Effect of thin-section diffusion-weighted MR imaging on stroke diagnosis.
OBJECTIVE
Diffusion-weighted (DW) imaging has limited spatial resolution, especially in the z direction. We decreased the section thickness of DW imaging to 3 mm to determine if this change improves the depiction of small infarcts and if it affects stroke diagnosis.


METHODS
We studied conventional (5-mm section thickness, 1-mm intersection gap) and thin-section (3-mm section thickness, no intersection gap) DW imaging data in 49 patients with symptoms of acute cerebral ischemia. Two radiologists who were not aware of the clinical findings reviewed all images and diagnosed the stroke subtype according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) method. Accuracies of stroke diagnosis with an experienced neuroradiologist and with a second-year radiology resident were compared. To quantify lesion conspicuity, contrast-to-noise ratios (CNRs) were measured. The CNR of thin-section DW imaging was then divided by the CNR of conventional DW imaging to yield the relative CNR (rCNR).


RESULTS
The experienced neuroradiologist made the correct final diagnoses in 78% of cases with conventional DW imaging, improving to 100% with thin-section DW imaging. The resident made the correct diagnoses in 71% of cases with conventional DW imaging, improving to 94% with thin-section DW imaging. Lesion conspicuity was improved on thin-section DW imaging (rCNR = 1.47 +/- 0.63), especially for supratentorial lesions (rCNR = 1.51 +/- 0.63).


CONCLUSIONS
Compared with conventional DW imaging, thin-section DW imaging permitted better lesion conspicuity and more precise stroke diagnosis.
Nakamura
Hisao
H
Department of Radiology, Kyoto Prefectural University of Medicine, Kajii-cyo, Kawaramachi Hirokoji Noboru, Kamigyo-ku, Kyoto City, Japan.
Yamada
Kei
K
Kizu
Osamu
O
Ito
Hirotoshi
H
Yuen
Sachiko
S
Ito
Takaaki
T
Yoshikawa
Kenji
K
Shiga
Kensuke
K
Nakagawa
Masanori
M
Nishimura
Tsunehiko
T
D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008867:Microtomy / Q000592:standards; D008875:Middle Aged; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D020521:Stroke / Q000175:diagnosis*