68Ga-PSMA Versus 18F-FDG PET/CT in the Evaluation of Epithelioid Hemangioendothelioma.

ABSTRACT: A 32-year-old man with epithelioid hemangioendothelioma was imaged with 68Ga-PSMA PET/CT to evaluate the potential of 177Lu-PSMA radionuclide therapy after progression findings were observed on follow-up 18F-FDG PET/CT imaging. Liver lesions showed low FDG SUVmax. The lesion-to-background ratio (TBR) was calculated as 5.1/2.9 on 18F-FDG PET/CT imaging. However, 68Ga-PSMA PET/CT showed moderate PSMA SUVmax. TBR was calculated as 4.5/1.1. In conclusion, in this case report, we demonstrated that 68Ga-PSMA with moderate TBR in epithelioid hemangioendothelioma may be promising for 177Lu-PSMA radionuclide therapy.

Should new organ involvement be included in Response Evaluation Criteria in PSMA Imaging?

PURPOSE: The current study is intended to investigate the effect of new organ involvement on overall survival (OS) and modify the Response Evaluation Criteria in PSMA Imaging (RECIP) by including new organ involvement to RECIP 1.0. MATERIALS AND METHODS: This retrospective study includes 114 patients diagnosed with metastatic castration-resistant prostate cancer (mCRPC) between September 2017 and June 2022 who had received docetaxel treatment and had baseline and post-treatment prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) images. The inclusion criteria were patients with pre- and post-treatment [18F]FDG PET/CT images and whose [18F]FDG PET images were negative. Those whose data were unavailable, who had additional malignancy, or who received abiraterone, enzalutamide, or Lutetium (Lu)-177 treatment were excluded. Age, Gleason score (GS), TPSA (total prostate-specific antigen) levels, surgical history, and OS information were recorded for each patient. RESULTS: The 114 patients herein had a median age of 72.5 (51-91) years and a median GS of 8 (7-10). New lesions were observed in 59 patients (51.7%) and new organ PSMA uptake was observed in 14 patients (12.2%). In the multivariate Cox regression analysis, volume-based treatment response (vTR)-total lesion PSMA (TLP), RECIP PSMA-VOL, modified RECIP (mRECIP) PSMA-VOL, and mRECIP TLP were independent prognostic factors for mortality (p < 0.001, p = 0.006, p = 0.003, and p = 0.003, respectively). The median OS of patients with new organ involvement and new lesion with PSMA uptake was 9.3 months (95% CI 2.1-16.5 months) and 11.8 months (95% CI 7.4-16.2 months), respectively. CONCLUSION: The study concluded that new organ involvement had a shorter OS than new lesion involvement. In the mRECIP that we developed, unlike RECIP, we demonstrated that both PSMA-VOL and TLP value were independent prognostic factors for mortality.

Local imaging to interpret tumor size in F18 fluorodeoxyglucose positron emission tomography/CT in lung cancers.

OBJECTIVE: This study aimed to determine the thoracic and extra-thoracic extension of the disease in patients diagnosed with lung cancer and who had whole-body F18-fluorodeoxyglucose positron emission tomography/CT imaging and to investigate whether there is a relationship between tumor size and extrathoracic spread. METHODS: A total of 308 patients diagnosed with lung cancer were included in this study. These 308 patients were first classified as group 1 (SPN 30 mm>longest lesion diameter ≥10 mm) and group 2 (lung mass (longest lesion diameter ≥30 mm), and then the same patients were classified as group 3 (nodular diameter of ≤20 mm) and group 4 (nodular size of >20 mm). Group 1 was compared with group 2 in terms of extrathoracic metastases. Similarly, group 3 was compared with group 4 in terms of frequency of extrathoracic metastases. F18 fluorodeoxyglucose positron emission tomography/CT examination was used to detect liver, adrenal, bone, and supraclavicular lymph node metastasis, besides extrathoracic metastasis. RESULTS: Liver, bone, and extrathoracic metastasis in group 1 was statistically lower than in group 2 (p<0.001, p<0.01, and p=0.03, respectively). Liver, extrathoracic, adrenal, and bone metastasis in group 3 was statistically lower than that in group 4 (p<0.001, p=0.01, and p=0.04, p<0.01, respectively). The extrathoracic extension was observed in only one patient in group 3. In addition, liver, adrenal, and bone metastases were not observed in group 3 patients. CONCLUSION: Positron emission tomography/CT may be more appropriate for cases with a nodule diameter of ≤20 mm. Performing local imaging in patients with a nodule diameter of ≤20 mm could reduce radiation exposure and save radiopharmaceuticals used in positron emission tomography/CT imaging.

