Role of (68)Ga somatostatin receptor PET/CT in the detection of endogenous hyperinsulinaemic focus: an explorative study.

PURPOSE: To explore the role of (68)Ga-DOTATATE/DOTATOC PET/CT (SR PET/CT) in patients with suspicion of or histopathologically proven pancreatogenic hyperinsulinaemic hypoglycaemia. METHODS: We included 13 patients with histopathologically proven or a high clinical suspicion of pancreatogenic hyperinsulinaemia. All the patients underwent a SR PET/CT scan. The results were correlated with histopathological findings. Normalization of blood glucose levels after resection of the pancreatic lesion, as well as a cytological and/or pathological diagnosis of insulinoma, was considered the diagnostic gold standard for insulinoma. The diagnosis of nesidioblastosis was based on exclusion of an insulinoma and conclusive pathological examination of a segment of the pancreas. Malignant insulinoma was defined as the presence of locoregional or distant metastases. RESULTS: Based on histopathology, 13 patients were found to have pancreatic hyperinsulinaemia: two patients had malignant insulinoma, eight had nonmetastasized insulinoma, and three had nesidioblastosis. SR PET was positive in 11 of the 13 patients (84.6 %) with a final diagnosis of endogenous pancreatic hypoglycaemia. Histopathological staining confirmed 16 foci of hyperinsulinism (insulin positivity). SR PET detected 14 of the 16 lesions, resulting in a sensitivity of 87 %. One intrapancreatic spleen was falsely diagnosed as insulinoma focus on SR PET, resulting in positive predictive value of 93.3 %. Immunohistochemical staining of somatostatin receptor (SSR) subtype 2a was available in ten specimens: two nesidioblastosis, and seven benign and one malignant insulinoma. Eight out of the ten specimens (80 %) stained strongly to moderately positive. Seven of the eight SSR2a-positive lesions were picked up on SR PET. Based on the results of SR PET/CT, nine patients achieved complete remission of the hypoglycaemic events during follow-up. CONCLUSION: This explorative study suggests that SR PET in combination with CT may play a significant role in the detection and management of patients with pancreatogenic hyperinsulinaemic hypoglycaemia. A large proportion of insulinomas express SSR2a, and a larger study is needed to fully assess the diagnostic accuracy of SR PET in patients with insulinoma and nesidioblastosis compared with current localizing studies used in clinical practice.

Contribution of ¹¹¹In-pentetreotide SPECT/CT imaging to conventional somatostatin receptor scintigraphy in the detection of neuroendocrine tumours.

AIM: The aim of the study was to assess the contribution of 111In-pentetreotide single-photon emission computed tomography/computed tomography (SPECT/CT) imaging to conventional somatostatin receptor scintigraphy (SRS) in terms of lesion characterization and localization in the detection of neuroendocrine tumours (NETs). MATERIALS AND METHODS: A total of 107 patients with suspected or confirmed NET underwent SRS and SPECT/CT after the injection of 148-222 MBq of 111In-pentetreotide. SRS and SPECT/CT images were interpreted independently. Each site of abnormal tracer uptake was recorded according to the anatomical localization, and as being consistent or not with NET. The findings were confirmed with pathological and/or clinical/imaging follow-up data. RESULTS: A final diagnosis of NET was achieved in 49/107 patients (45.8%). No evidence of NET was found in the rest. SPECT/CT resulted in a significant reduction of indeterminate cases [14/107 (13.1%) vs. 1/107 (0.9%); P<0.001] and correctly reclassified one patient as negative for NET and another as positive for NET. SPECT/CT had 87.8% sensitivity and 96.6% specificity on a patient-based analysis, statistically higher than SRS (P<0.001). A total of 160 foci were detected (108 NETs and 52 physiological/benign tumours). SRS correctly classified 105/160 foci (65.6%) and remained inaccurate for 55 lesions. These 55 included 31 indeterminate lesions, 12 lesions detected only by SPECT/CT and 12 false-positive lesions. The number of foci correctly classified on the SPECT/CT images was 151/160 (94.4%), whereas two remained indeterminate and seven were false-positive findings. CONCLUSION: SPECT/CT provides incremental diagnostic value over SRS, mainly because of a precise anatomical localization that helps discriminate between tumour lesions and physiological uptake. SPECT/CT may detect unsuspected lesions in a small proportion of patients.

