Importancia de la gammagrafía de perfusión pulmonar en el trasplante de pulmón único / Importance of the lung perfusion scintigraphy in single lung transplantation

La gammagrafía de perfusión pulmonar con 99mTc-MAA ofrece una valiosa información de los pacientes que van a someterse a trasplante de pulmón único. El empleo de esta técnica nos permite evaluar y cuantificar la función relativa de ambos pulmones para seleccionar el órgano a trasplantar. Una vez que se ha realizado la cirugía, la gammagrafía de perfusión pulmonar representa un método diagnóstico para evaluar la evolución del órgano trasplantado. Dos pacientes que fueron sometidos a este procedimiento quirúrgico fueron estudiados en nuestro hospital. En ambos se realizó gammagrafía de perfusión pulmonar preoperatoria para la selección del órgano a trasplantar, y meses después de la cirugía se realizó el estudio gammagráfico para la evaluación de la función de perfusión del órgano trasplantado(AU)

Lung perfusion scintigraphy (LPS) with 99mTc-MAA gives valuable information about patients who will undergo a single lung transplantation. This technique makes it possible to evaluate and quantify the relative function of both lungs to select the organ to be transplanted. Once the surgery has been performed, the LPS represents a diagnostic method to study the status of the transplanted organ. Two patients who underwent single lung transplantation were studied in our hospital. In both cases, a pre-operative LPS was performed before surgery for selection of the organ to be transplanted and the scintigraphy study was performed a few months after transplantation to establish the perfusion function of the transplanted lung(AU)

Importance of the lung perfusion scintigraphy in single lung transplantation.

Lung perfusion scintigraphy (LPS) with (99m)Tc-MAA gives valuable information about patients who will undergo a single lung transplantation. This technique makes it possible to evaluate and quantify the relative function of both lungs to select the organ to be transplanted. Once the surgery has been performed, the LPS represents a diagnostic method to study the status of the transplanted organ. Two patients who underwent single lung transplantation were studied in our hospital. In both cases, a pre-operative LPS was performed before surgery for selection of the organ to be transplanted and the scintigraphy study was performed a few months after transplantation to establish the perfusion function of the transplanted lung.

(99m)Tc-labeled murine ior C5 monoclonal antibody in colorectal carcinoma patients: pharmacokinetics, biodistribution, absorbed radiation doses to normal organs and tissues and tumor localization.

Monoclonal Antibody (mAb) ior C5 is a murine IgG(1) that recognizes the tumor associated antigen (TAA) ior C2, a cell surface O-linked glycoprotein carbohydrate chain not present in most normal tissues and homogeneously expressed in the cytoplasm of normal colon epithelium and heterogeneously expressed in more than 83% of primary colorectal carcinomas. This study was designed to investigate the pharmacokinetics, biodistribution and the absorbed radiation doses of (99m)Tc-labeled mAb ior C5 antibody in colorectal tumor patients. Ten patients were administered 3 mg of anti-O-linked glycoprotein carbohydrate chain TAA ior C2 murine monoclonal antibody ior C5 radiolabeled with (99m)Tc activity of 1435.0 +/- 123 MBq by intravenous (i.v.) bolus infusion. Blood and urine samples were collected from 4 out of 10 patients at timed intervals from 10 min and up to 24 h after injection of the (99m)Tc-labeled mAb ior C5 for pharmacokinetic studies. Whole body images were taken in 5 out of 10 patients for quantitative normal organ biodistribution and dosimetry studies and planar anterior and posterior and SPECT images were taken in 5 out of 10 patients for tumor localization. Mean absorbed doses were estimated using the methods developed by the Medical Internal Radiation Dose (MIRD) committee. The effective dose equivalent (EDE) and effective dose (ED) were calculated as prescribed in International Commission on Radiological Protection (ICRP) publications 30 and 60. Plasma disappearance curves of (99m)Tc-labeled murine antibody ior C5 were best fit by a two-compartment model in all patients with (t(1/2alpha)) of 4.32 +/- 2.18 h and (t(1/2beta) of 32.6 +/- 3.82 h. Among the main target organs, accumulation of the radiolabeled antibody was found in liver (9.38 +/- 0.80%), heart (8.92 +/- 0.94%) and spleen (1.37 +/- 0.30%) at 5 min post-administration. These values were reduced at 24 h to (5.91 +/- 0.73%) and (0.62 +/- 0.22%), respectively, for the heart and spleen and increased to (9.78 +/- 1.99%) for liver. Estimates of radiation absorbed dose to normal organs in rad/mCi administered were: whole body, 0.0181 +/- 0.0017; heart wall, 0.0768 +/- 0.0090; kidneys, 0.0530 +/- 0.0260; liver, 0.0565 +/- 0.0109 and spleen, 0.0540 +/- 0.0128. The effective dose equivalent and effective dose estimates for adults were 0.0314 +/- 0.0031 and 0.0249 +/- 0.0027 rem/mCi administered. This feasibility study indicates that the O-linked glycoprotein carbohydrate chain TAA ior C2 is expressed in primary and metastatic colorectal carcinomas and shows very limited expression in normal adult tissues. The very good pattern of biodistribution of (99m)Tc-labeled mAb ior C5 in patients will allow imaging of colorectal carcinoma lesions.

