Radionuclide/radioisotope or analog used without, or more commonly with chemical alteration by combining with physioogically “active” compound to create a radiopharmaceutical. Radiotherapy is a branch of nuclear medicine utilising particulate radiation usually beta particles (most energy deposited in couple of mm; eg I-131, phosphorous-32, strontium-89, samarium-153, yttrium-90).
Interpreting Nuclear Medicine Scans
- Determine radiopharmaceutical, type of study, age, sex, site of injection, temporal sequence of images, type of images (planar/tomographic, static/dynamic), patient orientation. Relative count density (usually Tc-99 relatively high, medium/high energy lower counts hence noisy images). Time/frame? Delay?
- Study biodistribution of activity and anatomy in the images. Normal biodistribution or focal abnormality? Areas of missing normal uptake?
- Orderly approach:
- SPECT myocardial perfusion – Evaulate raw data images for quality control issues, artifacts, ancillary/incidental findings. Check exercise data ?adequate stress and check for pharmacologic usage. Review short-axis -> vertical long-axis -> horizontal long-axis. Are perfusion abnormalities fixed or change between stress and rest? Chamber size increased with stress? Evaluate wall motion, brightening, thickening. End-diastolic and end-systolic volumes. Evaluate stress and rest data (including EF).
- V/Q – Review CXR or CT (essential prior to stating definite PE likelihood). Check for perfusion defects (size, location), confirm on more than one view then attempt to match to ventilation study.
- Flow studies/dynamic imaging/hepatobiliary – Study in order of acquisition (flow study then dynamic then statics). If liver doesn’t appear later suspect portal HTN. Early GB fossa flow implies significant inflammation. Check when GB/bowel activity first became present. Correct sequence of activity? Activity in areas other than expected? Focal accumulations?