Marina Orevi

68Ga-DOTA-NOC PET/CT Imaging of Neuroendocrine Tumors: Comparison with 111In-DTPA-Octreotide (OctreoScan®)

PurposeRecent data have indicated that 68Ga-DOTA-NOC positron emission tomography/X-ray computed tomography (PET/CT) may yield improved images in a shorter acquisition protocol than 111In-DTPA-octreotide (OctreoScan®, OCT). Therefore, we performed a prospective comparison of 68Ga-DOTA-NOC and OCT for the detection of neuroendocrine tumors (NETs).MethodsNineteen patients (eight carcinoid, nine pancreatic NETs, and two NE carcinoma of unknown origin) with previous positive OCT scans underwent 68Ga-DOTA-NOC PET/CT and OCT single-photon emission computed tomography imaging for staging or follow-up. Findings were compared by region and verified with conventional imaging.ResultsAll images of both modalities demonstrated focal uptake, often at multiple sites. 68Ga-DOTA-NOC images were clearer than OCT images, facilitating interpretation. Similar foci were identified with both modalities in 41 regions, with additional foci on 68Ga-DOTA-NOC in 21 and on OCT in 15 regions. CT, magnetic resonance imaging, or ultrasound confirmed the concordant findings in 31 of 41 regions and findings seen with 68Ga-DOTA-NOC only in 15 of 21 regions. Findings seen with OCT only were less clear and were only confirmed in 4 of 15 regions. 68Ga-DOTA-NOC had impact on staging in four patients and on management in three patients.ConclusionsAlthough 68Ga-DOTA-NOC and OCT images were similar, in this study, 68Ga-DOTA-NOC demonstrated more true positive tumor foci and was better tolerated by patients. This direct comparison supports replacement of OCT with 68Ga-DOTA-NOC-PET/CT in the evaluation of NETs.

18F-Fluorodeoxyglucose-PET/CT Imaging of Lungs in Patients With Cystic Fibrosis

BACKGROUND Airway inflammation plays a critical role in the progression of cystic fibrosis (CF) lung disease, and in the destruction of airways and lung parenchyma. Current methods to assess CF lung disease (BAL, spirometry, and high-resolution CT scanning), do not always accurately reflect actual disease states. Fluorodeoxyglucose (FDG)-PET scanning has been used previously to image infection and inflammation. In this study, we assessed the use of (18)F-FDG PET/CT scanning to evaluate and monitor lung inflammation and/or infection in patients with CF. METHODS PET/CT scans were performed in 20 patients with CF (age range, 14 to 54 years); 7 of 20 patients underwent repeat PET/CT scans during and after acute exacerbations. The results were compared with clinical information and with images from eight control subjects with no known lung disease. RESULTS Foci of enhanced activity were observed on FDG-PET scans of patients with CF but not those of control subjects. Higher focal activity (standardized uptake value, > 3.0) was seen during disease exacerbation and infection. Coregistered CT scan images assisted in the localization of PET foci and showed corresponding CT scan findings, with many additional findings on CT scans that were not seen on PET scans. Foci seen on high-intensity PET scans during exacerbations disappeared after antibiotic therapy and the resolution of exacerbation, while corresponding CT scan findings remained unchanged. CONCLUSIONS PET/CT imaging demonstrated the presence of foci of enhanced uptake that may reflect active focal infectious or inflammatory processes in the lungs. These foci can be cleared with antibiotic therapy. Further studies are needed to validate these results and to determine whether FDG-PET/CT scanning can predict the nature/severity of disease in patients with CF.

11C-acetate PET/CT in bladder urothelial carcinoma: intraindividual comparison with 11C-choline.

Objective: We present a first study of the use of 11C-acetate (ACET) positron emission tomography (PET)/computed tomography (CT) in bladder urothelial carcinoma (UC) and an intraindividual comparison with 11C- choline (CHOL) PET/CT. Methods: Fourteen patients with biopsy-proven UC (11 T2, 3 T1 refractory to treatment) were prospectively evaluated before radical cystectomy and excision of pelvic lymph nodes (LNs), with ACET and CHOL PET/CT scans performed within 1 week. Image acquisition started 5 minutes after intravenous injection of 12 to 14 mCi for both tracers. Standardized uptake values (SUVs) and tumor-to-background ratios (TBR) were calculated for all tumor and nodal findings and correlated with histopathology and follow-up. Results: ACET and CHOL were taken up in all UCs, involved LNs, and prostate pathology. SUVs were on average slightly, nonsignificantly higher for CHOL uptake (SUV) in UCs and significantly higher for ACET in LNs. TBR was nonsignificantly higher with CHOL for UC and significantly higher for LNs. Conclusions: In this preliminary series, 11C-ACET and 11C-CHOL PET/CT showed equivalent results in the preoperative evaluation of UC. Both tracers have the potential to contribute to selecting patients who would benefit from combined treatment—neoadjuvant chemotherapy and surgery—by identifying pathologic LNs or from surgery only, thanks to their high negative predictive value for LN involvement.

Localization of parathyroid adenoma by ¹¹C-choline PET/CT: preliminary results.

