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PT  - JOURNAL ARTICLE
AU  - Hanna, S L
AU  - Langston, J W
AU  - Gronemeyer, S A
TI  - Value of subtraction images in the detection of hemorrhagic brain lesions on contrast-enhanced MR images.
DP  - 1991 Jul 01
TA  - American Journal of Neuroradiology
PG  - 681--685
VI  - 12
IP  - 4
4099  - http://www.ajnr.org/content/12/4/681.short
4100  - http://www.ajnr.org/content/12/4/681.full
SO  - Am. J. Neuroradiol.1991 Jul 01; 12
AB  - Contrast-enhanced T1-weighted MR images are known to improve the detection and conspicuity of CNS lesions; however, lesion enhancement may be indistinguishable from contiguous hemorrhagic areas of intrinsically increased signal intensity. In a series of cranial MR studies in 22 pediatric oncologic patients with evidence of subacute hemorrhage, we found that subtracting the unenhanced from the enhanced T1-weighted images was essential in 14 of the cases to visualize and/or characterize the enhanced tissue in the presence of adjacent hemorrhage. In six patients, a nodular pattern of enhancement suggestive of tumor was detected and/or outlined only after subtraction. In eight patients, linear benign-appearing enhancing margins were seen clearly only after subtraction. In the remaining eight patients, the presence and shape of enhancement was verified with subtraction. Subtraction is a useful, simple, and rapid postprocessing procedure that does not increase scan time or require modification of standard pulse sequences. Subtraction separates the enhanced areas from adjacent bright hemorrhage.