Simplified intravoxel incoherent motion DWI for differentiating malignant from benign breast lesions

European Radiology Experimental

Table 1 Overview of lesion types (n = 191)

Group	Type of lesion	Number
A	Benign lesions with no or non-suspicious contrast-enhancement:	56
	1) Simple cyst (n = 20), seroma after biopsy or surgery (n = 3)	23
	2) Complicated (haemorrhagic/proteinaceous) cyst	6
	3) Haematoma	7
	4) Normal fibroglandular tissue without contrast-enhancement	14
	5) Normal fibroglandular tissue with non-suspicious contrast-enhancement	6
B	Benign lesions with suspicious contrast-enhancement:	30
	6) Fibroadenoma (n = 11), fibrocystic mastopathy (n = 10), adenomyoepithelioma (n = 1)	22
	7) Syringomatous adenoma (n = 1), intraductal papilloma (n = 1), sclerosing adenosis (n = 1)	3
	8) Flat epithelial atypia	1
	9) Intramammary lymph node	4
C	Malignant lesions with suspicious contrast-enhancement:	105
	10) Invasive carcinoma G1 (6 ductal, 1 tubular)	7
	11) Invasive carcinoma G2 (23 ductal, 16 lobular, 1 ductolobular, 1 ductal mucinous, 1 other)	42
	12) Invasive carcinoma G3 (34 ductal, 1 lobular, 2 mixed, 2 necrotic, 4 other)	43
	13) Invasive carcinoma with unknown grading (1 ductal)	1
	14) Ductal carcinoma in situ (1 G2, 9 G3)	10
	15) Intramammary lymph node metastases	2

Group A was composed of benign lesions with hyperintensity on diffusion-weighted imaging (DWI) with b = 800 s/mm² and no or non-suspicious contrast-enhancement according to the morphologic and kinetic features defined in the Breast Imaging-Reporting and Data System MRI lexicon [42] (n = 56). Group B was composed of benign lesions with suspicious contrast-enhancement (n = 30). Group C was composed of malignant lesions, which were all with suspicious contrast-enhancement (n = 105). All lesions with suspicious contrast enhancement (groups B and C) were hyperintense on DWI with b = 800 s/mm². The diagnosis of group B and C lesions was established on the basis of histopathological examination of surgical or core needle biopsy according to the World Health Organization classification of breast tumours [43] or follow-up investigations with a minimum interval time of 12 months. The diagnosis of group A lesions was established by DCE-MRI and confirmed by ultrasound and follow-up with the exception of 4 patients (no follow-up avilable)
DCE Dynamic contrast enhancement, MRI Magnetic resonance imaging