The Role of 68Ga FAPI-04 and 18F-FDG PET/CT in Detecting Liver Metastases in Different Types of Cancer.

OBJECTIVE: We compared the diagnostic accuracies of 68Ga FAPI-04 PET/CT and 18F-FDG PET/CT for detecting liver metastases (LMs) in patients with different cancer types. MATERIALS AND METHODS: This retrospective study included 63 patients with liver lesions who underwent 18F-FDG PET/CT and 68Ga-FAPI-04 PET/CT between May 2020 and May 2022. Patients with histopathologically confirmed primary diagnoses, data that could be accessed retrospectively, liver lesions confirmed by biopsy over at least 3-6 months of follow-up (via ultrasonography, CT, magnetic resonance imaging, PET/CT, or laboratory tests) were included. Patients with secondary malignancies or primary liver malignancies, and/or who could not be followed-up, were excluded. RESULTS: Of the 63 total patients, 34 (54%) were female, and the mean age was 61 (30-92) years. There were 582 LMs in 51 patients and 35 benign liver lesions in 20 (12 patients had only benign and 8 both benign and malignant lesions). Of the 582 LMs, 472 (81.1%) evidenced 18F-FDG uptake and 572 (98.2%) 68Ga-FAPI uptake. The diagnostic accuracies of 68Ga-FAPI PET/CT and 18F-FDG PET/CT were 98% and 82%, respectively (p < 0.001; McNemar test). When the LMs were compared, the maximum standardized uptake (SUVmax) value was significantly higher on 18F-FDG PET/CT than 68Ga-FAPI PET/CT (median: 6.0 vs. 5.4; p = 0.016). However, the LM-to-background ratio (TBR) was significantly higher on 68Ga-FAPI PET/CT than 18F-FDG PET/CT (median: 4.1 vs. 2.1; p < 0.001). CONCLUSION: 68Ga-FAPI PET/CT detected more LMs than did 18F-FDG PET/CT, and TBR was significantly higher on 68Ga-FAPI PET/CT than 18F-FDG PET/CT.

Role of volumetric parameters obtained from 68 Ga-PSMA PET/CT and 18F-FDG PET/CT in predicting overall survival in patients with mCRPC receiving taxane therapy.

OBJECTIVE: The aim of this study was to determine the prognostic role of volumetric parameters and Pro-PET scores obtained from 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT and 18F-FDG PET/CT in patients with metastatic castration-resistant prostate cancer (mCRPC) receiving taxane therapy. MATERIALS AND METHODS: The study included 71 patients who underwent simultaneous PSMA and 18F-FDG PET/CT imaging between January 2019 and January 2022, had a Pro-PET score of 3-5 and had received taxane therapy after imaging. 18F-FDG tumor volume (TV-F) and PSMA tumor volume (TV-P) values of the lesions and total lesion glycolysis (TL-G) and total lesion PSMA (TL-P) values of the lesions were calculated on both imaging studies and the effects of these parameters on overall survival (OS) were investigated. RESULTS: The median age of the patients included herein was 71 years (56-89) and the median prostate-specific antigen (PSA) level was 16.4 (0.01-1852 ng/dL). According to the Kaplan-Meier survival analysis, TTV-P ≥ 78.5, TTL-P ≥ 278.8, TTV-F ≥ 94.98, TTL-G ≥ 458.3, TTV-P + F ≥ 195.45, TTL-G + P ≥ 855.78, lymph node (L)TV-FDG ≥ 3.4, LFDG-SUVmax ≥ 3.2, LFDG-SUVmean ≥ 2.25, LFDG-SUVpeak ≥ 2.55, and bone (B)TV-F ≥ 51.15 values were found to be prognostic factors in predicting short OS. Multivariate Cox regression analysis showed that a Vscore ≥ 3 (95% confidence interval [CI]: 7.069-98.251, p < 0.001) and TTL-G + P ≥ 855.78 (95% CI: 4.878-1037.860, p = 0.006) were found to be independent prognostic factors in predicting short OS. CONCLUSION: Volumetric parameters and Pro-PET scores obtained from 68 Ga-PSMA PET/CT and 18F-FDG PET/CT imaging have been shown to have an impact on OS in patients with mCRPC receiving taxane therapy.

