Metin Halac

Evaluation of PSMA PET/CT imaging using a 68Ga-HBED-CC ligand in patients with prostate cancer and the value of early pelvic imaging.

PurposeThe aim of the study was to evaluate the diagnostic value of the prostate-specific membrane antigen (PSMA) ligand 68Ga-HBED-CC (PSMA PET/CT) in patients with prostate cancer and evaluate the value of early imaging of the pelvis. Materials and methodsThe files of 28 patients were retrospectively evaluated. All patients had a histopatological confirmation of prostate cancer. PSMA PET/CT images were obtained at 5 and 60 min after injection from all patients. ResultsIntense pathologic radiotracer uptake was observed in 23 patients (77%) at the site of primary tumour. Lymph node metastases were detected in 10 patients (36%) and bone metastases were detected in seven patients (25%). Bone scan (n=25) results revealed metastatic bone lesions in four patients, equivocal results in nine patients and normal results in 12 patients. PSMA PET/CT confirmed bone metastases in all four patients. Pathologic radiotracer uptake in PSMA PET/CT scans was observed only in one patient among those who had equivocal bone scans. PSMA PET/CT showed additional bone lesions in two patients who had a normal bone scan. When we compared early and late pelvic images we found no difference in the number of lesions detected. The maximum standardized uptake value (SUVmax) for primary tumour, lymph nodes and bone metastases was significantly higher in late images. ConclusionPSMA PET/CT imaging seems to be a valuable imaging modality for evaluation of primary prostate cancer and it seems to have potential for the detection of lymph node and bone metastases. Early images 5 min p.i. can help to better distinguish between urinary bladder (before tracer accumulation occurs) and tumour lesions.

68 Ga-PSMA PET/CT imaging of metastatic clear cell renal cell carcinoma

Prostate-specific membrane antigen (PSMA) is a type II transmembrane protein with high expression in prostate carcinoma cells. Glu-NH-CO-NH-Lys-(Ahx)-[Ga(HBED-CC)] (GaPSMA) has been suggested as a novel tracer that can detect prostate carcinoma relapses and metastases with high contrast by targeting PSMA [1]. Besides prostate cancer, PSMA has been shown to be expressed in the neovasculature of various solid malignant tumours including clear cell renal cell carcinoma (ccRCC) [2, 3]. RCC is a potentially lethal cancer with aggressive behaviour, and has a propensity for distant metastatic spread. The common sites of metastases from ccRCC include lungs (33 – 72 %), intraabdominal lymph nodes (3 – 35 %) and brain (7 – 13 %) [4]. Bone metastases are also a frequent complication in patients with ccRCC [4]. We present to our knowledge the first reported case of a patient with a diagnosis of ccRCC with Ga-PSMA uptake. A 65-yearold woman, status post-nephrectomy, underwent GaPSMA (b) and F-FDG (a) PET/CT for staging. GaPSMA PET/CT showed multiple pathological bone lesions with intense uptake of the tracer in the seventh cervical vertebra and acromion of the left scapula (c, d, e; SUVmax=35 for PSMA, 7.2 for FDG), sternum (f, g, h; SUVmax=28.3 for PSMA, 5.15 for FDG), and right tuber ischiadicum (i, j, k; SUVmax 34.1 for PSMA, 5.3 for FDG). F-FDG PET/CT provided lower visual detectability of the bone metastasis. This case indicates the clinical utility of Ga-PSMA for the imaging of RCC.

The additional value of FDG PET imaging for distinguishing N0 or N1 from N2 stage in preoperative staging of non-small cell lung cancer in region where the prevalence of inflammatory lung disease is high.

