José Luis Carreras Delgado

La tomografía por emisión de positrones (PET) y PET-TAC en riñón, vías urinarias y próstata: Actualización

PET has demonstrated its utility in management decisions in several types of tumors. In urologic tract tumors and prostate cancer its diagnostic performance has been lower due to the urinary excretion of the radiotracer, which can mask the presence of lesions. However, specific protocols must be applied that improve the diagnostic performance of PET with 18F-FDG in the evaluation of pelvic lesions. Furthermore, prostate cancer is a low-grade tumor with low avidity for 18F-FDG. In spite of these limitations, with PET new and interesting possibilities have been presented. The availability of PET-CT systems has improved its diagnostic performance. On the other hand, the development of new radiotracers that allow targeting other molecular processes and that are metabolized by pathways different to the urinary tract signifies an important advantage compared to 18F-FDG and has evidenced interesting results.

SPECT-CT in sentinel node detection in patients with melanoma

Abstract Introduction The prognosis of patients with cutaneous melanoma is greatly influenced by the presence of lymph node metastases. One of the most innovative and fascinating concepts to emerge in the field of oncology in recent years is the use of sentinel lymph node biopsy (SLNB). Aim The aim of this study was to determine what SPECT-CT images contribute to the search for sentinel nodes in patients with melanoma. Methods From March 2007 to October 2008, 18 patients were examined for sentinel nodes using dynamic scintigraphy, planar images, and SPECT-CT in the Nuclear Medicine Department of San Carlos University Hospital. The group contained 10 women and 8 men, age range 14-83 years, mean age 57 years (57±20.1). Results The sentinel node was located by conventional imaging techniques (dynamic scintigraphy and planar images) in 16 of 18 patients (88.88%). SPECT-CT identified the sentinel node in 18 of 18 patients (100%) and detected clinically relevant findings in 6 of 18 patients (33.33%) Conclusions SPECT-CT imaging contributed clinically relevant information on sentinel nodes of melanoma, which is particularly important in patients with melanoma of the trunk or head and neck.

Predictive value of PET-CT for pathological response in stages II and III breast cancer patients following neoadjuvant chemotherapy with docetaxel

PURPOSE To prospectively study the value of PET-CT with fluorine-18 fluorodeoxyglucose (FDG) to predict neoadjuvant chemotherapy (NAC) response of locoregional disease of stages II and III breast cancer patients. MATERIAL AND METHODS A written informed consent and approval were obtained from the Ethics Committee. PET-CT accuracy in the prediction of pathologic complete response (pCR) after NAC was studied in primary tumors and lymph node metastasis in 43 women (mean age: 50 years: range: 27-71 years) with histologically proven breast cancer between December 2009 and January 2011. PET-CT was performed at baseline and after NAC. SUV(max) percentage changes (ΔSUV(max)) were compared with pathology findings at surgery. Receiver-operator characteristic (ROC) analysis was used to discriminate between locoregional pCR and non-pCR. In patients not achieving pCR, it was investigated if ΔSUV(max) could accurately identify the residual cancer burden (RCB) classes: RCB-I (minimal residual disease (MRD)), RCB-II (moderate RD), and RCB-III (extensive RD). RESULTS pCR was obtained in 11 patients (25.6%). Residual disease was found in 32 patients (74.4%): 16 (37.2%) RCB-I, 15 (35.6%) RCB-II and 2 (4.7%) RCB-III. Sensitivity, specificity, and accuracy to predict pCR were 90.9%, 90.6%, and 90.7%, respectively. Specificity was 94.1% in the identification of a subset of patients who had either pCR or MRD. CONCLUSION Accuracy of ΔSUV(max) in the locoregional disease of stages II and III breast cancer patients after NAC is high for the identification of pCR cases. Its specificity is potentially sufficient to identify a subgroup of patients who could be managed with conservative surgery.

Adrenocortical Carcinoma: False Positive in an I-123 Metaiodobenzylguanedine Scan

A 55-year-old man with a personal history of left pheochromocytoma 2 years previously presented with an abdominal mass. Tumor relapse was suspected.Abdominal ultrasound showed a large left upper quadrant solid mass (calipers), with heterogeneous echogenicity and central cystic degeneration areas or necrosis (Fig. 1a). A computed tomography (CT) scan showed surgical clips of left adrenalectomy and multiple confluent left upper quadrant masses with a maximal diameter of 19 cm and heterogeneous enhancement (Fig. 1b). Both CT scan and ultrasound images were suspicious of adrenocortical carcinoma (ACC): size, heterogeneity and diaphragm invasion among other radiological features. Clinically, the mass grew in a few months and there were no paroxysmal hypertension episodes, nor elevation of catecholamines (cathecholamine urine test: 37.2 μg/g creatinine, normal range 0.1-260). F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT was performed as ACC was suspected (2). ACC is an uncommon malignant neoplasm of unknown cause; however, smoking and oral contraceptives may be risk factors [1, 2]. Patients usually present with advanced-stage disease and have poor prognosis [3], with a 2-year recurrence rate that ranges from 73 to 86 % [4]. CT or magnetic resonance (MR) is most often used for initial staging of ACC and usually shows heterogeneous adrenal mass with variable enhancement of solid components [4]. F-18 FDG PET has been used successfully for detection of adrenal metastases and for staging ACC [5]. Most ACCs accumulate and retain FDG [2, 6]. However, FDG PET cannot differentiate among malignant lesions (metastases, ACC, malignant pheochromocytoma, and lymphoma). Also, most pheochromocytomas (benign or malignant) are metabolically active and might accumulate FDG [7, 8]. A whole-body FDG PET scan (coronal and axial view) shows increased irregular FDG uptake in the abdominal masses (Fig. 2). An I-123 metaiodobenzylguanedine (MIBG) scan was requested to rule out pheochromocytoma because, although conventional image methods (ultrasound and CT) and also PET/CT scan were suspicious of ACC, the primary histology of the tumor was consistent with pheochromocytoma. An MIBG scan was performed after injection of 185 MBq of I123 MIBG intravenously. Single photon emission tomography (SPECT)/CT scan showed abnormal isotope accumulation in the tumor region. The patient underwent total resection of the tumor. The histology was of ACC, with areas of necrosis and cystic areas, so the result of the MIBG scan was a false positive. No positive chromaffin staining or chromogranin ISSN (print) 1869-3474 ISSN (online) 1869-3482

Head and Neck Cancer

Head and neck neoplasms are an important and frequent condition, where squamous cell carcinomas are the most common subtype, accounting for 5 % of all cancers. CT or MRI is mandatory performed in pretherapeutic staging and monitoring treatment in patients with head and neck cancers. Morphologic imaging techniques are often insufficient for themselves to discriminate small recurrences from vascularized scar tissue. In those cases, CT or MRI requires to be integrated with functional imaging techniques (perfusion CT, dynamic contrast-enhanced MRI, MRS, and DWI). PET/CT offers valuable opportunities for the assessment of head and neck cancer in all phases of the disease. It emerges, beyond doubt, as a useful and cost-effective tool in pretreatment staging and in recurrent disease detection. FDG imaging shows great promise in treatment planning and assessment of treatment response. Alternative tracers are yielding information on tumor biology and new imaging techniques associated to MRI which could be crucial in the clinical management of head and neck cancer patients.