Preliminary evaluation of cerebral 18F-DOPA PET/CT in the differential diagnosis of brain lesions in inconclusive MR.

AIM: To evaluate the utility of brain 18F-DOPA PET/CT in the differential diagnosis of brain lesions with inconclusive MRI. MATERIAL AND METHODS: Twelve patients were studied, with a total of 16 lesions, without definitive diagnosis after brain MRI. A double acquisition PET/CT brain scan was acquired at 20 and 90min. Visual and semiquantitative assessment was performed with SUVmax calculation of the lesions and calculation of the T/S Ratio (tumor/contralateral striatum) and T/N Ratio (contralateral healthy tumor/parenchyma) for each time. RESULTS: Based on the visual assessment scale and using T/S ratio ≥1 and T/N ratio ≥1.3 to determine malignancy, the values of sensitivity (S), specificity (E) and positive predictive value (PPV) were: visual assessment (S 100%, E 33.3%, VPP 71.4%), T/S Ratio (S 90%, E 100%, VPP 100%) and T/N Ratio (S 100%, E 16.6%, VPP 66.6 %). No lesion showed an increase in SUVmax in late acquisition. 18F-DOPA PET/CT modified treatment in 75% of the patients. CONCLUSION: 18F-DOPA PET/CT is a useful tool in the study of brain lesions with inconclusive MRI. Late imaging (dual-point) has no added value in the final diagnosis. FDOPA has an impact on patient management modifying therapeutic behavior.

68Ga-PSMA-11 PET/CT in patients with occult biochemical recurrence of prostate carcinoma and negative 18F-Choline PET/CT. Preliminary assessment of its clinical use.

OBJECTIVE: To assess the clinical usefulness of 68Ga-PSMA PET/CT studies in patients with occult biochemical recurrence of prostate carcinoma, with negative or inconclusive radiologic and 18 F-Choline PET/CT imaging studies. MATERIAL AND METHODS: Retrospective descriptive study. The first 14 patients with a history of prostate carcinoma, treated with curative intent and presenting suspicion of biochemical recurrence with low PSA values (<3 ng/mL) were selected. Imaging studies, prostate ultrasound, pelvic CT and/or MRI were negative, and all of them had a negative or inconclusive 18F-Choline PET/CT. All patients were referred to 68 Ga-PSMA-11 PET/CT. PROTOCOL: Dose 2.2 M Bq/kg. 20 mg furosemide at start. PET/CT images from skull base to proximal third of thighs at 60 min, and late images at 3 h if needed. RESULTS: The 68 Ga-PSMA-11 PET/CT was able to localize the occult biochemical recurrence in 9 of the 14 patients (64.2%), and it affected the therapeutic attitude in all of them. Four patients (28.5%) obtained a negative or inconclusive 68 Ga-PSMA-11 PET/CT and continued under vigilant approach with PSA controls and imaging studies according to the clinical guidelines. These patients had the lowest PSA values (less than 1 ng/mL). One of the 68 Ga-PSMA-11 PET/CT studies was inconclusive, reporting the presence of a doubtful right iliac adenopathy. CONCLUSION: 68 Ga-PSMA-11 PET/CT allows an early diagnosis, with low PSA values, of occult biochemical recurrence of prostate carcinoma, even in patients with negative 18 F-Choline PET/CT.

Valoración preliminar de la 18F-DOPA PET/TC cerebral en el diagnóstico diferencial de lesiones cerebrales con RM no concluyente.

AIM: To evaluate the utility of brain 18F-DOPA PET/CT in the differential diagnosis of brain lesions with inconclusive MRI. MATERIAL AND METHODS: Twelve patients were studied, with a total of 16 lesions, without definitive diagnosis after brain MRI. A double acquisition PET/CT brain scan was acquired at 20 and 90 minutes. Visual and semiquantitative assessment was performed with SUVmax calculation of the lesions and calculation of the T/S ratio (tumor/contralateral striatum) and T/N ratio (tumor/contralateral healthy parenchyma) for each time. RESULTS: Based on the visual assessment scale and using T/S ratio ≥ 1 and T/N ratio ≥ 1.3 to determine malignancy, the values of sensitivity (S), specificity (E) and positive predictive value (PPV) were: visual assessment (S 100%, E 33.3%, VPP 71.4%), T/S ratio (S 90%, E 100%, VPP 100%) and T/N ratio (S 100%, E 16.6%, VPP 66.6%). No lesion showed an increase in SUVmax in late acquisition. 18F-DOPA PET/CT modified treatment in 75% of the patients. CONCLUSION: 18F-DOPA PET/CT is a useful tool in the study of brain lesions with inconclusive MRI. Late imaging (dual-point) has no added value in the final diagnosis. F-DOPA has an impact on patient management modifying therapeutic behavior.

