Purpose: To determine the value of MR imaging in the detection and measurement of tumor size in patients with invasive lobular carcinoma (ILC) compared to mammography and ultrasound.
Materials and methods: From 36 cases of ILC in 34 patients who were surgically treated, the pre-operative imaging measurements, being mammography, ultrasound and contrast enhanced MR, were retrospectively re-evaluated for tumor detection and size. Findings were compared with pathology. Two radiologists were used for evaluation of the mammograms, the other imaging modalities were only evaluated by one radiologist. The Pearsons correlation test was used to determine the correlation between histopathological and imaging measurements for each imaging modality.
Results: For mammography, ultrasound and MRI the false negative scores were respectively 14%, 3% and 0%. The percentage for underestimated, correctly estimated and overestimated measurements on imaging were 56%, 33% and 11% for radiologist 1 and 50%, 33% and 17% for radiologist 2 on mammography. For ultrasound and MRI these percentages were respectively 53%, 47%, 0% and 14%, 75%, 11%. The correlation coefficients for mammography were respectively r = 0.34 (p < 0.05) and r = 0.27 (p > 0.05) for both radiologists, for Ultrasound r = 0.24 (p > 0.05) and for MRI r = 0.81 (p < 0.01).
Conclusion: Of the three imaging modalities contrast enhanced MR has the lowest false negative rate in detecting ILC and has the highest accuracy in measuring the size of the ILC. MR could play a key role in the pre-operative work-up for accurate tumor size determination.