Table E1. Comparison of Clinical Breast Strain Imaging Studies in the Literature

Study	No. of Subjects	No. of Observers	Blinded Observers	Breast US Experience	Offline Image Formation	Condensed Results
Garra et al (5)	45	1	Yes	Yes	Yes	Lesion size ratio combined with brightness in the strain image help discriminate benign from malignant solid lesions
Hall et al (6)	29	1	No	No	Yes	Small lesion size ratio appears to be unique to benign lesions; some fibroadenomas change brightness as they are deformed
Guiseppetti (23) *	82	2 ^†	Not known	Yes	No	Lesion brightness and brightness uniformity help discriminate benign from malignant solid lesions
Regner et al (18)	89	5	Yes	No ^‡	Yes	Lesion size ratio helps discriminate benign from malignant solid lesions (significant interobserver variability)
Ito et al (9)	111	1	No ^#	Yes	No	Lesion brightness and brightness uniformity helps discriminate benign from malignant solid lesions
Current	98	3	Yes	Yes	Yes	See text

* There were 91 lesions studied in 82 subjects, suggesting the lesions were not independent.

^†It is not clear whether all images were read by a single observer or, if two observers were involved, whether both read all images.

^‡ At least one of the observers had no formal training in breast US imaging.

^# Scoring in the first half of the study was performed with knowledge of the final diagnosis.

Diagnosis	No. Collected (%)	No. Included (%)
Benign (total)	244 (60.5)	47 (48.0)
Fibroadenoma	132 (32.8)	25 (25.5)
Complex cyst	24 (6.0)	5 (5.1)
Normal tissue	19 (4.7)	2 (2.0)
Fibrocystic change	13 (3.2)	3 (3.1)
Stromal fibrosis	13 (3.2)	3 (3.1)
Fat necrosis/scar	8 (2.0)	2 (2.0)
Inflammation	8 (2.0)	2 (2.0)
Intraductal papilloma	6 (1.5)	1 (1.0)
Lymph node (benign)	6 (1.5)	1 (1.0)
Abscess	3 (0.7)	1 (1.0)
Lipoma	3 (0.7)	1 (1.0)
Duct ectasia	3 (0.7)	1 (1.0)
Ductal hyperplasia	1 (0.2)	0 (0.0)
Hematoma	1 (0.2)	0 (0.0)
Galactocele	1 (0.2)	0 (0.0)
Hamartoma	1 (0.2)	0 (0.0)
Tubular adenoma	1 (0.2)	0 (0.0)
Phylloides (benign)	1 (0.2)	0 (0.0)
High-risk lesions (total)	3 (0.7)	1 (1.0)
Atypical ductal hyperplasia	1 (0.2)	1 (1.0)
Lobular carcinoma in situ	2 (0.5)	0 (0.0)
Malignant (total)	156 (38.7)	50 (50)
Invasive ductal carcinoma	133 (33.0)	42 (42.9)
Invasive lobular carcinoma	12 (3.0)	3 (3.1)
Mixed*	4 (1.0)	2 (2.0)
Ductal carcinoma in situ	5 (1.2)	2 (2.0)
Phylloides (malignant)	2 (0.5)	1 (1.0)

Total lesions	403 (100.0)	98 (100.0)

* Mixed = Invasive carcinoma with ductal and lobular features.