PET/TC imaging with somatostatin analogues for assessment of neuroendocrine tumors, initial experience. / PET/TC con análogos de la somatostatina en el estudio de tumores neuroendocrinos, experiencia inicial.

PET with somatostatin analogues (SSA PET/CT) enables the detection of cells with overexpression of somatostatin receptors, especially subtypes 2 and 5; this detection is variable depending on the type of molecule used. This is the basis for its use in the study of neuroendocrine tumours (NETs), which are characterized by an overexpression of these receptors in more than 80% of the subtypes. This PET is now being used in our country supported by the good results published by other groups, that were superior to those of other imaging techniques. We present two of the first cases of SSA-PET/CT with 68Ga-edotreotide (SomaKit TOC®) performed in our centre. SSA-PET/CT was the test that finally determined the clinical management of both patients.

Perfusion SPECT, SISCOM and PET (18)F-FDG in the assessment of drug- refractory epilepsy patients candidates for epilepsy surgery.

AIMS: Brain perfusion SPECT (ictal-interictal), SPECT images and subtraction ictal SPECT coregistered to MRI (SISCOM) and (18)F-FDG-PET (interictal), play an important role in the pre-surgical diagnosis of patients with medically refractory epilepsy. This study aimed to establish: the reproducibility of visual ictal-interictal SPECT and SISCOM analysis altogether with the capacity of SPECT, SISCOM and PET to determine the epileptogenic zone. MATERIAL AND METHODS: (99m)Tc-HMPAO SPECT ictal-interictal and SISCOM (Analyze 7.0) were performed on 47 refractory epilepsy patients (24 F, 19-60 yrs). In 13 patients, SISCOM was also performed using a new program (Focus DET). Ictal-interictal SPECT and SISCOM images were analysed independently by two nuclear medicine physicians (observer 1 and 2). Kappa concordance coefficient was used to evaluate the reproducibility. In sixteen patients, SPECT, SISCOM and PET findings were compared with the resected area during the surgery, and surgical outcome using Engel scale or with the stereo EEG-(SEEG). RESULTS: The ictal-interictal SPECT interobserver agreement was 91%, Kappa index 0.86, SISCOM (Analyze 7.0) interobserver agreement percentage was 82%, Kappa index 0.80, Analyze 7.0 showed a higher inconclusive results than visual SPECT analysis. SISCOM FocusDET interobserver agreement was 92%, Kappa index 0.87, with lower inconclusive results than Analyze 7.0. SPECT, SISCOM and PET combined findings identified 87% seizure onset zone: 79% temporal, 26% parieto-temporal and 7% frontal. CONCLUSIONS: Ictal-interictal SPECT and SISCOM showed a high reproducibility in this sample of patients with drug-refractory epilepsy. SPECT,SISCOM and PET combined findings improved detection of epileptogenic zone in comparison with the individual assessment.

[Interobserver agreement in the visual and semi-quantitative analysis of the 123I-FP-CIT SPECT images in the diagnosis of Parkinsonian syndrome]. / Concordancia interobservador en el análisis visual y semicuantitativo de las imágenes SPECT (123)I-FP-CIT en el diagnóstico del síndrome parkinsoniano.

