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.

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.

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.

The effect of coronavirus disease 2019 pneumonia on myocardial ischemia detected by single-photon emission computed tomography myocardial perfusion imaging.

OBJECTIVE: We aimed to examine the effects of COVID-19 pneumonia on cardiac ischemia detected by myocardial perfusion imaging with single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) in patients presenting with chest pain and shortness of breath after recovery from COVID-19. MATERIALS AND METHOD: Patients with a history of COVID-19 confirmed by reverse transcriptase-PCR test who underwent SPECT-MPI for the evaluation of ischemia with the complaints of chest pain and shortness of breath were screened for this study. Patients who underwent thorax CT during the acute period of the COVID-19 were included. Patients with and without pneumonia were determined based on computed tomographic criteria. The patients with a summed stress score of at least 4 on SPECT-MPI were considered to have abnormal MPI in terms of ischemia. RESULTS: A total of 266 patients were included in the study. Sixty-five (24%) patients had ischemia findings on SPECT-MPI. Thorax CT showed pneumonia in 152 (57%) patients, and the patients were divided into two groups as pneumonia and nonpneumonia. Abnormal SPECT-MPI scores, which represented myocardial ischemia, were higher in the pneumonia group. Multivariate logistic regression analyses showed that the presence of hyperlipidemia and pneumonia on CT increased the risk of ischemia on SPECT-MPI (OR, 2.08; 95% CI, 1.08-3.99; P-value = 0.029; and OR, 2.90; 95% Cl, 1.52-5.54; P-value = 0.001, respectively). CONCLUSION: COVID-19 pneumonia was identified as an independent predictor of ischemia on SPECT-MPI. Symptoms including chest pain and shortness of breath in patients who have had COVID-19 pneumonia may be attributed to coronary ischemia.

The effect of prior COVID-19 infection on coronary microvascular dysfunction.

BACKGROUND: Thrombolysis in Myocardial Infarction Frame Count (TFC) is an index that provides a quantitative evaluation of coronary microvascular dysfunction. In this study, we aimed to examine the effect of COVID-19 infection on TFC in patients admitted with chest pain and dyspnoea after COVID-19 disease and had abnormal findings in myocardial perfusion scintigraphy. METHODS: For this single-center retrospective study, patients with and without a history of COVID-19 who were underwent coronary angiography for abnormal findings in myocardial perfusion scintigraphy between January 1, 2021 and June 30, 2021 were analysed. Patients were divided into two groups as patients with COVID-19 history and those without. After exclusion criteria, patients with adequate angiographic monitoring and data were included in the study. RESULTS: A total of 210 patients, 48 with a history of COVID-19, were included in the study. The mean age was ±55 10 years, and 122 (58%) patients were women. In patients with a history of COVID-19, TFC was significantly higher in the LAD (p < 0.001) and LCx (p < 0.001) arteries and RCA TFC (p = 0.223) was similar in both groups. In the linear mix model, male gender (ß = 2.38, 95% CI = 1.26-3.51, p < 0.001) and history of COVID-19 (ß = 1.51, 95% CI = 0.49-2.53, p = 0.004) were significantly associated with TFC. CONCLUSION: TFC may be elevated due to coronary microvascular dysfunction in patients with a history of COVID-19.

SPECT myocardial perfusion imaging identifies myocardial ischemia in patients with a history of COVID-19 without coronary artery disease.

We aimed to examine the effect of a history of COVID-19 on myocardial ischemia in single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) in patients who presented with shortness of breath and/or chest pain after recovery. For this single-center retrospective study, patients who presented at cardiology outpatient clinics and had SPECT-MPI were screened. A total of 1888 patients were included in the study, 340 of whom had a history of COVID-19. 64 patients with > 50% stenosis on coronary angiography were excluded from the study. The primary outcome of the study was abnormal MPI. In the study population, the median age was 56 (49-64 IQR) years, and 1127 (65%) of the patients were female. Abnormal MPI was detected in 77 patients (23%) in the COVID-19 group and in 244 patients (16%) in the non-COVID-19 group. After adjustment was performed for clinical predictors using Bayesian logistic regression, an important association was found between the presence of a confirmed prior COVID-19 infection and abnormal MPI (posterior median odds ratio, 1.70 [95% CrI, 1.20-2.40], risk difference, 9.6% [95% CrI, 1.8%, 19.7%]). In SPECT-MPI, ischemia rates were observed to be higher in COVID-19 group and it was found that a confirmed prior COVID-19 might predict of abnormal MPI.

Comparison of (18F)FDG PET/CT and (68Ga)DOTATATE PET/CT imaging methods in terms of detection of histological subtype and related SUVmax values in patients with pulmonary carcinoid tumors.

