MR-guided interventional procedures: a review.

Magnetic resonance imaging (MRI) has emerged as a potential guidance tool for a variety of procedures. Diagnostic and therapeutic procedures using either open surgical or percutaneous access are performed. They span from simple lesion targeting and biopsy to complex applications requiring multiple tasks performed simultaneously or in rapid succession. These tasks include instrument guidance and therapy monitoring as well as procedural follow-up. The interventional use of MRI (IMRI) is increasing steadily. This article reviews the prerequisites, systems, and clinical interventional procedures of IMRI.

Dynamics of contrast enhancement in MR imaging and power Doppler ultrasonography of solid breast lesions.

PURPOSE: To evaluate the dynamics of contrast enhancement in solid breast lesions at contrast-enhanced MR imaging and power Doppler ultrasonography (US) and to compare the methods to histology and to each other. MATERIAL AND METHODS: Forty breast lesions were prospectively examined with dynamic MR and power Doppler US. Time-signal intensity curves of enhancement were obtained for both methods. The shape of the curve was analyzed to be benign, indeterminate or malignant. The curves were also analyzed quantitatively by calculating the slope of the curve and the area under the curve (both methods), relative enhancement (MR), and time to peak (US). The lesions were divided into malignant lesions, fibroadenomas, and other benign lesions. The results were compared to histology. RESULTS: In the subjective analysis of the MR curve in differentiating between benign and malignant lesions the accuracy was 90%. The MR curve also enabled differentiation between fibroadenomas and malignancies. The accuracy of the US curve was 38%. Quantitatively, statistically significant differences were found using all the MR variables, except between malignancies and fibroadenomas. Using the US variables, no significant difference was found between the groups. CONCLUSION: The dynamics of contrast-enhanced MR were reliable in the differential diagnosis of solid breast lesions, but contrast-enhanced power Doppler US was of limited value.

B-mode, power Doppler and contrast-enhanced power Doppler ultrasonography in the diagnosis of breast tumors.

PURPOSE: To investigate the role of B-mode and unenhanced and enhanced power Doppler ultrasonography (US) in differentiating solid breast lesions, and to find out whether morphologically different tumors differ in terms of vascularity. MATERIAL AND METHODS: Sixty-five lesions, indeterminate or suggestive of malignancy after mammography were prospectively examined with B-mode and unenhanced and enhanced power Doppler US. The lesions were classified as benign, indeterminate or malignant at B-mode, and as benign or malignant at power Doppler US. The results were compared to the histologic diagnoses. Vascularity was analyzed also quantitatively to find out whether threshold values for differential diagnostics could be set. RESULTS: The sensitivity, specificity, and overall accuracy of the morphologic evaluation were 100%, 10%, and 57%, respectively. Rounded lesions were more vascular than spiculated lesions, but vascular assessment was only helpful when it supported a benign morphology. In quantitative analysis, due to the overlap between the benign and malignant lesions, no threshold values could be set. CONCLUSION: Morphologic criteria were useful in characterizing malignant lesions, but the large proportion of indeterminate findings decreased the specificity of US. Neither unenhanced, nor enhanced power Doppler US was able to improve diagnostic accuracy.

Contribution of ultrasonography and fine-needle aspiration cytology to the differential diagnosis of palpable solid breast lesions.

PURPOSE: To define the role of ultrasonography (US) and fine-needle aspiration biopsy (FNAB) relative to mammography in differentiating between benign and malignant palpable solid breast lesions, and to assess the contribution of FNAB cytology to the delay between referral and the definitive diagnosis of breast cancer. MATERIAL AND METHODS: We retrospectively reviewed the mammograms and US images of 84 palpable breast lesions, 63 of them also blindly. The lesions were classified as benign, indeterminate or malignant by both modalities. The results were compared with histologic diagnoses. The cytologic reports of 57 lesions were reviewed and compared to the final diagnoses. The delay from referral until diagnosis was calculated for each case. RESULTS: Eighty-one of the 84 lesions (96%) were visible as a local abnormality at US. Fifty-two of the 53 cancers were seen as a tumor (n=51) or an architectural distortion (n=1). In the blinded analysis, the sensitivity of FNAB cytology was 92%, specificity 83%, and overall accuracy 88%. There were no false-negative malignancies in the three modalities combined. The delay until the date of the final diagnosis was shorter in the group with a cytologic diagnosis positive for malignancy. CONCLUSION: Malignancy is unlikely if the US, mammographic and cytologic findings of a palpable breast lesion are all benign. Active and critical use of these three modalities could cut down the number of surgical biopsies of benign breast lesions and provide prompt surgical treatment for malignant lesions.