AIMS: Using (123)I-FP-CIT SPECT images makes it possible to identify presynaptic deterioration of the dopaminergic pathway by studying the dopamine transporter (DAT). A correct analysis of the SPECT images contributes to an adequate interpretation and diagnosis of movement disorders. Aims: 1. To compare visual and semiquantitative analysis of (123)I-FP-CIT SPECT images in patients with movement disorders. 2. To evaluate interobserver agreement in visual and semiquantitative analysis. 3. To obtain a cut-off in the semiquantitative analysis to discriminate primary Parkinsonism Syndrome (PS) from non-primary PS. METHODS: A (123)I-FP-CIT SPECT was performed in 32 patients with movement disorders suggestive of primary PS. Visual and semiquantitative images analyses were performed independently by two nuclear medicine physicians. Visual analysis was based on the visual interpretation. Semiquantitative analysis was calculated as specific uptake (caudate, putamen and striatum) versus non-specific uptake (occipital). Sensitivity, specificity, PPV, and NPV were calculated. Data were compared using ANOVA test followed by Bonferroni post-hoc test. Interobserver agreement of the visual and semiquantitative analysis was assessed by intraclass correlation coefficient and Kappa statistics, respectively. ROC curve was generated with semiquantitative data. RESULTS: Visual analysis showed 86% sensitivity and 100-88% specificity for the differential diagnosis of primary PS from non-primary PS. Semiquantitative analysis showed a gradual hypo-uptake proportional to the disease severity obtained in the visual analysis. Semiquantitative analysis did not provide any additional information to the visual analysis. Intraclass correlation coefficient and Kappa statistics showed 0.92 and 0.80 values, respectively. The Cut-off value to differentiate primary PS from non-primary PS was 1.9 on the putamen index.

Meal size can be decreased in obese subjects through pharmacological acceleration of gastric emptying (The OBERYTH trial).

BACKGROUND: Entry of nutrients into the small intestine activates neuro-hormonal signals that regulate food intake through induction of satiation. OBJECTIVE: To evaluate whether caloric intake can be decreased by pharmacologically accelerating gastric emptying (GE) of nutrients into the small intestine. METHODS: Subjects were tested in 2 days, at baseline (day1) and after randomly receiving, in a double-blind manner, a 1 h infusion of erythromycin (3 mg Kg(-1), to accelerate GE) or placebo (day 2). Ad libitum caloric intake and postprandial gastrointestinal symptoms were evaluated using a validated nutrient drink test, simultaneously measuring gastric emptying [corrected] by scintigraphy. Plasma levels of satiation factors were also measured to evaluate their role in the modification of caloric intake and postprandial symptoms. Acceleration of GE was assessed as the difference in percentage emptied between day 2 and day 1 (DGE). The effects of DGE on caloric intake and symptoms were evaluated using multiple (lineal) regression. RESULTS: Among 30 overweight/obese subjects (24F and 6 M), 15 received erythromycin and 15 placebo. The overall median age was 36 years (IQR: 30-42) and body mass index was 30 Kg m(-2) (IQR: 27-36). Subjects receiving erythromycin on day 2 presented accelerated GE as compared with placebo (P = 0.0002). DGE at 15 min after initiating eating had a significant effect on prospective caloric intake (P = 0.004). From the best-fitted regression model (R (2) = 81%, P < 0.0001), a 10% increase in GE at 15 min induced on an average a 135 ± 43.5 Kcal decrease in caloric intake. Postprandial increase in cholecystokinin (CCK) (P = 0.03) and insulin (P = 0.02) was associated with decreased caloric intake. Acceleration of GE at 60 min after initiating eating increased postprandial symptom scores measured 30 min after the completion of food consumption (P = 0.01). Postprandial increase in CCK (P = 0.002) and PP (P = 0.02) was associated with postprandial symptoms. CONCLUSION: Meal size can be reduced in overweight/obese subjects by pharmacologically accelerating GE. This may be a reasonable target in obesity management.

[Utility of inspiratory diagnostic CT scan after CT/PET study in the detection of pulmonary nodules]. / Utilidad de la TC diagnóstica inspiratoria tras la realización del estudio PET/TC en la detección de nódulos pulmonares.

We present the case of a 57-year old woman diagnosed of papillary thyroid carcinoma and treated with thyroidectomy followed by radioiodine (I-131) on two occasions. Follow-up radioiodine scan showed disease in right cervical region, confirmed by fine needle aspiration (FNA) and treated with lymphadenectomy. Due to thyroglobulin elevation, I-131 scan negative and inconclusive cervical ultrasonography/CT scan, we conducted a CT/PET study that confirmed cervical disease. An additional CT scan that was performed on maximum-inspiration showed four micro-nodules, one of which was not detected by the CT scan on shallow breathing (CT/PET). Post-treatment (I-131) scan confirmed uptake in these localizations. Good fusion between PET and CT images that avoids the errors of attenuation correction, especially in the lung bases, is necessary for correct image interpretation of the CT/PET study. Shallow breathing is necessary in order to obtain optimal image fusion with the CT/PET study, although this is not the best to evaluate pulmonary parenchyma in which an additional inspiratory CT scan improves detection of the pulmonary nodules.