Lutetium-177-PSMA-617 radioligand therapy in patients with high volume metastatic prostate cancer prior to chemotherapy and new generation androgen deprivation therapy: Clinical Experience

OBJECTIVE

We aimed to evaluate the efficacy oflutetium-177-prostate-specific membrane antigen-617 (177Lu-PSMA-617) with the luteinizing hormone releasing hormone (LHRH) analogues in the first or in the second-line setting formetastatic castration sensitive patients and metastatic castration resistance after progression with LHRH analogues.

SUBJECTS AND METHODS

Sixteen consecutive patients with high volume metastatic prostate cancer undergone 177Lu-PSMA-617 therapy who were refused chemotherapy and were unable to use new generation anti-androgen drugs because of unavailibility of reimbursement, were included in this retrospective study. Prostate specific antigen (PSA) response (>50% decrease), disease control rate (DCR: complete or partial response), progression-free survival (PFS) and overall survival (OS) were calculated to evaluate according to the clinicopathological features of the patients. Treatment response evaluated by 68Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT).

RESULTS

Mean age was 74,6 (SD±8,36). Among them, 7 (43,8%) patients has castration resistant disease, while the remaining has castration sensitive disease. Lutetium-177-PSMA-617 was administered to 10 (62,5%) patients as one of the first-line treatment and 6 patients received the treatment after progression on LHRH as a second-line treatment. Considering all patients, PSA response rate and DCR were 50% and 62% respectively. The median PFS and OS (with 95% CI) were 11,2 months (11-15) and 29 months (25,6-32,4), respectively in patients treated with 177Lu-PSMA-617 and LHRH analogues. Clinicopathological features and basal PSA level did not have effect on PSA response rates, DCR, OS and PFS. On the other hand, increment in PFS and OS (with 95% CI) was observed in castration resistant disease and in the second-line therapy; for castration resistant disease 16,5 months (12.3-19.7); 30 months (25.3-32.7), for the second-line therapy 14.5 months (12-20.5); 29 months (NR), respectively but statistically not significant. Serious toxicity was observed in a limited number of patients (18,7%), treatment-related death was not observed.

CONCLUSION

Favorable results can be achived with second-line 177Lu-PSMA-617 treatment in terms of OS and PFS, especially in castration-resistant disease, when chemotherapy and new generation ADT's cannot be used.

Comparison of 68Ga-FAPI-04 and 18F-FDG PET/CT for diagnosis of metastatic lesions in patients with recurrent papillary thyroid carcinoma

OBJECTIVE

We aimed to evaluate the gallium-68-labeled fibroblast-activation protein inhibitor (⁶⁸Ga-FAPI) positron emission tomography/computed tomography (PET/CT) in localizing papillary thyroid carcinoma (PTC) foci in patients with biochemical relapse. Papillary thyroid carcinoma has achieved biochemical recovery after appropriate treatment and had biochemical relapse in the last follow-up were included in this retrospective study. Gallium-68-FAPI and fluorine-18-fluorodeoxyglucose (⁶⁸F-FDG) PET/CT were performed to detect recurrence foci.

SUBJECTS AND METHODS

Biochemically relapsed patients who underwent total thyroidectomy and were diagnosed with pathologically differentiated thyroid cancer were included in our study. Gallium-68-FAPI and ¹⁸F-FDG PET/CT imaging methods were used to determine the focus of metastasis or recurrence in all patients.

RESULTS

Among 29 patients enrolled to the study, pathological subgroups were papillary (n=26) and poorly differentiated (n=3) PTC. Anti-thyroglobulin (TG) antibody positivity were noted in 5 of the patients, while all 29 of them were TG positive and had been consist of three groups as follows: 2-10ng/mL (n=4), 11-300ng/mL (n=14), 301ng/mL and above (n=11). Recurrence was detected in 72.4% (n=21) and 86% (n=25) of the patients via ¹⁸F-FDG and ⁶⁸Ga-FAPI, respectively. Accuracy of detection noted as 100% (5/5), 75% (3/4), and 92.9% (13/14) in groups with the anti-TG antibody positivity, TG levels of 2-10ng/mL and 11-300ng/mL, respectively, when the two imaging modalities were utilized together. Furthermore, accuracy of ⁶⁸Ga-FAPI was 100% (11/11) in the group with TG levels of 301ng/mL and above, whereas accuracy of ¹⁸F-FDG was 81.8% (9/11). Lastly, median maximum standardized uptake value (SUVmax) of recurrent lesions detected by the ⁶⁸Ga-FAPI (median SUVmax: 6.0) were statistically higher than the ones detected by the ¹⁸F-FDG (median SUVmax: 3.7) (P=0.002).

CONCLUSION

In recurrent PTC especially in case of higher TG levels, ⁶⁸Ga-FAPI can be used in patients with inconclusive ¹⁸F-FDG findings.