Purpose: The aim of this study was to evaluate the efficacy of PET imaging and compare it with the performance of CT in mediastinal and hilar lymph node staging in potentially operable non-small cell lung cancer (NSCLC). Methods: Fifty-nine patients with potentially resectable NSCLC who underwent preoperative PET and CT imaging were enrolled into this prospective study. All patients underwent surgical evaluation by means of mediastinoscopy with mediastinal lymph node sampling (14 patients) or thoracotomy (45 patients). Results: The prevalence of lymph node metastases was 53%. Overall, the sensitivity, specificity, accuracy, PPV, and NPV of PET were 79%, 76%, 78%, 86%, and 76% for N0 and N1 lymph nodes and 76%, 79%, 80%, 67%, and 83% for N2 lymph nodes, while those values for CT were 66%, 43%, 58%, 68%, and 43% for N0 and N1 stations and 43%, 66%, 54%, 41%, and 66% for N2 lymph nodes, respectively. PET correctly differentiated cases with mediastinal lymph node involvement (N2) from those without such involvement (N0 or N1) in 76% of cases. Statistical analysis of the diagnostic accuracy of nodal involvement showed that PET improves diagnostic accuracy significantly in the detection of both N0 or N1 and N2 status in the individual patient based on analysis, compared with CT (P < 0.01 and P < 0.01, respectively). When preoperative nodal staging was compared with postoperative histopathological staging, 38 (65%) patients were correctly staged, 9 (15%) were overstaged, and 12 (20%) were understaged by PET, while 29 patients (49%) were correctly staged, 13 (22%) were overstaged, and 17 (29%) were understaged by CT. Conclusion: It has been clearly shown that PET is more accurate than CT for the differentiation of N0 or N1 from N2 disease in patients with NSCLC. However, PET imaging alone does not appear to be sufficient to replace mediastinoscopy for mediastinal staging in patients with lung cancer, especially in geographic regions with high granulomatous or inflammatory mediastinal disease prevalence.

Standardized Uptake Values of Normal Organs on 18F-Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography Imaging

Standardized uptake values (SUVs) of normal organs were evaluated by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography and computed tomography (PET-CT) scanning. Seventy patients (38 men and 32 women) with no non-physiological 18F-FDG uptake participated in the study. All patients fasted for at least 4 h before PET-CT imaging and their fasting blood glucose levels were within the normal range. Image acquisition was performed after intravenous administration of 18F-FDG and images were obtained from the vertex to the upper thigh region. The SUVs of various organs were determined from the transverse views. The uptake of 18F-FDG was highest in the cerebrum, cerebellum, myocardium, tonsils, liver and spleen in both sexes. Having knowledge of the physiological uptake of 18F-FDG and normal organ SUVs is required for the correct interpretation of whole-body 18F-FDG-PET-CT studies.

Detection of Metastases in Patients with Cutaneous Melanoma Using FDG-PET/CT

This study aimed to detect metastases in patients with stage III or IV cutaneous melanoma by 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT). Thirty-nine patients with clinically evident stage III or IV melanoma underwent whole-body FDG-PET/CT scans for metastatic disease and these results were compared with those of biopsy. Scans for 38 of the patients were evaluated; one patients scan could not be evaluated. There were 11 true-positive, two false-positive, 24 true-negative and one false-negative scans for the detection of melanoma metastases, with sensitivity 91%, specificity 92%, accuracy 92%, and positive and negative predictive values 84% and 96%, respectively. False-positive FDG-PET/CT scans were due to sarcoidosis in the lung and infected cyst in the liver. It is concluded that FDG-PET/CT scanning has high sensitivity and specificity for detecting stage III or IV metastatic melanoma.

Correlation of 18F-fluorodeoxyglucose uptake with histopathological prognostic factors in breast carcinoma.

ObjectiveThis study investigated the prognostic value of [18F]-fluorodeoxyglucose (18F-FDG) uptake in breast carcinomas by comparing 18F-FDG PET/computed tomography (CT) images with histopathological and immunohistochemical prognostic factors. MethodsThis study included 136 women and four men with positive biopsy breast carcinomas who underwent 18F-FDG PET/CT imaging for initial staging. Maximum standardized uptake values (SUVmax) and tumour-to-background SUVmax ratios were calculated and compared with histopathological and immunohistochemical tumour characteristics, patient properties and axillary lymph node involvement. Calculations of SUVmax for men were performed separately. ResultsFor the tumours in women, the mean SUVmax was 10.06±6.91 and the median SUVmax was 9.05 (0.7–35.0). Primary tumour 18F-FDG uptake and tumour-to-background SUVmax ratios were correlated with tumour size (P<0.001), histological type (P<0.001), histological grade (P=0.004), pleomorphism (P=0.010), mitosis count (P<0.001), lymphatic invasion (P=0.009), necrosis (P=0.005), oestrogen negativity (P=0.004), high Ki-67 level (P<0.001), axillary lymph node involvement (P<0.001) and triple negativity (P=0.002). High Ki-67 level (odds ratio=16; 95% confidence interval=1.6–160; P=0.016) and tumour size (odds ratio=4; 95% confidence interval=1.5–11; P=0.007) were determining factors for high 18F-FDG uptake values. Other clinicopathological and immunohistopathological parameters including progesterone receptor (P=0.211), CerbB2 overexpression (P=0.170), perineural invasion (P=0.053), intratumoural calcification (P=0.438), desmoplasia (P=0.112), tubular formation (P=0.768) and age (P=0.675) were not significantly correlated with 18F-FDG uptake. No significant relationship was observed between the tumour/contralateral breast SUVmax ratio and mitotic count, oestrogen receptor status or triple negativity. Conclusion18F-FDG uptake may serve as a prognostic indicator for biological behaviour in breast tumours.

