Table 4.

Histological characteristics of MNU induced rat breast pre-treatment tumors under magnification × 400 microscopy equipped with micrometer. Different premalignancy and malignant characteristics and cytomorphology characteristics were co-registered with IR sodium signal intensities. Level of brightness is shown as + sign on MRI gray scale.

Sodium MRI signal Intensity		Histomorphology	Tumor characteristics
SQ Na MRI	IR Na MRI	Tumor features	Tumor stage
			Pre-malignant stage:
isointense dark/gray	++ +	Viable Active necrosis	Intraductal proliferation, ductal hyperplacia, apoptosis
			Malignant stage:
gray	++++	apoptosis	Transformation stage
+++	bright/gray	apoptosis	Carcinoma (papillary; invasive comedo and cribriform)
++++	dark	Cyst	sarcoma, neoplasia