Figure 5c:

Images in 34-year-old female volunteer with a history of cold sensitivity localized to the left thumb (blanching and cyanosis). (a, b) Coronal subtraction MIP VFA MR angiograms (repetition time, two R-R intervals; echo time, 10 msec; variable flip angle) obtained after (a) cooling and (b) rewarming. Cold challenge resulted in small vessel caliber and poor visualization of the proper digital arteries. Increased vessel diameter and completion of the superficial arch (arrow) are noted on warming. Note the presence of princeps pollicis beading with focal stenoses (arrowheads). (c) Photographs obtained after the cold challenge show the subject's pale blue left (L) thumb nailbed and normal right (R) thumb for comparison.