Extensive extra-osseous accumulation of 99mTc-hydroximethylene diphosphonate in a patient with unsuspected dermatomyositis: Whole-body scintigraphy and SPECT/CT / Extensa captación extra-ósea de 99mTc-hidroximetilen difosfonato en un paciente con dermatomiositis no sospechada: rastreo de cuerpo completo y SPECT/TC

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Unsuspected urinoma of an obstructed kidney detected in a bone scan in a patient with lung cancer.

A 60-year-old woman with an adenocarcinoma of the lung was referred to our department for a bone scan to assess the extension of the metastatic bone disease. The images showed several foci of radiotracer uptake in the bone consistent with malignant involvement. Besides, a considerable accumulation of tracer was shown in the right perinephric region as well as in the renal pelvis. SPECT/CT images demonstrated a superior perirenal urine leak due to rupture of the collecting system. The leakage was treated by urinary catheter decompression with complete recovery after 4 weeks.

The value of early SPECT/CT and hand-held γ-camera in radio-guided surgery: a case of a hard-to-locate parathyroid adenoma.

A patient with primary hyperparathyroidism underwent radio-guided surgery by means of a γ-probe and a hand-held γ-camera. Before surgery, a parathyroid double-phase planar scintigraphy and an early SPECT/CT with 99mTc-MIBI were performed and suggested an ectopic parathyroid adenoma with early washout. The hand-held γ-camera was very useful for the localization of a parathyroid adenoma, which could not be found with the probe probably due to its faint uptake and to a high blood pool activity because it was localized next to the great vessels. Besides, it demonstrated the complete extirpation of the parathyroid tissue.

Successful treatment of metastasized pancreatic vasoactive intestinal polypeptide-secreting tumor unresponsive to high-dose octreotide by peptide receptor radionuclide therapy using 90Y DOTATATE.

We report a successful treatment of a patient with heavily metastasized pancreatic vasoactive intestinal polypeptide-secreting tumor, which was unresponsive to high doses of octreotide analog using peptide receptor radionuclide therapy applying a radiolabeled somatostatin analog. After the peptide receptor radionuclide therapy, there was a decrease in vasoactive intestinal polypeptide levels, a significant reduction in somatostatin receptor expression and in molecular tumor volume on 68Ga DOTANOC PET/CT scan, and a complete long-term resolution of symptoms of the patient.

111In-pentetreotide uptake in an ovarian teratoma and impact of SPECT/CT imaging.

We present a 19-year-old woman with a neuroendocrine tumor of the appendix diagnosed during an acute appendicitis. An 111In-pentetreotide scan was performed to establish the extension of the disease. Scintigraphy showed an abnormal focal uptake in the right side of the pelvis. The SPECT/CT images demonstrated a round-shaped mass in the right ovary. Pathology revealed a benign cystic mature teratoma. In our case, hybrid imaging combining SPECT and CT contributed to localize the unusual 111In-pentetreotide accumulation within the anatomical context.

Comparison of sequential planar 177Lu-DOTA-TATE dosimetry scans with 68Ga-DOTA-TATE PET/CT images in patients with metastasized neuroendocrine tumours undergoing peptide receptor radionuclide therapy.

