M. Roca

Characterization of radiologically indeterminate lung lesions: 99mTc-depreotide SPECT versus 18F-FDG PET.

AimTo evaluate the diagnostic accuracy of 99m Tc-depreotide vs PET-18FDG scans in patients with suspicion of lung cancer Material and methodsProspective study in 29 patients (age: 38-80 years) diagnosed of inderteminate lung lesions. Diagnosis was established by histology based on samples of surgical resection, fine needle aspiration (FNA) or broncoalveolar lavage (BAL). Within a maximum of 10 days, without pre-established fixed order the following exams were performed: 1) Whole body and chest SPECT-CT with 99mTc-depreótide (DEP-SPECT) and 2) PET-CT study with 18F-FDG (PET-FDG). Every exam was evaluated by Nuclear Medicine especialist blinded to patient data. ResultMalignancy was confirmed in 20 patients. PET-FDG was positive in all cases. DEP-SPECT was positive in 17 and falselly negative in 3, one carcinoid tumor, one undifferentiated non-small cell adenocarcinoma, and a moderately differentiated adenocarcinoma. In the remaining 9 patients benignancy was confirmed; both studies were normal in 8 and falselly positive in one case of non-specific inflammatory lung process.In 9 out of the 20 cases with malignancy extrapulmonar uptake was seen, with a total number of 19 lesions. In two cases the extrapulmonar uptake were non ganglionar metastasis (bone and adrenal) and in 7 due to mediastinic ganglionar involvement. ROC analysis using peak SUV FDG (cut-off point of 3.5) uptake and target/background depreotide uptake (cut-off point of 1.3) provided, sensitivity and specificity values of 95% and 89% of 84% and 88% for PET and SPECT respectively. It does not exist statistically significant differences between both methods (Z-test SPSS).In summary, FDG-PET has a greater sensitivity and diagnostic accuracy for assessing malignancy of indeterminate lung lesions, and for detection of extrapulmonary involvement, DEP-SPECT represents a good diagnostic alternative for centers where PET is not available.

Simultaneous administration of 99Tcm-HMPAO-labelled autologous leukocytes and 111In-labelled non-specific polyclonal human immunoglobulin G in bone and joint infections

The aim of this study was to investigate the ability of 111In-labelled human polyclonal immunoglobulin G (111In-IgG) to localize bone and joint infections compared with 99Tcm-HMAPO-labelled leukocytes (99Tcm-WBC). Thirty-four patients routinely referred for investigation of bone and joint infections were studied. In all patients, a bone scan using 99Tcm-MDP was initially obtained. Subsequently, 99Tcm-WBC and 111In-IgG were simultaneously injected and images obtained at 30 min, 4 h and 24 h post-injection. Diagnostic accuracy was established by bacteriology of specimens obtained by needle aspiration and/or surgery, other imaging methods and clinical follow-up. The images were read by three experienced observers blinded to any other information; the clinical suspicion of infection and the diagnosis were established when two observers agreed. Infection was confirmed in 11 patients. The 99Tcm-WBC scans gave 8 true-positive, 5 false-positive, 18 true-negative and 3 false-negative results. With 111In-IgG, the figures were 7, 6, 17 and 4, respectively. The sensitivity, specificity and accuracy were 72.7%, 78.2% and 76.4% respectively for the labelled leukocytes and 63.6%, 73.9% and 70.6% respectively for 111In-IgG. There was greater agreement between the observers with 99Tcm-WBC than 111In-IgG. In this study, 111In-IgG was less sensitive and less specific than 99Tcm-WBC scintigraphy for the diagnosis of chronic infections, but these differences were not significant. Both tracers appear to be useful in the diagnosis of bone and joint infections. However, our results were less reliable for the diagnosis of an infected prosthesis.

Influencia de la localización del cáncer de mama en la detección del ganglio centinela

Resumen Objetivo Valorar la influencia del cuadrante de localizacion del cancer de mama en la deteccion del ganglio centinela (GC) y en la visualizacion del drenaje a mamaria interna mediante tecnicas radioisotopicas. Se estudiaron 376 pacientes con cancer de mama; edad media: 57 anos (rango 29-88). A todas se les inyecto peritumoralmente 37-74 MBq de 99m Tc-nanocoloide, en 2 ml. El tumor se localizo en cuadrante superoexterno (CSE) en 189 pacientes, en inferoexterno (CIE) en 57, en superointerno en 57 (CSI), en 55 en inferointerno (CII) y en 18 en el central. Se obtuvieron imagenes gammagraficas en proyecciones anterior y lateral a las 2 horas postinyeccion del trazador. Se realizo marcaje cutaneo del GC para facilitar su localizacion quirurgica. Se utilizo una sonda gammadetectora para la deteccion intraquirurgica. Se realizo impronta del GC extirpado. El estudio histopatologico diferido se realizo mediante tecnicas de hematoxilina-eosina, inmunohistoquimia (CAM 19-2) y PCR. Resultados La deteccion gammagrafica y quirurgica del GC fue respectivamente 90% y 93% en CSE, 91% y 95 % en CIE, 93% y 95 % en CSI, 87% y 95 % en CII y 94% y 83 % en el central. El drenaje linfatico a mamaria interna fue de 6% en CSE, 5% en CIE, 12 % en CSI, 20 % en CII y ningun caso en el central. Conclusiones Estos resultados sugieren que la deteccion tanto gammagrafica como quirurgica del GC es independiente del cuadrante de localizacion del cancer. Los tumors localizados en los cuadrantes internos muestran un mayor porcentaje de drenaje linfatico a la cadena mamaria interna.

