diuretic. This inadequate decline supplemented imaging findings pointing to significant obstruction. Other semiquantitative parameters have preceded NORA; however, clearance half-time is not validated as a marker of obstructive uropathy in infants and children, and output efficiency requires specialized software to calculate. Standardization of NORA determination is largely provided for by the guidelines recommending a perirenal background region of interest, as well as minimizing the interval between starting camera acquisition and injecting the tracer. Conclusion Semiquantitative analysis through NORA calculation gives relevant supporting information in the reporting of renal tracer drainage among pediatric patients. Further studies are needed to ascertain its applicability among adults and its diagnostic value in a larger sample of affected Filipino children.

The introduction of peptide receptor radionuclide therapy (PRRT) to the Philippines has allowed for novel approaches in the management of neuroendocrine tumors (NETs). This case report details the management of a 66-year-old Filipino man diagnosed with metastatic pancreatic NET after biopsy and staging with Ga-68 DOTATATE PET-CT. After poor response to somatostatin analogue therapy, the patient was advised to undergo PRRT. Upon completing four cycles of PRRT with Lu-177 DOTATATE, the metastatic hepatic lesions showed resolution and the pancreatic tail tumor exhibited regression, allowing the patient to undergo surgical resection of the primary tumor. On follow-up, he was declared to be in remission with good quality of life and no imaging evidence of recurrence. The case underscores the diagnostic and therapeutic utility of radiolabeled somatostatin analogues along with the importance of a multidisciplinary approach in the management of an initially unresectable metastatic pancreatic NET
Receptors, Peptide ; Pancreatic Neoplasms ; Neuroendocrine Tumors

Background: Non-specific focal uptake in the skeleton is a diagnostic pitfall on 18F-PSMA-1007 PET/CT, but adjunctive measures to aid interpretation of these lesions are currently lacking. We present two cases where dual time point imaging provided additional information. Case Presentation: The first patient had a PI-RADS 3 lesion on MRI. No PSMA-avid abnormality was seen on PET, save for focal uptake in the right pubis with no anatomic correlate. Additional imaging showed a decrease in lesion SUV, and this was interpreted as benign. Another patient, diagnosed with prostate cancer, had multiple PSMA-avid pelvic foci. Two suspiciously malignant bone lesions had increasing SUV trend after dual time point imaging despite only faint sclerosis on CT. In contrast, one faint PSMA-avid lesion with no anatomic abnormality was read as benign after a decrease in SUV. A decrease in lesion SUV may point to a benign etiology, while an increase would heighten suspicion for malignancy. One possible molecular explanation is that a true PSMA-overexpressing lesion would bind to the tracer for a longer period than a false positive. Conclusion Dual time point imaging provides additional information that may be useful in the interpretation of non-specificskeletal lesions with increased 18F-PSMA-1007 uptake.
PSMA-1007 ; Positron Emission Tomography Computed Tomography

Diagnosis of Alzheimer dementia is done clinically using criteria set by different neurological associations. Inevitably, clinicians encounter cases that do not fulfill the set definitions and have to resort to supporting data to form a clinical judgment. Part of the ancillary work-up for dementia is the brain amyloid PET scan that has recently been available in the Philippines. It involves a radiopharmaceutical with high-affinity binding to amyloid plaques which for a time were thought to be central pathological finding for Alzheimer dementia. This study describes the first four amyloid PET scans in the Philippines and detail the protocol as well as interpretation of such studies. The procedure is not as simple and reproducible as one might think hence following the recommended protocol and interpretation guidelines are of utmost importance. We recommend standardization of the reporting of results for all centers that will cater to patients being worked up for dementia, which include reporting SUVRs for both whole cerebellum and cerebellar cortex. More studies are recommended to generate a local Florbetaben SUVR cutoff.
Alzheimer Disease ; Diagnostic Imaging

Introduction: No clear consensus exists as to the optimal timing for conducting whole body scintigraphy (WBS) after radioactive iodine (RAI) therapy for differentiated thyroid carcinoma. Objective: This study aimed to compare the utility of early versus delayed post-therapy WBS in identifying residual lesions and metastases. Methods A systematic review of existing literature was done, yielding 6 observational studies relevant to the subject. Meta-analyses were done comparing lesion detecting rates of early (3-4 days post-RAI) and delayed (7-11 days post-RAI) post-therapy WBS for thyroid remnants and metastases in the lymph nodes, lungs, and bone using a random-effects model with odds ratios (OR) and 95% confidence intervals (CIs). A subgroup analysis was also done relating to the type of collimator used in imaging.
Iodine-131 ; Thyroid Neoplasms ; Iodine Radioisotopes ; Radionuclide Imaging