Is there a future role for immunoscintigraphy in the diagnosis of colorectal carcinoma?

Immunoscintigraphy combines the advances in immunology and nuclear medicine to target tumor sites. Visualization of colorectal carcinomas is based on different monoclonal antibodies and their fragments against tumor-associated antigens labeled with gamma emitting radionuclides which accumulate in the tumor tissue due to their interaction with corresponding antigens. Available data on the role of immunoscintigraphy in detection of recurrence and metastases of colorectal carcinomas are reviewed. Despite a variety of investigations related to the application of immunoscintigraphy in diagnostics of colorectal cancer, using different radiolabeled immunoreactive agents and imaging methods there has not been a consensus among the investigators regarding the best modality of the method, including the specific radiopharmaceutical for this purpose. Some general conclusions concerning potentials of immunoscintigraphy in such diagnostics, including expectancy of the newly developed SPECT/CT systems, are suggested. The possibilities of PET imaging of colorectal carcinomas using monoclonal antibodies labeled with positron emitting radionuclides, as well as of the radioimmunoguided surgery and radioimmunotherapy are also discussed. Key words: Immunoscintigraphy, colorectal cancer, recurrences, metastases, radioimmunoguided surgery, SPECT/CT.

Estimation of the relative liver perfusion using two methods of radionuclide angiography in the patients with hemodynamic disorders in the portal system.

The aim of this study is the assessment of the relative arterial and venous contribution to the total liver blood flow (hepatic perfusion index-HPI), with two methods (S1 and S2), and estimation of their value. With this correction, HPI nonsignificantly increases (p>0.05) in all the groups of patients, with a very high correlation between the HPI (S1) and HPI (S2) values (p<0.01). In comparison to the portal perfusion in controls, values were significantly (p<0.01) lower in chronic active hepatitis and liver cirrhosis and differed between themselves (p<0.01). In the groups of cirrhotic patients with esophageal varices, sclerosated esophageal varices, recanalized umbilical vein, portal thrombosis and cavernous portal vein, portal perfusion was lower (p<0.01) than in controls, chronic active hepatitis and liver cirrhosis without collaterals. Both angioscintigraphic methods are useful for the estimation of the disturbances in the portal system. Because of the more exact estimation of the liver perfusion, S2 is recommended.

A new radionuclide approach for the quantification of left ventricular volumes: the 'geometric count based' method.

A new radionuclide method, called the 'geometric count based' (GCB) method, has been developed for the quantification of absolute left ventricular volume. As the method is based on planar radionuclide ventriculography, it is non-invasive and simple, and avoids the relatively cumbersome and longer lasting, dynamic procedure using single photon computed emission tomography, which can be used for achieving the same goal. The purpose of this study was to describe the exactness of the theoretical approach to the method and validate its accuracy both by physical experiments and the initial clinical trial, as compared to contrast ventriculography. Count based data were combined with the geometric based data assuming an ellipsoid left ventricular shape with identical short axes. The following equation for computing left ventricular end diastolic volume, EDV (in ml) was developed: EDV=2cMCtot/Cmax, where c is the manually drawn short axis (one row pixel ROI) of the prolate ellipsoid in LAO 45 degrees (cm), M is the calibrated pixel size (in cm2), Ctot is the total counts in LV ROI, and Cmax is the maximum pixel counts in the LV ROI. Physical experiments with two different 'heart shaped' phantoms were used to compare the results obtained by the GCB method with the true phantom volumes and with the method assuming LV ball shape (BLV), developed by other authors. The true volumes of cylindrical and ellipsoid phantoms of 112.5 ml and 190.5 ml were computed to be 114 ml and 196 ml by the GCB and 168 ml and 180 ml by the BLV methods, respectively. In a clinical study, GCB volumes were compared to volumes measured by using single plane contrast ventriculography in 38 coronary patients. A good correlation between the GCB method and contrast ventriculography was obtained both for EDV and end systolic ventricular volumes (r=0.94, r=0.90). Both phantom and initial clinical studies indicate that the GCB method is an accurate, non-invasive and simple radionuclide method for measuring left ventricular volumes. Additionally, it could be used even in the smallest nuclear medicine units, for example in intensive care units where there are mobile cameras.