Comparison of [68Ga]-FAPI PET/CT and [18F]-FDG PET/CT in Multiple Myeloma: Clinical Experience

Objective: In this study, we aimed to compare [68Ga]FAPI PET/CT and [18F]FDG PET/CT imaging to detect lesions in multiple myeloma. Methods: A total of 14 patients with multiple myeloma who underwent [68Ga]FAPI PET/CT and [18F]FDG PET/CT imaging were included in this retrospective study. SUVmax values of [68Ga]FAPI and [18F]FDG were compared according to lesion locations. Also, lesion localization ability of both imaging methods was compared on the patient basis. Results: In 4 of 14 patients, [68Ga]FAPI PET/CT and [18F]FDG PET/CT have not detected any bone lesions. In 8 of the remaining 10 patients [18F]FDG PET/CT detected bone lesions but in this group, 6 patients showed more higher SUVmax values than [18F]FDG PET/CT in [68Ga]FAPI PET/CT.In contrast, 2 of 8 patients showed more higher SUVmax values than [68Ga]FAPI PET/CT in [18F]FDG PET/CT. Moreover, [68Ga]FAPI PET/CT detected bone lesions in two patients, which werenot detected by [18F]FDG PET/CT. Also, in five patients, [68Ga]FAPI PET/CT showed more bone lesions in comparison with[18F]FDG PET/CT. Only one patient, [18F]FDG PET/CT showed more bone lesions. Three extramedullary involvements were observed in the following locations: lung, presacral lymph node, and soft tissue mass lateral to the right maxillary sinus. Among these involvements, higher SUVmax values were observed in the lung and presacral lymph node with [68Ga]FAPI compared to [18F]FDG. However, the soft tissue mass showed a higher SUVmax value in [18F]FDG than [68Ga]FAPI. Conclusions: No significant superiority was observed in [68Ga]FAPI PET/CT over [18F]FDG PET/CT in patients with MM. However, [68Ga]FAPI PET/CT can be utilized as a complementary imaging method to [18F]FDG PET/CT in some settings, especially in low-[18F]FDG affinity and inconclusive cases. Considering the favorable aspects of [68Ga]FAPI PET/CT in MM, such as low background activity, absence of non-specific bone marrow, and physiological brain involvement, further studies with a larger sample size should be conducted.

Clinical significance of incidental FDG uptake in the prostate gland detected by PET/CT

The value of FDG-positron emission tomography/computed tomography (PET/CT) for detecting prostate cancer is unknown. We aimed to investigate the clinical value of incidental prostate FDG uptake on PET/CT scans. We reviewed 6128 male patients who underwent FDG-PET/CT scans and selected cases that reported hypermetabolic lesion in the prostate. The patients who have prior history of prostate carcinoma or prostate surgery were excluded from the study. We have analyzed the correlation between PET/CT findings and serum prostate-specific antigen (PSA) levels, imaging (USG), urological examinations and biopsy. Incidental 18F-FDG uptake of the prostate gland was observed in 79 patients (1.3%). While sixteen of them were excluded due to inadequate clinical data, the remaining 63 patients were included for further analysis. The patients were divided into two groups; 8 patients (12.7%) in the malignant group and 55 patients (87.3%) in the benign group. The SUVmax values were not significantly different between the two groups. In 6 (75%) patients with prostate cancer, FDG uptake was observed focally in the peripheral zone of the prostate glands. There was no significant correlation between the SUVmax and the PSA levels. Incidental 18F-FDG uptake in the prostate gland is a rare condition, but a substantial portion of it is associated with the cancer. Benign and malignant lesions of the prostate gland in FDG-PET/CT imaging could not be reliably distinguished. The peripheral focally FDG uptake of prostate glands should be further examined with the clinical and labaratory evaluations.

A different concept in the application of dacryoscintigraphy

PURPOSE

Current dacryoscintigraphy methods have several potential pitfalls, the most important of which is the outflow of tears. Another is the difficulty in fixing the head with the patient seated. To overcome these difficulties, a new method was applied.

MATERIALS AND METHODS

The study included 77 persons: 43 controls and 34 patients with epiphora. Two methods were applied to the two groups. In the first, protocol 1 (the current conventional protocol), the patient was seated in front of a gamma camera and one drop (50 microl) Tc-99m pertechnetate containing 50 to 100 microCi radioactivity was instilled in the inferior fornix or outer canthus of the eye and dynamic and static images were obtained for approximately 15 to 20 minutes. In the other, protocol 2 (our protocol), 100 microCi (10 microl) Tc-99m pertechnetate was instilled in the outer canthus of the eye using a micropipette with the patient in the supine position under the gamma camera. Dynamic images were taken for only 5 minutes.

CONCLUSION

The pitfalls and difficulties seen with protocol 1 were lessened to a great degree in protocol 2.

Investigation of perfusion reserve using 99Tc(m)-MIBI in the lower limbs of diabetic patients

This study aimed to investigate the microvascular pathology in the lower limbs of diabetic patients without symptoms or findings of peripheral ischaemia by measuring perfusion reserve scintigraphically. It was carried out in 47 female subjects who had no evidence of peripheral arterial disease in their history, physical examination or Doppler ultrasonography. The diabetic group consisted of 25 women (mean age 54.2 +/- 3.54 years) with type II diabetes mellitus of more than 10 years' duration. A control group consisted of 22 healthy non-diabetic women (mean age 50.14 +/- 6.75 years). Each subject flexed their right foot maximally both dorsally and plantar 60 times. In the middle of this exercise, 370 MBq technetium-99m-methoxyisobutylisonitrile (99Tc(m)-MIBI) was injected intravenously. Ten minutes after the injection, a posterior image of both calves was obtained using a gamma camera. Rectangular regions of interest were symmetrically drawn over both calves. The total count in the resting calf was subtracted from the total count in the exercising calf, and the percentage increase, termed the perfusion reserve, was determined. A significant difference was found between the perfusion reserves of the diabetic and control groups (76.04 +/- 12.96% and 95.91 +/- 12.83%, respectively; P<0.001). In conclusion, microvascular pathology may be determined scintigraphically by measuring the perfusion reserve in the lower limb muscles in diabetic patients. This method may also be used to evaluate perfusion abnormalities in other circulatory disorders.