Comparison of the role of 18 F-fluorodeoxyglucose PET/computed tomography and 68 Ga-labeled FAP inhibitor-04 PET/CT in patients with malignant mesothelioma.

OBJECTIVE: In this study, we aimed to compare the role of 68 Ga-labeled FAP inhibitor ( 68 Ga-FAPI)-04 PET/computed tomography (CT) and 18 F-fluorodeoxyglucose ( 18 F-FDG) PET/CT in the evaluation of primary tumor and metastases in patients diagnosed with malignant mesothelioma. MATERIALS AND METHODS: Our prospective study included 21 patients with histopathological diagnosis of malignant mesothelioma who underwent both 68 Ga-FAPI-04 PET/CT and 18 F-FDG PET/CT imaging between April 2022 and September 2022. Maximum standardized uptake value (SUVmax), metabolic tumor volume, total lesion glycolysis, tumor-to-background ratio (TBR) and highest SUVpeak (HPeak) values and lesion numbers were calculated from primary and metastatic lesions on FDG and FAPI PET/CT images. Findings obtained from FAPI and FDG PET/CT were compared. RESULTS: More lesions were detected in 68 Ga-FAPI-04 PET/CT compared to 18 F-FDG PET/CT in primary tumor and lymph node metastases. Statistically significantly higher SUVmax and TBR values were found with FAPI PET/CT (primary lesion SUVmax and TBR, P  = 0.001 and P  < 0.001, respectively; lymph node SUVmax and TBR, P  = 0.016 and P  = 0.005, respectively). With FAPI PET/CT, upstage was observed according to tumor-node-metastasis staging in a total of seven patients including three patients with pleural origin, three patients with peritoneal origin and one patient with pericardial origin. CONCLUSION: In addition to the stage change with 68 Ga-FAPI-04 PET/CT in malignant mesothelioma patients, a statistically significant superiority was observed in SUVmax, TBR and volumetric parameters in primary tumors and metastases.

The prognostic role of whole-body volumetric 68 GA-DOTATATE PET/computed tomography parameters in patients with gastroenteropancreatic neuroendocrine tumor treated with 177 LU-DOTATATE.

OBJECTIVE: The aim of this study is to evaluate the prognostic role of Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and quantitative 68 Ga-DOTATATE PET/computed tomography parameters such as maximum standardized uptake value (SUVmax), mean SUV (SUVmean), DOTATATE tumor volume (DTV), total lesion DOTATATE (TLD) in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) treated with 177 Lu-DOTATATE. MATERIAL AND METHOD: Our retrospective study included 21 patients with GEP-NETs treated with 177 Lu-DOTATATE between January 2017 and January 2022. SUVmax, SUVmean, SUVmax/spleenSUVmax (SUVmax/Sx), DTV, TLD, SUVmean/spleenSUVmean (SUVmean/Sm), TLD/Sm values were calculated and recorded for all patients before and after 177 Lu-DOTATATE treatment. RESULTS: A total of 319 metastases were detected in the patients included in the study, and a total of 68 target lesions were selected. In univariant Cox regression analysis, TLD/Sm percent change (∆TLD/Sm) was found to be statistically significant on overall survival (OS) ( P  = 0.044). The 3-year survival in nonresponders was 50% ( P  = 0.034) based on ∆SUVmax/Sx values, 50% ( P  = 0.002) based on RECIST values, 50% based on ∆TDTV + new lesion values ( P  = 0.033), and according to ∆TTLD + new lesion values, it was 66% ( P  = 0.030). CONCLUSION: In our study, we showed that SUVmax/Sx, RECIST, ∆TDTV + new lesion, and ∆TTLD + new lesion parameters can predict OS in the evaluation of response to treatment.

Comparison of 68GA-FAPI-04 PET/CT and 18F-FDG PET/CT findings in peritonitis carcinomatosa cases.

