Background: In this study, we have investigated the feasibility of a 180 degrees DaTSCAN brain SPECT acquisition. This technique has the advantage of being 'open view' for the patient and therefore more acceptable for claustrophobic patients. It also enables easier access for a technologist to hold the patient's head during acquisition to reduce movement in confused patients or in those with severe tremor.
Methods: In the first part of this study, we validated the practicality and image quality of a 180 degrees acquisition using a DaTSCAN Alderson head phantom with different camera configurations on GE Infinia and Philips AXIS gamma cameras. The effect on image quality of using half the acquisition time was also assessed. In the second part of the study, 50 sets of patient data were reprocessed by reconstructing half of the 360 degrees data to mimic a single-head 180 degrees acquisition. The 180 degrees images were then compared with 360 degrees images for the same patient using a visual score system. The effect of half-time 180 degrees data acquisition on quantification was also assessed using GE QuantiSPECT software.
Results: All phantom images from 180 degrees acquisitions contained some degree of distortion at the periphery, but clearly retain the presence of centrally positioned caudate and putamen; hence 180 degrees acquisitions were deemed to produce clinically useful diagnostic images. The shorter (half) acquisition time leads to noisier but acceptable images for all configurations. In the patient study, there was complete agreement between the two reporters with no clinical difference in the diagnostic accuracy between the 180 degrees and 360 degrees images. However, 6 of 50 180 degrees images were marked as poor quality but reportable, compared with 0 of 50 in 360 degrees images. Quantification gave consistently lower nuclei to background ratio values for 180 degrees compared with 360 degrees for normal and abnormal patients.
Conclusion: It is possible to obtain diagnostic DaTSCAN images using 180 degrees acquisition in difficult patients. The total length of the study may also be shortened by half using L-mode or V-mode camera head configuration.