High-dose MR in the evaluation of brain metastases: will increased detection decrease costs?

Brain metastases occur in about 25% of patients ( 1) with cancer and are often diagnosed within the first year after the diagnosis of the primary tumor (2). The treatment of patients with brain metastases usually depends on whether they are solitary or multiple. Surgical resection has been shown to prolong survival by 6 months and improve the quality of life in patients with solitary brain metastases (3). However, surgery is not usually considered appropriate for patients with multiple brain metastases (3, 4). A phase Ill multicenter trial (5) in this issue demonstrates that the sensitivity of magnetic resonance (MR) in the detection of brain metastases can be increased by increasing the dose of contrast. In this trial comparing high-dose (0.3 mmol/kg) with standard-dose (0. 1 mmol/kg) gadolinium, 50% more lesions were detected on the high-dose examinations. Also in this issue, Mayr et at (6) demonstrate that high-dose MR can reduce the cost of patient treatment by eliminating surgery in certain patients with multiple brain metastases. In their study of 27 patients with suspected brain metastases, three craniotomies and two courses of boost radiation therapy in four patients were avoided because multiple brain metastases were detected on high-dose MR. The savings in treatment costs were much greater than the cost of additional contrast material in the high-dose group, $70 644 versus $9126, so that the total net savings were $61 518 and the net savings per patient, $2278. In addition, four patients were spared the morbidity associated with aggressive treatment for solitary brain metastases. Should the standard dose of gadolinium in patients with suspected brain metastases be increased from 0. 1 mmol/kg to 0.3 mmol/kg on the basis of this study? And if so, should similar savings be expected? A key to answering these questions is a consideration of the study conditions, particularly with regard to patient selection, and the effects of advances in diagnostic testing on the classification of disease (7, 8). In the study by Mayr et at (6), increasing the dose of gadolinium increased the detection of brain metastases and caused a "migration" (7) of 10 patients into different categories of brain metastases (Table). With one exception, the migration was toward more advanced disease. Of the 6 patients diagnosed as having no brain metastases by the standard-dose examination, 2 were diagnosed with solitary brain metastases by the high-dose examination. Of the 10 patients diagnosed with solitary brain metastases (9) or resectable pair of metastases (1) by the standarddose examination, 7 were diagnosed with multiple brain metastases by the high-dose examination. Of the 11 patients diagnosed with multiple brain metastases by the standard-dose examination, 1 was diagnosed with a solitary lesion by the highdose examination. Increasing the contrast dose will have different effects on cost depending on the case mix of patients. In the study by Mayr et at (6), more patients migrated out of than into the category of solitary brain metastases, and consequently there were substantial savings in treatment costs. However, three patients who migrated into this category did not incur the cost of surgery or boost radiation therapy because they had contraindications to treatment (two of them had terminal cancer, and one had severe congestive heart failure). In contrast, only one patient with contraindications to aggressive treatment migrated out of this category. Thus, had the patients in the study by Mayr et at (6) not had surgical contraindications, as would be expected outside