Magnetic resonance imaging scanner reliability for measuring changes in vestibular schwannoma size

Abstract

Objective: To determine the intracranial tumor measurement reliability of three different magnetic resonance imaging machines.

Study design: Neurofibromatosis Type 2 patients were imaged at three different facilities, two studies per facility, for a total of six studies per patient. Seven subjects were imaged.

Setting: Tertiary care center.

Patients: Neurofibromatosis Type 2 patients.

Outcome measure: All tumors were measured by greatest diameter (in millimeters) and volume (in cubic centimeters). Schwannomas were measured in the anteroposterior and mediolateral dimensions (in millimeters), using the petrous ridge as an anatomic landmark.

Results: The reliability of magnetic resonance imaging measurement (greatest diameter, volume) of meningiomas and vestibular schwannomas were analyzed together. There were no statistically significant differences by magnetic resonance imaging machine. There was a trend for one scanner to produce greater differences between Test 1 and Test 2 than the other scanners. The minimal detectable change in tumor size for measuring greatest diameter and volume across scanners was calculated.

Conclusion: The minimal detectable change in greatest diameter (under the study acquisition protocol) was determined to be 1.1 mm. The minimal detectable change in volume (under the study acquisition protocol) was determined to be +/-0.15 cm(3). These results may be used when designing clinical trials using vestibular schwannoma or meningioma size changes as an outcome variable.