An algorithm for incorporating breast MRI into clinical practice

2-4 An Algorithm for Incorporating Breast MRI into Clinical Practice Frederick Kelcz, Ph.D., M.D., Giles E. Santyr, Gregory O. Cron. University of Wisconsin. 2-5 Gadolinium Enhanced MRI of Core Biopsy Proven Fibroadenomas: Histologic Correlation Oliver Pomeroy, M.D., P. Mok, M.D., S. Lester, M.D., Ph.D., D. Adams, M.D., C. Tempany, M.D., F.A. Jolesz, M.D., Brigham & Women's Hospital. Purpose: We performed dynamic Gd-DTPA-enhanced breast MRI on 72 breast lesions to test an algorithm for using MR/to increase the currently low positive predictive value associated with mammographie biopsy. Methods: Dynamic Gd-anhanced breast MR/was performed at 1.5 T on 72 lesions using a dedicated breast coil. The results were classified according to a three step algorithm requiring answers to three questions: (a) Did the lesion enhance?; (b) Aider the initial enhancement was the trend toward increasing or decreasing signal intensity (SO?; and (c) What was the value of the normalized initial slope when the results were fit to a saturation equation? Results: The 72 lesions, all biopsy proven, consisted of 17 cancers, 16 fibroadenomas and 39 benign other lesions. All 26 non-enhancing lesions were benign; all cancers enhanced. 10 of 17 cancers displayed early washout, but only 2 of 2g benign lesions displayed this property. 16 of 17 benign lesions displayed a constant SI increase, a property displayed by only one malignant lesion. The normalized slope was, on the average, three times greater for malignant lesions than for benign lesions. Conclusion: Use of this three-step algorithm would have reduced the number of false negative biopsies from 55 to 5. The price paid is that 3 malignancies would have been misclassified as benign. Overall, MR/resulted in a sensitivity of 82% and a specificity of 91% in regard to breast malignancy. ~URPOSE TO correlate the MRI signal characteristics and enhancement features of breast fibroadenomas with their histologic patterns. M~TERIALS AICD~ODS 13 patients (14 lesions) with core biopsy proven fibroadenomas were imaged using the following pulse sequences; T x SE PRE and POST Gd, T 2 FSE, and dynamic Gd enhanced gradient echo imaging (FSPGR). MR features were correlated with the histologic patterns of stromal cellularity, collagen content, epithelial hyperplasia and number of vessels. RESULTS All lesions were identified on MRI. They ranged in size from 7mm to 3 cm. Ta weighted signal intensity ranged from high (7 cases), intermediates.(2) to low (5). 8 of 9 lesions with high/intermediate T 2 signal demonstrated moderate to marked enhancement with Gd (The Gd bolus in one patient infiltrated). 4 of 5 lesions with low T 2 signal demonstrated minimal to moderate enhancement (one lesion was only imaged on T 2) High/Intermediate T 2 signal correlated with myxoid stroma (8), epithelial hyperplasia (5) and mean number of vessels (mean 50 versus mean 25 for low T2). All lesions with marked gadolinium enhancement (3) had myxoid stroma, whereas the one lesion with minimal enhancement was densely collagenised. CONCLUSION We have demonstrated good correlation between histology and the expected MR signal characteristics, 3-1 Dynamic, Contrast-Enhanced CT and MRI of Focal Liver Lesions: Similarities, Differences and Explanations G. Scott Gazelle, M.D., Giles W. Boland, M.D., Michael J. Lee, M.D., Wiliam W. Mayo-Smith, M.D., Sanjay Saini, M.D., Peter R. Mueller, M.D. Massachusetts General Hospital. 3-2 A Molecular Receptor-Binding Contrast Agent for Magnetic Resonance Imaging of the Liver David R. Vera, Ph.D., Michael H. Buoncore, M.D, Ph.D., Erik R. Wisner, D.V.M., Richard W. Katzberg, M.D., Robert C. Stadalnik, M.D. University of California, Davis Medical Center. Purpose : To compare the enhancement patterns of focal liver lesions on dynamic contrastenhanced CT and MR/. Ma te r i a l s and M e t h o d s : Thirty patients with focal liver lesions underwent both CT and MR/immediately following intravenous contrast administration (diatrizoate or iohexol for CT; Gd-DTPA for MR/). Scans were performed within 2 minutes in all patients; additional delayed scans were performed in 15/30. Images were reviewed by 3 readers blinded to patient identity and lesion diagnosis; each independently recorded the enhancement pattern (none, homogeneous, heterogeneous, linear, single nodule, peripheral nodules, thin rim, thick rim) of each lesion. Readers viewed CT and MR images from each patient on different days; direct comparison was not permitted, lnter-modality and inter-reader variation were analyzed. ReslAlt$: Readers described similar enhancement patterns on CT and MR in 19/30, 17/30, and 14/30 cases (readers A, B, C). Readers agreed about CT enhancement patterns in 22/30 cases; at least 2/3 agreed in 28/30. Readers agreed about MRI enhancement patterns in 17/30 cases; at least 2/3 agreed in 28/30. C o n c l u s i o n : Though presumably representative of the same phenomena, enhancement patterns of liver lesions on CT and MR/using currently available contrast agents differ in up to 83% of patients. Potential explanations will be discussed. PUI'~OSE. A gadolinium complex of polydiethylanetriamian-pentancetie aeid-polyneogalactosylpolylysine (Gd-DTPA-gal-PL) was developed and tested as a paramagnetie contrast agent for magnetic resonance (MR) imaging of the liver. The agent was designed for receptor-mediated uptake by the asialogiycoprotein receptor (ASGP-R), which is unique to hepatoeytes and exhibits high specificity for galaetose-terrninated glyeoconjugates. METHODS. Polylysine was alkylated with a mixed anhydride of DTPA. This product was complexed with gadolinium, and N-alkylated with 3-oxopropyl-l-thio-p-D-galactopyranoside. With this reaction sequence, we prepared a gadolinium complex consisting of 2284 galaetose groups and 858 chelators per polylysine having 2I 36 amino groups. Hepatie enhancement was tested by MR imaging of (n=9) rats with liver-implanted mammary adenocarcinoma before and after injection of 20 0.1). The liver accumulated 90% ofthe Tc-99m-labeled conjugate. CONCLUSION. A molecular paramagnetic ligand to the asialogiycoprotein receptor has been developed for hepatocyte-specific MR contrast enhancement.