Radioguided occult lesion localization (ROLL) for non-palpable breast cancer: A comparison between day-before and same-day protocols

BACKGROUND Although radioguided occult lesion localization (ROLL) has become a widely accepted technique, the optimal time interval between the radioisotope injection and surgery has not yet been determined. AIM To delineate the effects of time from the injection of the radionuclide until surgery on the ROLL success rate in a patient population diagnosed as having non-palpable breast cancer. METHODS Between December 2004 and May 2009, 75 patients underwent ROLL procedure. The day-before protocol and same-day protocols included 50 and 25 breast cancer patients respectively. RESULTS The two study groups were comparable in terms of age, localization technique, radiological findings and the type of surgical procedures (P > 0.05). No statistically significant difference was noticed in the pathological diagnosis, cancer size and the surgical margin clearance between the two groups (P > 0.05). CONCLUSIONS Same-day injection of the radiotracer was not superior to the day-before injection in ROLL. The day-before protocol can be scheduled for the convenience of both patients and hospital staff.

A doughnut sign of a hydatid cyst of the liver on F-18 FDG PET/CT.

A 59-year-old man underwent a whole-body PET/CT scan to evaluate the metabolic activity of a nodule in the upper lobe of the left lung seen on CT. Slightly increased peripheral activity with a large hypometabolic region centrally, a so-called doughnut sign, was seen in the right lobe of the liver. After the diagnosis of a hydatid cyst of the liver, the patient underwent surgery. This case demonstrates a hydatid cyst that caused increased F-18 FDG uptake as a doughnut pattern.

Avoidance of misinterpretation of an FDG positive sacral insufficiency fracture using PET/CT scans in a patient with endometrial cancer: a case report.

Whole-body FDG PET is an important tool for imaging of cancer, including skeletal metastases. However, false-positive results can occur in benign diseases such as insufficiency fractures. We report a case of sacral insufficiency fracture in which increased FDG uptake was detected. Correlative CT images obtained by a combined PET/CT scanner excluded a possible false-positive interpretation by revealing the fracture lines at the site of increased FDG uptake.

Positron emission tomography/computed tomography imaging of brown tumors mimicking multiple skeletal metastases in patient with primary hyperparathyroidism

Brown tumors of bone are highly vascular, lytic bone lesions representing a reparative cellular process rather than a neoplastic process usually seen in patients with hyperparathyroidism. These tumors can behave aggressively and be destructive. We report a 49-year-old male patient who was admitted to our hospital with a long-term history of right shoulder and right hip pain. Multiple lytic and destructive bone lesions were found in X-ray graphy and CT images. These bone lesions mimicked multiple skeletal metastatic lesions and seemed to be those of the terminal stage of malignancy. PET scan was requested for the evaluation of FDG uptake of these lesions and to search the unknown primary tumor site. Positron emission tomography/computed tomography (PET/CT) images showed multiple hypermetabolic malignant or metastatic FDG avid bone lesions in skeletal system. However the biopsy results revealed no signs of malignancy and laboratory data showed elevated serum calcium, alkaline phosphatase, parathyroid hormone, low serum phosphate and parathyroid scintigraphy was performed. Adenoma in the left parathyroid gland was seen with Tc-99m MIBI parathyroid scintigraphy. Pathological results confirmed the diagnosis of parathyroid adenoma. Brown tumor is the potential cause of false-positive result in evaluation of a patient for unknown primary tumor or skeletal metastases with PET/CT imaging.