The Potential of High Resolution Magnetic Resonance Microscopy in the Pathologic Analysis of Resected Breast and Lymph Tissue

Abstract

Pathologic evaluation of breast specimens requires a fixation and staining procedure of at least 12 hours duration, delaying diagnosis and post-operative planning. Here we introduce an MRI technique with a custom-designed radiofrequency resonator for imaging breast and lymph tissue with sufficient spatial resolution and speed to guide pathologic interpretation and offer value in clinical decision making. In this study, we demonstrate the ability to image breast and lymphatic tissue using 7.0 Tesla MRI, achieving a spatial resolution of 59 × 59 × 94 μm(3) with a signal-to-noise ratio of 15-20, in an imaging time of 56 to 70 minutes. These are the first MR images to reveal characteristic pathologic features of both benign and malignant breast and lymph tissue, some of which were discernible by blinded pathologists who had no prior training in high resolution MRI interpretation.

Figure 1. Specimens were obtained at 7.0 Tesla with T₁ gradient echo sequences using the above custom designed coil/cassette apparatus, which included a three loop parallel wound solenoidal resonator.

A Gd-DTPA solution was contained in the reservoir in which the cassette and sample were immersed. The two polyethylene foam discs supporting the platform helped to dampen scanner vibration.

Figure 2

7.0 Tesla MR image (i) and corresponding H&E stained light microscopy image (ii) of normal breast parenchyma (A), fibroadenoma (B), DCIS (C), IDC and DCIS (D) and ILC (E). An expanded view of the area within the boxes is shown on the right, at 4× magnification. The scale bar at top right is 1.25 mm. A single expanded duct is highlighted in cyan (C). Fat surrounding the IDC mass is identified (blue arrowhead; (D)), appearing black due to fat suppression on MRI. Central debris within DCIS is highlighted (purple arrowhead; (D)). The lateral margin of the ILC mass is delineated in orange (dashed line; (E)).

Figure 3

7.0 Tesla MR image (i) and corresponding H&E stained light microscopy image (ii) of a benign lymph node (A) and a lymph node with carcinoma invasion (B). An expanded view of the area within the box is demonstrated on the right, at 4× magnification. The scale bar at top right is 1.25 mm. The lymph node capsule is highlighted (green arrow; (A,B)). Normal lymph node hilum is highlighted (cyan arrowhead; (A)).

Figure 4. Survey results of the diagnosis, disease (benign vs. malignant) and tissue type (breast vs. lymphatic) utilizing representative 7.0 Tesla MR images of each specimen, in comparison to results for the corresponding light microscopy image (A).

The individual responses for each MR image are depicted in (B), with the correct diagnosis highlighted in gray.