OBJECTIVE: This study was conducted to compare the diagnostic accuracy of gallium-68-radiolabeled fibroblast activation protein inhibitor (68Ga-FAPI-04), positron emission tomography/computed tomography (PET/CT), and fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT based on the peritoneal carcinomatosis (PC) index for detecting peritoneal metastases of various cancer types, and to evaluate the potential benefits of FAPI PET/CT in patients with peritoneal metastases. SUBJECTS AND METHODS: This retrospective study included 57 patients with peritoneal metastases between November 2020 and December 2021. All patients underwent 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT scans within 7 days. RESULTS: Among the 57 patients included, 32 (56.1%) were male and the median age was 54 years (22-86 years). In the visual evaluation made from a total of 13 quadrants on the abdominopelvic peritoneal surfaces, positive findings were observed in 111 quadrants in 39 patients by 18F-FDG PET/CT and in 280 quadrants in 57 patients by 68Ga-FAPI-04 PET/CT (P<0.001). The maximum standardized uptake value (SUVmax) and target-to-background ratio (TBR) values of 68Ga-FAPI-04 PET/CT for the PC lesions were significantly higher than the SUVmax and TBR values of 18F-FDG PET/CT in all patients and in all quadrants (SUVmax 6.45 vs 4.1; P<0.001; TBR 14.9 vs 6.8; P<0.001). CONCLUSION: Gallium-68-FAPI-04 PET/CT showed superior sensitivity compared to 18F-FDG PET/CT in both quantitative and visual evaluations of PC. Considering the low background activity and higher specific activity uptake values, 68Ga-FAPI-04 PET/CT helped improve diagnostic accuracy.

Superiority of 18 F-FDG PET/CT to 68 GA-FAPI PET/CT in Adrenocortical Tumor Imaging.

ABSTRACT: 18 F-FDG PET/CT was performed to evaluate the response to treatment in a 62-year-old female patient who was operated for adrenocortical carcinoma. High FDG uptake was observed in recurrent lesion in the left adrenal gland site and metastatic lesions. In the 68 Ga-FAPI-04 PET/CT study, low FAPI uptake was observed in both recurrences and metastases. In this case, we demonstrated the superiority of 18 F-FDG PET/CT over 68 Ga-FAPI-04 PET/CT in the evaluation of adrenocortical carcinoma.

68 GA-FAPI-04 PET/CT Versus 18 F-FDG PET/CT in Imaging of Malignant Mixed Germ Cell Testicular Tumor.

ABSTRACT: 18 F-FDG PET/CT imaging was performed for restaging in in a 16-year-old boy who was operated on for right testicular tumor and was diagnosed with malignant mixed germ cell tumor. Mild FDG uptake was observed in 2 nodules in both lungs and retroperitoneal lymph node in the abdomen. 68 Ga-FAPI (fibroblast activation protein inhibitor) 04 PET/CT showed moderate uptake of FAPI in lung nodules and retroperitoneal lymph node. In this case, 68 Ga-FAPI-04 PET/CT was shown to be superior to 18 F-FDG PET/CT in the evaluation of malignant mixed germ cell testicular tumor metastases.

Incidental Detection of a Type B3 Thymoma on 68Ga-FAPI-04 PET/CT Imaging.

ABSTRACT: 18F-FDG PET/CT performed for staging of colon cancer in a 60-year-old woman revealed a thymic neoplasm with increased radiopharmaceutical uptake in the anterior mediastinum. 68Ga-FAPI PET/CT showed low FAPI uptake in the anterior mediastinal mass. The patient was diagnosed with type B3 thymoma by histopathologic evaluation. In this case, thymoma demonstrated lower uptake with FAPI than FDG. Larger studies are required for the differentiation of malignant and benign mediastinal masses with FAPI.

The role of basal metabolic and volumetric 18F-FDG PET/CT parameters and their changes in predicting pathological complete response in breast cancer patients receiving neoadjuvant chemotherapy.

OBJECTIVE: The aim of this study is to investigate the roles of pre- and post- treatment quantitative fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) parameters including maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) and their rate of change in predicting pathological complete response (pCR) in patients with local and locally advanced invasive breast cancer receiving neoadjuvant chemotherapy (NAC). SUBJECTS AND METHODS: Ninety-eight patients who received NAC after being diagnosed with local and locally advanced invasive breast cancer between January 2017 and September 2021 were retrospectively included in our study. Molecular subtypes of all patients were determined. Maximum SUV, MTV, TLG, percent change in SUVmax (ΔSUVmax), ΔMTV, and ΔTLG obtained from PET/CT scans performed before and after NAC were calculated. The cut-off, AUC, sensitivity, and specificity values of these parameters in predicting pCR were calculated using receiver operating characteristic (ROC) curves. RESULTS: ΔTMTV (cut-off 94.01%, AUC: 0.846), ΔTTLG (cut-off 97.36%, AUC: 0.870), B2MTV (cut-off<1.75, AUC: 0.764), B2TLG (cut-off<2.11, AUC: 0.764), B2SUVmax (cut-off<1.58, AUC: 0.767), ΔBMTV (cut-off 93.67%, AUC: 0.851), ΔBTLG (cut-off 97.22%, AUC: 0.870), ΔBSUVmax (cut-off 84.99%, AUC: 0.846) calculated using ROC curves were found to significantly predict pCR with high sensitivity and specificity. CONCLUSION: We concluded that metabolic and volumetric PET/CT parameters, the rates of their change, and metabolic response during NAC may be important variables in predicting pCR in patients with breast cancer.

