Gamma camera

Upon administration, the anti-tumour 99mTc conjugate will congregate at the tumour site. The tumour can then be visualized using suitable y-ray detection equipment, such as a planar gamma camera. 

Various antibody preparations have been developed that facilitate imaging of vascular-related conditions, including myocardial infarction, deep vein thrombosis and atherosclerosis. Anti-myosin monoclonal antibody fragments (Fab) labelled with mIn, for example, have been used for imaging purposes in conjunction with a planar gamma camera. The antibody displays specificity for intracellular cardiac myosin, which is exposed only upon death of heart muscle tissue induced by a myocardial infarction (heart attack). 

The resolution and sensitivity of an imaging device depend on a number of variables, for example, spatial resolution in SPECT is limited primarily by collimator resolution. Typical gamma camera SPECT systems have in-plane spatial resolution in the final reconstructed image of about 12 mm for high-resolution imaging. Resolution and sensitivity in PET is given in Table 58-3. 

Figure 4. Gamma camera image of a patient with medullary thyroid carcinoma showing selective uptake of Re-186-DMSA in a tumor at the base of the neck (taken 24 h after injection).

Figure 5. Gamma camera image of a prostate cancer patient with widespread bone metastases, showing uptake of Re-188-DMSA in bone metas-tases. Left to right anterior, 3 h posterior, 3 h anterior, 24 h posterior, 24 h. 

Figure 4 A set of gamma camera images of a rabbit intravenously injected with Tc-99m-LEH. Twenty-five percent of blood was exchanged with liposome-encapsulated hemoglobin (LEH) (hypovolemic) and the animal was imaged using a gamma camera at various times after infusion. The images clearly show a prolonged circulation of LEH as evidenced by the continued grayscale intensity in heart.

New techniques have been developed for the direct measurement of mucociliary transport rates in the trachea. Yeates et al. used an external gamma camera to follow a bolus of labeled microspheres deposited in the large airways by aerosol inhalation they fitted a log-normal distri-... 

Figure 5.8. Renal specificity of a radiolabelled LMWP. Gamma-camera imaging after an intravenous injection of a radiolabelled low molecular weight protein (LMWP) in the rat, showing the predominant uptake of the LMWP by the kidneys.

Sangwan, S., IM. Agosti, L.A. Bauer, B.A. Otulana, R.I Morishige, D.C. Cipolla, ID. Blanchard, and G.C. Smaldone, Aerosolized protein delivery in asthma gamma camera analysis of regional deposition and perfusion. J Aerosol Med, 2001. 14(2) 185-95. 

Cardiac function may be evaluated by the determination of left (or right) ventricular ejection fraction (VEF). In this procedure, regions of interest are defined at the end diastolic and end systolic phases of heart beat. The ejection fraction is defined as the ratio of tracer (blood) in the heart in the contracted (systolic) versus the relaxed (diastolic) phases of the heart cycle with appropriate corrections for decay and gamma camera dead time. The value obtained provides a measure of the ability of the heart to pump blood through the lungs (RVEF) or the body (LVEF). A criticism of Ir-191m for this application has been that the half-life (4.96s) is too short to allow effective visualization and quantitation of left ventricular function in adults, particularly those with delayed transit times. A recent... 

The Rb-81/Kr-81m generator can be used as an example. Experience has shown that a large field of view (LFOV) gamma camera equipped with a high resolution collimator requires the cumulative activities for the three typical procedures summarized in Table II. Solving equation (15) by succesive... 

The gamma camera, with computer-assisted data analysis, is used together with l3lI-hippuran to measure renal function. The renogram is of most clinical value in the assessment of ureter impairment m pre-and postoperative patients with carcinoma of the cervix and other pelvic and gynecological tumors. 

Radionuclide Imaging Procedures. Brain tumors can be detected by external counting of radionuclides, a procedure introduced into general clinical use in the late 1950s. A significant advance in brain tumor imaging was the introduction of the gamma camera, which permitted more rapid studies with multiple views, as well as dynamic cerebral blood flow assessment. 

Figure 7. Gamma-camera views of a human subject with anaplastic thyroid cancer taken 24 h after intravenous injection of 25 nanomoles (2 mCi) of luln-BLEDTA. Arrows indicate metastases to the soft tissue of the face and lungs (18).

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