Renogram deconvolution in the management of diabetic nephropathy: utility of the measurement of initial tracer uptake.

Our objective was to assess mean transit time (MTT) and initial uptake, both parameters derived from the renal retention function (RRF), in the study of renal function in patients with diabetic nephropathy. We studied 25 patients, 7 with type I diabetes mellitus and 18 with type II diabetes mellitus, all of whom fulfilled the criteria for diabetic nephropathy with proteinuria and/or retinopathy. We found a statistically significant correlation between initial uptake and the other biochemical and renographic parameters studied except proteinuria: serum creatinine (r = 0.66, P < 0.002), creatinine clearance (r = 0.61, P < 0.003), glomerular filtration rate (r = 0.74, P < 0.003) and effective renal plasma flow (r = 0.66, P < 0.003). The other renographic parameters studied (maximal activity of the conventional renogram and MTT of the deconvoluted renogram) did not show any correlation. Initial uptake is a semi-quantitative renographic parameter that can provide complementary information to biochemical data and it may be useful in the management of diabetic nephropathy, especially in patients with high serum creatinine or creatinine clearance.

Estudio de la evolución del trasplante renal mediante la deconvolución del renograma con 99mTc-mercapto-acetil-triglicina (Mag-3)

Resumen Objetivo Evaluar la utilidad de los parametros obtenidos a partir de la deconvolucion del renograma con 99mTc-MAG3 en la monitorizacion de la funcion de los injertos renales. Material y metodo Se ha estudiado 221 renogramas con el siguiente diagnostico: 64 injerto funcionante (IF), 37 injerto funcionante con creatinina elevada (IF2); 59 necrosis tubular aguda (NTA), 30 rechazo agudo (RA); 20 obstruccion de vias urinarias (OBS) y 11 nefrotoxicidad (NTX). Los parametros estudiados han sido: 1) del renograma: la actividad maxima y 2) de la funcion de retencion renal (FRR): tiempo de transito medio (TTM), tiempo de caida del 20 % (T20) y del 80% (T80) de la FRR y captacion inicial (CI). Resultados El TTM y el T20 han sido significativamente mas largos y la CI significativamente menor en los injertos no funcionantes. Sin embargo, el TTM y el T20 se acortan mas que en el IF cuando la funcion esta severamente afectada. Conclusiones La CI, TTM y T20 son mas utiles que la actividad maxima del renograma en la monitorizacion del injerto renal y en la valoracion de la severidad de la afectacion funcional del mismo. La CI parece ser el parametro mas precoz y sensible.

Validation of the preparation of individual doses of 131I-sodium o-iodohippurate (131I-hippuran)

The preparation of low activity doses of 131I-hippuran has a drawback due to its high radioactivity concentration. In this study we diluted the radiopharmaceutical with saline or phosphate buffered saline (PBS) in order to decrease the radioactivity concentration, facilitate the preparation of individual doses and validate these procedures. We prepared doses of approx. 1.85 MBq of 131I-hippuran from 10 different batches the day before the calibration date: undiluted, and diluted 1:9 with saline or PBS. The radiochemical purity (RCP) was evaluated the day after the expiry date. The percentage of 131I-hippuran retained on syringes was assessed in vitro, after emptying the syringe and washing it twice with water (n = 3×27); and in vivo, after the endovenous administration of the dose and washing the syringe twice with the patients blood (n = 3×75). Sterility was assessed using fluid thyoglicolate medium (n = 3×15). All RCP values were greater than those required by the European Pharmacopoeia (>96%) except one of the undiluted 131I-hippuran (95.8%) doses. No statistical difference was observed among them. The mean undiluted 131I-hippuran retained in vitro was 5.4% (SD = 6.5%), statistically greater (P<0.01) than both saline diluted (mean = 1.5%, SD = 1.1%) and PBS diluted (mean = 2.0%, SD = 2.4%). The mean undiluted 131I-hippuran retained in vivo was 6.4% (SD = 5.4%), statistically greater (P<10−5) than both saline diluted (mean = 3.1%, SD = 2.3%) and PBS diluted (mean = 3.1%, SD = 3.1%). We concluded that: (1) the dilution of 131I-hippuran with saline or PBS makes both the preparation of individual doses and its administration to the patient easier without decreasing its radiopharmaceutical quality; and (2) using saline or PBS diluted 131I-hippuran the percentage of radiopharmaceutical retained on the syringes, after use, is minimized.

Measurement of the Abdominal Retention of 75Se-Homotaurocholic Acid (SeHCAT) in Patients with Diarrhoeic Syndromes

We investigated the clinical usefulness of SeHCAT test in management of 28 patients with diarrhoeic syndrome using a collimated gammacamera. Abdominal retention of 75 Se (AR) lower than 8% suggests ileal disfunction that decreases the absorption of bile acids, as the cause of the diarrhoea. In patients with diarrhoeic syndromes this decrease can be used as criterion to establish specific treatment. In patients with normal AR other causes of diarrhoea must be looked for.