Comparison of 18 F-FDG PET/CT and 68 Ga-FAPI-04 PET/CT in patients with non-small cell lung cancer.

AIM: In this study, we aimed to compare the diagnostic accuracy of 18 F-fluorodeoxyglucose ( 18 F-FDG) and Gallium-68 labeled fibroblast activator protein inhibitor ( 68 Ga-FAPI)-04 PET/CT in the tumor-node-metastasis (TNM) staging of patients with nonsmall cell lung cancer (NSCLC) and investigate whether adenocarcinoma (ADC) and squamous cell cancer (SCC) exhibit different uptake patterns on 68 Ga-FAPI-04 PET/CT. MATERIALS AND METHOD: Twenty-nine patients with a histopathologically-confirmed diagnosis of NSCLC, who had no history of previous radiation therapy or chemotherapy and underwent 18 F-FDG PET/CT and 68 Ga-FAPI-04 PET/CT imaging between January 2021 and December 2021 were included in this retrospective study. Staging was performed using the 8th edition of the TNM staging system on both 18 F-FDG PET/CT and 68 Ga-FAPI-04 PET/CT images. Standardized uptake value (SUV) max and tumor-to-background ratios (TBR) were calculated on primary lesions and metastases. RESULTS: There was no statistically significant difference in primary lesions in terms of SUV max and TBR values. However, 68 Ga-FAPI-04 PET/CT was significantly superior to 18 F-FDG PET/CT in terms of the number of lymph nodes and bone metastases revealed. The SUV max and TBR values of lymph nodes, hepatic lesions and bone lesions were significantly higher on 68 Ga-FAPI-04 PET/CT than on 18 F-FDG PET/CT. 68 Ga-FAPI-04 PET/CT changed the disease stage of three patients (10.9%). The diagnostic accuracy of 68 Ga-FAPI-04 PET/CT was 100%, whereas the diagnostic accuracy of 18 F-FDG PET/CT was 89.6% ( P = 0.250). CONCLUSION: Although 68 Ga-FAPI-04 PET/CT detected more lesions and higher diagnostic accuracy than 18 F-FDG PET/CT in NSCLC, neither method was statistically superior to each other in terms of diagnostic accuracy in TNM staging.

Perirenal Infiltration of Signet Ring Cell Colon Carcinoma Shown by 68Ga-FAPI PET/CT.

ABSTRACT: A soft tissue lesion surrounding the left kidney was detected in 18F-FDG PET/CT performed with suspicion of recurrence in a patient who was operated for descending colon cancer and showed mild FDG uptake. Intense fibroblast activation protein-specific inhibitor (FAPI) uptake in the perirenal soft tissue was observed in 68Ga-FAPI-04 PET/CT. Tru-cut biopsy of the left perirenal lesion revealed signet ring cell colon carcinoma metastasis. This case demonstrated that 68Ga-FAPI-04 PET/CT could be a promising radiopharmaceutical for the evaluation of signet ring cell colon carcinomas.

Comparison of [68 Ga]Ga-DOTA-FAPI-04 PET/CT and [18F]FDG PET/CT in colorectal cancer.