A way to reduce the radius of rotation in brain SPET with a single-head system.

To optimize spatial resolution in single photon emission tomography (SPET), it is essential to minimize the radius of rotation. In brain studies, different methods have been used to avoid shoulder interference when the radius of rotation is minimized: rectangular fields of view, modifications to the shielding around circular detectors and fan or cone beam collimators. However, few single-head systems can adopt these developments, particularly older cameras. A non-standard image acquisition method to reduce the radius of rotation in brain SPET with a single-head gamma camera is presented. The method applies a defined transformation to the original acquired images, maintaining the whole of the brain inside the field of view without shoulder interference and meeting the condition: pixel size < or = FWHM/3. With this method, it is possible to reduce the radius of rotation to 16 cm and to obtain a transaxial spatial resolution of 15.98 mm, which is 3.5 mm less than with the standard method used in our laboratory. This procedure was implemented for a Siemens Gammasonics ZLC 3700 gamma camera and has been validated in single-slice brain phantom studies. The method has the advantage of not requiring any complex or costly hardware.

A way to reduce the radius of rotation in brain SPET with a single-head system

To optimize spatial resolution in single photon emission tomography (SPECT), it is essential to minimize the radius of rotation. In brain studies, different methods have been used to avoid shoulder interference when the radius of rotation is minimized: rectangular fields of view, modifications to the shielding around circular detectors and fan or cone beam collimators. However, few single-head systems can adopt these developments, particularly older cameras. A non-standard image acquisition method to reduce the radius of rotation in brain SPET with a single-head gamma camera is presented. The method applies a defined transformation to the original acquired images, maintaining the whole of the brain inside the field of view without shoulder interference and meeting the condition: pixel size <= FWHM/3. With this method, it is possible to reduce the radius of rotation to 16 cm and to obtain a transaxial spatial resolution of 15.98 mm less than with the standard method used in our laboratory. This procedure was implemented for a Siemens Gammasonics ZLC 3700 gamma camera and has been validated in single-slice brain phantom studies. The methods has the advantage of not requiring and complex or costly hardware (AU)

Technetium-99m-antiepidermal growth factor-receptor antibody in patients with tumors of epithelial origin: part II. Pharmacokinetics and clearances.

UNLABELLED: Radiolabeled antitumor antibodies hold promise for diagnostic imaging and therapy in oncology. The purpose of this study was to investigate the pharmacokinetics, clearances and possible differences of two dosage administrations of the 99mTc-labeled antiepidermal growth factor (EGF)-receptor antibody and to predict the best dose and schedule for future clinical evaluations of this radiopharmaceutical. METHODS: Nine patients (4 women, 5 men; mean age 46.4 +/- 14.0 yr) were administered 1-3 mg 99mTc-labeled anti-EGF-receptor antibody (a murine IgG2a isotype) by intravenous bolus infusion. After administration, blood samples were collected from 7 patients from an antecubital vein opposite to the injection side at intervals from 2 min to 24 hr after injection, and plasma samples were obtained for pharmacokinetic analysis. Appropriate plasma samples were examined for isotope clearance (i.e., microCi/ml at various intervals) and 99mTc complexation to plasma proteins by fast protein liquid chromatography (FPLC) analysis. Urine was collected from each patient at 3 hr intervals up to 24 hr after monoclonal antibody administration to monitor 99mTc clearance. Plasma time-activity curves were fitted to a two-compartment model using nonlinear least-squares regression analysis by the method of flexible polyhedrals. RESULTS: Plasma disappearance curves of 99mTc-labeled anti-EGF-receptor antibody were best fit by biexponential equation with a distribution half-life (t(1/2alpha)) of 0.137 +/- 0.076 hr (n = 7) and elimination half-life (t(1/2beta)) of 20.3 +/- 8.0 hr. Analysis of urine showed that activity clearance by this route amounted to 4.9% +/- 0.6% of the injected dose in 24 hr, and FPLC analysis showed no evidence of decomposition, only 6%-7% of 99mTc was in a low molecular weight species. CONCLUSION: Plasma pharmacokinetics and urine clearance indicate comparability in both doses. The pharmacokinetic properties of the 99mTc-labeled anti-EGF-receptor antibody were found to be dose-independent. These findings provide an initial characterization of the radiopharmaceutical disposition in patients and may be used as the basis for calculating a better estimate of biodistribution and dosimetry for patients who will receive 188Re-labeled anti-EGF-receptor antibody (MAb ior egf/r3) injection for radioimmunotherapy and warrants further controlled clinical trials to define the efficacy of the radiopharmaceutical.