Diagnosis of cerebral metastases: double-dose delayed CT vs contrast- enhanced MR imaging

• Published in: American journal of neuroradiology : AJNR 1991-03, Vol.12 (2), p.293-300
• Main Authors: Davis, PC, Hudgins, PA, Peterman, SB, Hoffman, JC, Jr
• Format: Article
• Language: English
• Subjects: Adult; Aged; Biological and medical sciences; Brain Neoplasms - diagnosis; Brain Neoplasms - diagnostic imaging; Brain Neoplasms - secondary; Breast Neoplasms - diagnosis; Breast Neoplasms - diagnostic imaging; Comparative Study; Contrast Media; Female; Gadolinium DTPA; Humans; Kidney Neoplasms - diagnosis; Kidney Neoplasms - diagnostic imaging; Lung Neoplasms - diagnosis; Lung Neoplasms - diagnostic imaging; Magnetic Resonance Imaging - methods; Male; Medical sciences; Melanoma - diagnosis; Melanoma - diagnostic imaging; Melanoma - secondary; Middle Aged; Multiple Myeloma - diagnosis; Multiple Myeloma - diagnostic imaging; Neoplasms, Unknown Primary - diagnosis; Neoplasms, Unknown Primary - diagnostic imaging; Neurology; Organometallic Compounds; Pentetic Acid; Tomography, X-Ray Computed - methods; Tumors of the nervous system. Phacomatoses
• ISSN: 0195-6108; 1936-959X

For patients suspected of having cerebral metastases, double-dose delayed CT (DDD-CT) has proved significantly more sensitive than CT scans obtained immediately after administration of a lesser dose of iodinated contrast material. Previous reports confirm the advantages of postcontrast MR imaging over contrast-enhanced CT, but data comparing DDD-CT and contrast-enhanced MR have not been reported. This study describes comparative imaging results in 23 patients who had contrast-enhanced MR imaging to clarify equivocal findings on DDD-CT studies. Contrast-enhanced MR demonstrated more than 67 definite or typical parenchymal metastases. T2-weighted MR revealed more than 40, while DDD-CT revealed only 37 typical metastatic lesions. Three patients had five or fewer lesions on DDD-CT and lesions "too numerous to count" on MR. The frequency of equivocal or unconvincing lesions was similar on DDD-CT (11) and contrast-enhanced MR (10). On T2-weighted images, we noted a substantially higher number of equivocal lesions (19), fewer definite metastases, and a number of definite metastases that had no corresponding lesion on the enhanced studies, confirming the inability of T2-weighted imaging to specifically identify cerebral metastases. In one case, multiple tiny lesions on T2-weighted images were not apparent on DDD-CT scans and were recognized only in retrospect on contrast-enhanced MR images. In this series, MR with enhancement proved superior to DDD-CT for lesion detection, anatomic localization of lesions, and differentiation of solitary vs multiple lesions. Cost-benefit considerations precluded a comparison between the two techniques in all patients suspected of having cerebral metastases.