AIM: In this study, we aimed to evaluate the diagnostic sensitivity of [68 Ga]Ga-DOTA-FAPI-04 PET/CT in the evaluation of primary or recurrent tumor, and nodal, peritoneal, and distant organ metastases in patients with newly diagnosed or relapsed colorectal cancer (CRC) in comparison with [18F]FDG PET/CT. MATERIALS AND METHOD: Thirty-nine patients with histopathologically confirmed primary or relapsed CRC were included in our study. All patients underwent both [18F]FDG and [68 Ga]Ga-DOTA-FAPI-04 PET/CT imaging in the same week. Primary lesions, lymph nodes, and metastatic lesions were recorded on both scans. SUVmax and background values were measured from the primary and metastatic lesions; tumor-to-background ratio (TBR) was calculated and compared. The results of the operation were compared with PET findings in patients who underwent surgical treatment without neoadjuvant chemotherapy (NAC). RESULTS: The sensitivity and specificity of [68 Ga]Ga-DOTA-FAPI-04 PET/CT in the evaluation of primary tumors were 100%, while the sensitivity of [18F]FDG PET/CT was 100% and its specificity was 85.3%. When evaluated with surgical results in the detection of lymph nodes, [68 Ga]Ga-DOTA-FAPI-04 PET/CT had a sensitivity of 90% and a specificity of 100%, whereas [18F]FDG PET/CT had a sensitivity of 80% and a specificity of 81.8%. The sensitivity and specificity of [68 Ga]Ga-DOTA-FAPI PET/CT for peritoneal implants were 100%, and the sensitivity of [18F]FDG PET/CT was 55%. The SUVmax of primary lesions was higher with [18F]FDG (p < 0.001), while TBR was higher in [68 Ga]Ga-DOTA-FAPI PET/CT than [18F]FDG PET/CT (p: 0.008). SUVmax and TBR of the lymph nodes were significantly higher in [68 Ga]Ga-DOTA-FAPI PET/CT than [18F]FDG PET/CT (p < 0.001 for both). CONCLUSION: [68 Ga]Ga-DOTA-FAPI-04 PET/CT achieved much higher sensitivity and specificity in the detection of primary lesions, and especially the lymph nodes and peritoneal metastases, suggesting that it can be employed in the assessment of primary tumor and metastases in patients with CRC in routine clinical practice.

Comparison of 18F-FDG PET/CT and 68Ga-FAPI-04 PET/CT in the staging and restaging of gastric adenocarcinoma.

OBJECTIVE: In this study, we aimed to evaluate the diagnostic sensitivities of 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT in the primary tumor, and nodal, peritoneal and distant organ metastases of primary and recurrent gastric adenocarcinoma (GAc) with patient and lesion-based comparison. MATERIALS AND METHOD: Twenty-one patients with histopathologically proven newly diagnosed or recurrent GAc who underwent 18F-FDG and 68Ga-FAPI-04 imaging were included in the study. Both imaging techniques were evaluated visually according to the intensity of organ-based uptake. SUVmax and tumor-to-background ratio (TBR) values obtained from primary tumor/relapse and metastatic organs were compared statistically. RESULTS: 68Ga-FAPI-04 uptake was positive in all 15 newly diagnosed patients, while two patients among them who had mucinous and signet ring cell carcinoma did not exhibit 18F-FDG uptake. The sensitivity and specificity of 68Ga-FAPI-04 PET/CT in detecting primary gastric were 100%, while the sensitivity and specificity of 18F-FDG were 86.6 and 100%, respectively. 68Ga-FAPI-04 imaging revealed diffuse stomach uptake in seven patients, while 18F-FDG could only show two of them. The sensitivity and specificity of in-patient-based detection of lymph node metastases were 100 and 95.2%, respectively, while these values were 71.4 and 93.7%, respectively, for 18F-FDG. For peritoneal involvement 68Ga-FAPI-04 had a sensitivity and specificity of 100%, whereas 18F-FDG had a sensitivity of 40% and a specificity of 100%. CONCLUSION: 68Ga-FAPI-04 PET/CT is an imaging modality with the potential of yielding more sensitive and specific findings 18F-FDG PET/CT. This modality may help avoid invasive diagnostic procedures that may be frequently required in GAc.

68Ga-FAPI-04 PET/CT Versus 18F-FDG PET/CT in Malignant Peritoneal Mesothelioma.

ABSTRACT: An 83-year-old man presented with abdominal pain, vomiting, and bloating. His abdominal CT revealed heterogeneous peritoneal thickening in the lower quadrants, which was more prominent in the pelvic region. 18F-FDG PET/CT performed to locate the primary tumor showed irregular peritoneal and omental thickening with low to moderate FDG uptake. 68Ga-FAPI (fibroblast activation protein-specific inhibitor)-04 PET/CT of the patient, whose primary tumor could not be detected using FDG, showed high radiopharmaceutical uptake in the areas of heterogeneous thickening on peritoneal and serosal surfaces. Peritoneal Tru-Cut biopsy revealed malignant tumoral infiltration indicating mesothelioma. This case showed that 68Ga-FAPI-04 PET/CT could be a promising radiopharmaceutical in the evaluation of peritoneal mesothelioma.