PURPOSE: The aim of the study was to compare sequential (177)Lu-DOTA-TATE planar scans ((177)Lu-DOTA-TATE) in patients with metastasized neuroendocrine tumours (NET) acquired during peptide receptor radionuclide therapy (PRRT) for dosimetry purposes with the pre-therapeutic (68)Ga-DOTA-TATE positron emission tomography (PET)/CT ((68)Ga-DOTA-TATE) maximum intensity projection (MIP) images obtained in the same patients concerning the sensitivity of the different methods. METHODS: A total of 44 patients (59 ± 11 years old) with biopsy-proven NET underwent (68)Ga-DOTA-TATE and (177)Lu-DOTA-TATE imaging within 7.9 ± 7.5 days between the two examinations. (177)Lu-DOTA-TATE planar images were acquired at 0.5, 2, 24, 48 and 72 h post-injection; lesions were given a score from 0 to 4 depending on the uptake of the radiopharmaceutical (0 being lowest and 4 highest). The number of tumour lesions which were identified on (177)Lu-DOTA-TATE scans (in relation to the acquisition time after injection of the therapeutic dose as well as with regard to the body region) was compared to those detected on (68)Ga-DOTA-TATE studies obtained before PRRT. RESULTS: A total of 318 lesions were detected; 280 (88%) lesions were concordant. Among the discordant lesions, 29 were (68)Ga-DOTA-TATE positive and (177)Lu-DOTA-TATE negative, whereas 9 were (68)Ga-DOTA-TATE negative and (177)Lu-DOTA-TATE positive. The sensitivity, positive predictive value and accuracy for (177)Lu-DOTA-TATE as compared to (68)Ga-DOTA-TATE were 91, 97 and 88%, respectively. Significantly more lesions were seen on the delayed (72 h) (177)Lu-DOTA-TATE images (91%) as compared to the immediate (30 min) images (68%). The highest concordance was observed for bone metastases (97%) and the lowest for head/neck lesions (75%). Concordant lesions (n = 77; mean size 3.8 cm) were significantly larger than discordant lesions (n = 38; mean size 1.6 cm) (p < 0.05). No such significance was found for differences in maximum standardized uptake value (SUV(max)). However, concordant liver lesions with a score from 1 to 3 in the 72-h (177)Lu-DOTA-TATE scan had a lower SUV(max) (n = 23; mean 10.9) than those metastases with a score of 4 (n = 97; mean SUV(max) 18) (p < 0.05). CONCLUSION: Although (177)Lu-DOTA-TATE planar dosimetry scans exhibited a very good sensitivity for the detection of metastases, they failed to pick up 9% of lesions seen on the (68)Ga-DOTA-TATE PET/CT. Three-dimensional dosimetry using single photon emission computed tomography/CT could be applied to investigate this issue further. Delayed (72 h) images are most suitable for drawing regions of interest for dosimetric calculations.

Temporal hypoperfusion assessed by cerebral blood flow SPECT and long-term clinical outcome in patients with eating disorders.

OBJECTIVE: To evaluate the relationship between temporal hypoperfusion in the acute phase of patients with eating disorders and the long-term clinical outcome. METHOD: Brain perfusion was studied using Tc-99m HMPAO SPECT in 17 patients with eating disorders (ED) and compared with 12 controls (C). Semiquantitative analysis was carried out by left/right indexes. Clinical records were reviewed 15 years later and the patients were classified into 2 groups: bad outcome in 10 patients and good outcome in 4. The results of the basal SPECT were compared with the clinical outcome. RESULTS: The mean of the differences of temporal perfusion in the lower slice was 0.1476 +/- 0.1121 in ED and 0.03 +/- 0.019 in C (P < 0.001). Comparisons between C and bad outcome showed a significant difference (P < 0.01). There was no significant difference between good outcome and C. CONCLUSIONS: The temporal hypoperfusion in the acute phase of patients with ED showed a correlation with the long-term clinical outcome and suggested a prognostic value of temporal hypoperfusion.

Diagnosis of common iliac artery thrombosis and renal artery thrombosis in a kidney transplant by radionuclide renography.

In a 58-year-old woman, the external iliac artery was accidentally dissected during the arterial anastomosis of a kidney transplant. An immediate CT angiogram showed an almost total occlusion of the common iliac artery. After the transplantation, radionuclide renography with Tc-99m MAG3 showed no flow across the right common iliac artery and no graft vascularization. Sequential images showed a photopenic area corresponding to the renal graft. These findings were interpreted as common iliac artery thrombosis and renal artery thrombosis associated with renal graft infarct. Excision of the transplant and iliofemoral bypass were performed. Pathologic examination of the graft showed massive acute renal infarct and renal artery thrombosis.

In-111 ibritumomab scintigraphy (planar and SPECT) and FDG PET/CT before Y-90 ibritumomab treatment in a patient with mantle cell lymphoma.

We report the case of a 75-year-old man, in whom Y-90 ibritumomab was requested because of relapse of blastoid variant mantle cell lymphoma diagnosed in 1995. Before Y-90 ibritumomab treatment, FDG PET and In-111 ibritumomab scintigraphy with planar views at 24 hours, 48 hours, and 5 days, including SPECT, were performed. Discordant information between both examinations was observed as, in addition to the lesions detected by In-111 ibritumomab imaging, FDG PET detected lesions that did not take up the ibritumomab. The discrepancy shown by both radiotracers has to be kept in mind before planning treatment with Y-90 ibritumomab, and for the correct evaluation of treatment response.