OBJECTIVE: This study was designed to compare the 18-Fluorodeoxyglucose positron emission tomography/computed tomography [(F)FDG PET/CT] and 1,4,7,10-tetraazacyclododecane-NI,NII,NIII,NIIII-tetraacetic acid (D)-Phe1-thy3-octreotate [(Ga)DOTATATE PET/CT) findings in patients with pulmonary carcinoid (PC) tumors. MATERIALS AND METHODS: A total of 20 patients [mean (SD) age: 52.2 (12.9) years, 60% women] with PC tumors and available records on digital images of (F)FDG PET/CT and (Ga)DOTATATE PET/CT and histopathological analysis were included in this retrospective single-center study. Patient characteristics, structural and functional imaging, and final histopathology were recorded in all patients. Typical and atypical PC tumors were compared in terms of patient age, tumor site, tumor size, and SUV max values obtained by (F)FDG PET/CT and (Ga)DOTATATE PET/CT imaging. RESULTS: Overall, median (minimum-maximum) SUVmax values were 3.2 (1.2-11.2) in (F)FDG PET/CT and 17.2 (2.5-89.0) in (Ga)DOTATATE PET/CT. Atypical PC tumor was associated with significantly higher mean±SD age (64.6±5.4 vs. 45.5±10.5 years, P=0.036) and median (minimum-maximum) (F)FDG PET/CT SUVmax values [7.3 (4.8-11.2) vs. 2.4 (1.2-3.9), P=0.003], but with significantly lower median (minimum-maximum) (Ga)DOTATATE PET/CT SUVmax values [6.4 (2.5-10.6) vs. 23.7 (14.2-89), P<0.001], compared with typical PC tumor. (F)FDG PET/CT and (Ga)DOTATATE PET/CT SUVmax values were negatively correlated (r=-0.429, P=0.011). CONCLUSION: Our findings in patients with histologically proven PC tumors showed higher SUV max values for (F)FDG PET/CT in atypical PC tumors and for (Ga)DOTATATE PET/CT in typical PC tumors. Our findings indicate the likelihood of higher detection rates particularly for typical PC tumors by (Ga)DOTATATE PET/CT imaging and the potential utility of the SUVmax ratio in predicting the histological subtype of PC tumors.

Contrast Enhanced [99mTc] MIBI SPECT/CT in Primary Hyperparathyroidism.

OBJECTIVE: The aim of the present study was to compare the surgical results with contrast-enhanced [99mTc]methoxyisobutylisonitrile ([99mTc]MIBI) single-photon emission computed tomography (SPECT)/computed tomography (CT) results by adding the simultaneous single phase contrast to the [99mTc]MIBI SPECT/CT examination. METHOD: Between November 2016 and January 2018, 24 (21 female, 3 male) patients who underwent an operation after preoperative contrast-enhanced [99mTc]MIBI SPECT/CT, and 49 asymptomatic patients (42 female, 7 male), who did not undergo surgery, were included in the study. RESULTS: Sensitivity and specificity rates of contrast enhanced [99mTc]MIBI SPECT/CT were 100% and 100% when evaluated together with surgical results. The rate of detection in asymptomatic patients was found to be 93.8%. CONCLUSIONS: With the contrast-enhanced [99mTc]MIBI SPECT/CT imaging, both high sensitivity and specificity values were achieved in the preoperative localization of parathyroid adenomas (PTAs) and high detection rates were obtained in the asymptomatic group. The use of contrast IV during the [99mTc]MIBI SPECT/CT in patients without contraindications increased both preoperative localization rates of adenomas and detection rates of asymptomatic hyperparathyroidism cases. KEY WORDS: Parathyroid adenoma, Primary Hyperparathyroidism, [99mTc]MIBI, SPECT/CT.

Insufficiency of bone scintigraphy in vertebral lesions of langerhans cell histiocytosis compared to f-18 fluorodeoxyglucose positron emission tomography/computed tomography and diagnostic computed tomography.

Langerhans cell histiocytosis (LCH) is a benign disorder related to the histiocytes which can infiltrate bone tissue. The most effective method for demonstrating severity of this disease is PET/CT and bone scintigraphy might show bone lesions. We present a seventeen year old male patient with disseminated LCH presented with exophtalmos and having multiple vertebral lesions which were identified by F-18 FDG PET/CT scan and diagnostic CT but not in the bone scintigraphy.

Classical vs. unit area method in the evaluation of differential renal function in unilateral hydronephrosis.

BACKGROUND: There are some problematic results in determination of differential renal function (DRF) by means of Tc-99m DMSA renal scintigraphy in hydronephrotic kidneys. In this study the classical method (CM) and unit area methods (UAM) in the estimation of DRF in unilateral hydronephrosis before and after intervention were compared. METHODS: Twenty patients (12 M, 8 F; mean: 42.6±18.5 years old) who were candidates for surgery or intervention because of unilateral hydronephrosis were the subjects of this study. All the patients were evaluated by Tc-99m DMSA scintigraphy before and 3-6 months after the intervention. In order to estimate DRF both CM and UAM (obtained by division of the counts including the kidney ROI to pixel of the same ROI) were performed. Bland-Altman analyses were performed in order to compare the DRF values obtained from both methods. RESULTS: The agreement between CM and UAM was poor in the preoperative estimation, however, the agreement was good after the operation or intervention. CONCLUSIONS: In this study it seems that DRF estimation with CM in unilateral hydronephrosis might be problematic in the determination of surgery thus UAM might be introduced as the method of choice in the determination of DRF in unilateral hyronephrosis.