Motion-free thoracic infant scan follow-up study after chemotherapy
Author: Susann Skoog, MD, Nils Dahlström, MD, and Petter Quick, Technologist and Application Specialist Department of Radiology and Center for Medical Image Science and Visualization (CMIV), University Hospital, Linköping, Sweden
A three-year-old boy with small (7-8 mm diameter) lung metastases from a germ cell tumor, successfully treated with chemotherapy, was referred for follow-up CT of the thorax. In a previously acquired CT examination without sedation, utilized 59.95 DLP / scan length 140 mm, the patient was not cooperative. In the present Flash scan, no remaining metastases where identified, and the serum tumor marker Alpha Fetoprotein (AFP) levels are normal.
The ultra-fast thoracic scan mode using pitch value of 3 did not reveal any metastatic lesions or other pathological findings in the thorax. Both lungs are well perfused and there is no sign of any enlarged lymph nodes. The size of the thymus has increased moderately. Inverted Maximum Intensity Projection (MIP) showed a regular bronchial tree.
Continuous follow-up CT examinations are necessary to monitor the treatment effect and determine the complete patient response. Using Somatom Definition Flash CT for a high-pitch spiral acquisition the patient is examined with greatly reduced radiation dose in comparison to standard CT protocols, in this case only 1.08 mSv where applied. The fast scan mode which acquires the patients’ thorax in only 0.42 seconds avoids the need to sedate the pediatric patient; and a motion free scan results in a valuable examination (and diagnosis) without the need of a second scan.