LAUSR

ObjectivesTo prospectively determine the feasibility of preoperative supine breast MRI in breast cancer patients scheduled for oncoplastic breast-conserving surgery.MethodsIn addition to a diagnostic prone breast MRI, a supplementary supine MRI was performed with the patient in the surgical position including skin markers. Tumours’ locations were ink-marked on the skin according to findings obtained from supine MRI. Changes in tumours’ largest diameter and locations between prone and supine MRI were measured and compared to histology. Nipple-to-tumour and tumour-to-chest wall distances were also measured. Tumours and suspicious areas were surgically removed according to skin ink-markings. The differences between MRI measurements with reference to histopathology were evaluated with the paired-sample t test.ResultsFourteen consecutive patients, 15 breasts and 27 lesions were analysed. Compared to histology, prone MRI overestimated tumour size by 47.1% (p = 0.01) and supine MRI by 14.5% (p = 0.259). In supine MRI, lesions’ mean diameters and areas were smaller compared to prone MRI (– 20.9%, p = 0.009 and – 38.3%, p = 0.016, respectively). This difference in diameter was more pronounced in non-mass lesions (– 31.2%, p = 0.031) compared to mass lesions (– 9.2%, p = 0.009). Tumours’ mean distance from chest wall diminished by 69.4% (p < 0.001) and from nipple by 18.2% (p < 0.001). Free microscopic margins were achieved in first operation in all patients.ConclusionsSupine MRI in the surgical position is feasible and useful in the precise localisation of prone MRI-detected lesions and provides a helpful tool to implement in surgery. Supine MRI more accurately determines tumours’ size and location and might have an important role to diminish overestimations.Key Points•Breath-hold supine breast MRI is feasible using commercially available coils and sequences.•Size and area of lesions on MRI were consistently smaller when measured from the supine position as compared to the prone position.•Supine breast MRI is useful in the precise preoperative localisation of prone MRI-detected lesions.•