The analyses were applied to the whole sample (N = 390) excluding the poor quality scans and to a subsample comprising the scans with no, or minor defects (N = 344).
In addition, we chose not to exclude any poor quality scans, which may cause larger differences.
"We see a lot of poor-quality scans," said Dr. Freddie Fu, the chairman of the orthopedic surgery department at the University of Pittsburgh Medical Center.
All poor-quality scans were rejected, defined as those with signal strength of ≤6 by Cirrus.
A further 39 subjects were excluded because of poor-quality scans (on the basis of the internal quality control).
Proper power calculation of the study should include certain excess attrition rate due to poor quality of scans, patient dropout or ineligibility based on BL scan.
Clearly, the restrictions inherent to the filing and indexing system of the industry's archives are problematic when conducting a systematic review of documents; the indexing system of archives is not always consistent and full-text research tools might not recognize words due to the poor quality of scanned documents.
Scans with any artifacts or poor quality were removed, abdominal scans obtained at or above the L3/L4 level or at or below the L5/S1 level were removed, and mid-thigh scans obtained from a different leg or a slice location on the femur >2 cm of the baseline scan were removed.
The quality of structural MRI scans was rated according to a five-point rating scale by an experienced radiologist (MPW) as 1: no motion artifacts, excellent quality, 2: little motion artifacts, good quality, 3: moderate motion artifacts, acceptable quality, 4: excessive motion artifacts, poor quality, and 5: incomplete scan (Fig. 2).
After exclusion of 11 individuals without MRI scans or with poor-quality Florbetapir scans, we composed two groups from the remaining participants.
Scan quality (i.e. whether the observer rated the scan as being of good, moderate or poor quality for reading) had no effect.