Purpose This prospective pilot study was aimed to evaluate 11C-choline PET/CT (choline) as a tool for localization of parathyroid adenoma (PTA). Methods Forty patients with biochemical hyperparathyroidism underwent choline and 99mTc-MIBI imaging within a median interval of 56 days. Choline and MIBI images were analyzed and correlated with each other, with additional modalities such as ultrasound, CT, MRI, and with surgical findings, when available. Results Thirty-seven of forty cases were choline-positive, and 3 were choline-negative. Choline uptake on PET was identified with corresponding nodules on CT of the PET/CT, yielding precise localization. Twenty of thirty-seven foci were located in typical sites in the neck, and 17 were ectopic. Clear visualization of PTA was achieved in 33 of 37, whereas findings in 4 cases were suspicious for PTA. MIBI was positive in 33 of 40 cases (22 clearly positive, 11 suspicious). In 29 of 40 cases, choline and MIBI were concordant, but choline findings were clearer in 9 of these 29 studies. At the time of writing, 27 patients had undergone surgery. In 24 cases, there was complete matching of choline with surgical findings of PTA. Overall in 23 cases, both choline and MIBI matched surgical findings of PTA. In 1 case, PTA was correctly localized on choline but not on MIBI, and in 2 cases, neither choline nor MIBI corresponded to the surgical findings. Conclusions These preliminary results indicate that the combined functional and anatomical modality of choline PET/CT is a promising tool for PTA localization, providing clearer images than MIBI, equal or better accuracy, and quicker and easier acquisition.

Ga-68 DOTA-NOC uptake in the pancreas: pathological and physiological patterns.

Objective: Gallium-68 (Ga-68) DOTA-1-NaI3-octreotide (DOTA-NOC) positron emission tomography (PET)/computed tomography (CT) is increasingly used for neuroendocrine tumors (NETs), often found primarily in the pancreas. However, physiologic uptake of DOTA-NOC has been described in the uncinate process of the pancreas. We studied DOTA-NOC uptake in this organ. Materials and Methods: Ninety-six patients underwent 103 DOTA-NOC scans, with pathology-proven pancreatic NET (n = 40) and nonpancreatic NET or biochemical suspicion of NET (n = 63). Results: DOTA-NOC uptake was detected in 35 documented pancreatic tumor sites (SUV: 5.5–165; mean: 25.7 ± 28.8; median: 17.8). Among 63 cases without previous known pathology, uptake was suspicious for tumor in 24 sites (SUV: 4.7–35; mean 16.3 ± 8.0; median: 14.1), and in 38 sites, it was judged as physiological, generally lower relative to adjacent structures (SUV: 2.2–12.6; mean: 6.6 ± 2.2; median: 6.2). In 24 scans with suspected tumor and in 37 of 38 scans with physiological uptake, diagnostic computed tomography or magnetic resonance imaging or endoscopic ultrasonography failed to detect tumor. Conclusions: Pancreatic DOTA-NOC uptake must be interpreted with caution, and further studies are required.

PET/CT With 68Ga-DOTA-TATE for Diagnosis of Neuroendocrine: Differentiation in Patients With Castrate-Resistant Prostate Cancer.

Aim Castrate-resistant prostate cancer (CRPC) often shows histological evidence of neuroendocrine differentiation (NED). To evaluate the extent of NED in patients with CRPC, we used PET/CT with 68Ga-[DOTA-Tyr3]-octreotate (68Ga-DOTA-TATE), a somatostatin analog that binds somatostatin receptor 2 with high affinity. This radiotracer is used in imaging of neuroendocrine tumors. Methods Twelve patients (mean age, 65 [SD, 12] years) with CRPC were studied. Their mean prostate-specific antigen level at scanning was 85.6 (SD, 144.6) ng/mL. PET/CT images were obtained after the injection of 120 to 200 MBq of 68Ga-DOTA-TATE. Results All participants had at least 1 blastic metastasis demonstrating uptake of 68Ga-DOTA-TATE (mean SUVmax of 5.3 [SD, 2.3]). In 6 patients, moderately high to high uptakes (SUVmax, >5) were seen. Patients with multiple bone metastases had a significantly higher SUVmax compared with patients with few metastases (mean of 5.8 vs 3.8, P = 0.05). In 4 patients, lytic bone lesions or lymph node metastases also showed uptake of the tracer (mean SUVmax of 7.2 [SD, 3.2]). Uptake of the radiotracer was also observed in bones showing normal architecture in CT, suggesting that NED cells appear early during metastases development. Conclusions Uptake of 68Ga-DOTA-TATE is a common finding in metastases of CRPC patients, suggesting that NED is frequent in these patients. In half of the patients, widespread uptake of 68Ga-DOTA-TATE was observed. This suggests that the possibility of treating selected CRCP patients with anti–neuroendocrine tumor therapies should be explored and that 68Ga-DOTA-TATE scanning could have a role in predicting the efficacy of these treatments.

A case of metastatic adamantinoma responding to treatment with pazopanib.

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Is 18F-FDG PET/CT an accurate tool for identifying metastases of lobular breast cancer?

Invasive lobular breast cancer (IlBrCa) accounts for only about 8–14% of a heterogeneous group of different histological types of breast cancer (BrCa), but it is still not infrequent due to high overall incidence of BrCa and an increasing rate of this type of tumor in older women since 1977 [1]. BrCa has a well known glycolytic activity due to overexpression of glucose transporters [2] that make F-18-fluorodeoxyglucose (FDG) a suitable tracer, and BrCa one of the frequent indications for PET/CT [3]. significantly lower FDG uptake has been demonstrated in primary IlBrCa versus invasive ductal BrCa (IDBrCa) [4,5], with false negative rates of up to 66% for IlBrCa. a logical resulting extrapolation is that FDG uptake may be also low in metastasis of IlBrCa. This raises an important question regarding the relevance of FDG positron emission tomography/ computerized tomography (PET/CT) for follow-up of IlBrCa. However, despite this common assumption, to the best of our knowledge, little clinical data has been reported to date on this issue. In this study we set out to examine whether metastases of IlBrCa have lower FDG avidity similarly to the primary tumor, and thus whether FDG may be appropriate for systemic evaluation of patients with IlBrCa.