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

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.