FAPI-04 Uptake in Healthy Tissues of Cancer Patients in 68Ga-FAPI-04 PET/CT Imaging.

Objective: The aim of this study is to investigate the uptake of 68Ga-FAPI-04 in normal tissues and calculate standardized uptake values (SUVs) for various organs in the body. Methods: A total of 49 patients who underwent 68Ga-FAPI-04 PET/CT were included in our study. The following organs were identified on CT images: brain, parotid, and submandibular glands, palatine tonsils, thyroid, lymph nodes (if present), breasts, lungs, thymus, left ventricle walls, mediastinal blood pool, vertebral bone marrow, liver, spleen, pancreas, stomach, small and large intestines, adrenal glands, kidneys, uterus, testes, and prostate. Median, minimum, and maximum values (max) and average (avg) values of standard uptake value (SUV) of tissues and organs were calculated. Results: The accumulation of 68Ga-FAPI in normal organs showed variations. The cerebral/cerebellar cortex exhibited no 68Ga-FAPI uptake, while the scalp showed low uptake. Low uptake was also observed in the lung parenchyma, esophagus, left ventricle walls, nipple, and glandular breast tissue. In the abdominopelvic area, the pancreas exhibited low uptake, which was higher in the tail region. Low uptake was observed in the renal cortex. Intense 68Ga-FAPI uptake was observed throughout the uterus, which was higher in the corpus. There was no uptake of 68Ga-FAPI in the bone cortex and medulla. Conclusion: We determined the physiological uptake and SUVmax of FAPI-04 in different tissues and organs and created a guide for researchers.

68Ga-FAPI-04 PET/CT, a new step in breast cancer imaging: a comparative pilot study with the 18F-FDG PET/CT.

AIM: We aimed to compare the roles of 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT in the evaluation of primary tumor and metastases in primary and recurrent breast cancer. MATERIALS AND METHOD: Twenty female patients with histopathologically confirmed primary and recurrent breast cancer were included in the prospective study. All patients underwent FDG and FAPI PET/CT imaging in the same week. The number of primary and metastatic lesions, SUVmax values, and tumor-to-background ratios (TBR) were recorded from both scans. Data obtained were statistically compared. RESULTS: FAPI PET/CT was superior to FDG in detecting breast lesions, as well as hepatic, bone, lymph node, and cerebral metastases in terms of patient- and lesion-based assessments. The sensitivity and specificity of FAPI in detecting primary breast lesions were 100% and 95.6%, respectively, while the sensitivity and specificity of FDG were 78.2% and 100%, respectively. The SUVmax values of primary breast tumors, lymph nodes, lung metastases, and bone metastases were significantly higher on FAPI imaging than FDG imaging (p < 0.05). However, SUVmax values of hepatic metastases did not exhibit a statistically significant difference between two imaging techniques (p > 0.05). Also, FAPI imaging yielded significantly higher TBR in breast lesions as well as hepatic, bone, brain and lung metastases compared to FDG (p < 0.05). CONCLUSION: 68 Ga-FAPI-04 PET/CT is superior to 18F-FDG PET/CT in detecting the primary tumor in patients with breast cancer with its high sensitivity, high SUVmax, and high TBR. 68 Ga-FAPI-04 PET/CT is also superior to 18F-FDG PET/CT in detecting lymph node, hepatic, bone, and cerebral metastases because it has lower background activity and higher uptake in subcentimetric lesions.

68Ga-FAPI Uptake of Thyroiditis in a Patient With Breast Cancer.

ABSTRACT: 68Ga-fibroblast activation protein-specific inhibitor (FAPI)-04 PET/CT was performed in a 49-year-old woman diagnosed with breast cancer. In PET/CT imaging, intense 68Ga-FAPI uptake was observed in the primary tumor, axillary lymph nodes, and also in the thyroid gland, whereas pathological 18F-FDG uptake was not observed in the thyroid gland. On thyroid ultrasonography, parenchyma was heterogeneous, and an area of focal thyroiditis was observed in the superior part of the right lobe. Biochemical parameters were found to be consistent with thyroiditis. This case shows that FAPI uptake in the thyroid gland may be associated with thyroiditis and should be evaluated clinically.