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Effect of Contrast Dose on Diagnostic Performance in DCE-MR Breast Imaging1Radiology, University of Pennsylvania, Philadelphia, PA, United States
Synopsis
A retrospective reader study was performed to assess breast MRI diagnostic performance as a function of contrast dose. There was an increase in sensitivity for malignancy with increasing contrast dose with no significant decrease in specificity. Greater confidence in the lesion assessment was also shown by the inter-observer agreement, which increased at the higher doses. Diagnostic performance of DCE-MR breast imaging was greater when subjects received a higher gadolinium dose than the current standard of 0.10 mmol/kg.
Introduction
Although detection of breast cancer is a widely used application of dynamic contrast enhanced magnetic resonance imaging (DCE-MR), there have been few studies1-3 performed to determine the optimal dose of the gadolinium-based contrast agents (GBCA). The concern over the safety of gadolinium based contrast agents (GBCA) is an important issue4,5 that continues to influence the choice of contrast dosemand may justify the use of lower GBCA doses. However, before coming to that conclusion, the trade-off in diagnostic performance should be understood in order to make an informed risk/benefit decision. The purpose of this study was to assess diagnostic performance of breast MR imaging as a function of gadolinium contrast dose using a retrospective reader study of exams that were acquired during a period of time when the contrast dose was changed from a fixed volume to a weight based calculation.Methods
IRB approval was obtained prior to the start of this study and was HIPAA compliant. One-hundred-fifty MR breast exams were included that were acquired over a period before and after the transition from a fixed volume contrast dose to weight based calculation of dose.. Seventy-five patients received a contrast dose (gadopentetate dimeglumine) by weight of 0.10 mmol/kg and 75 patients were imaged using a fixed volume of 20 ml. Images were acquired at 1.5T using a General Electric Signa (43 exams) or a Siemens Sonata (107 exams). Subjects were placed in the prone position, with the breasts gently compressed within a dedicated bilateral breast coil. T1 and T2 weighted images were acquired followed by a dynamic contrast enhanced series. The DCE series was acquired using a radial fast 3D spoiled gradient-recalled sequence using 512 data samples with 384 projections, and 32 slices of 3 mm thickness. Seventy-five exams were performed unilaterally and the remaining 75 cases were bilateral exams. Scan parameters were: TR=10 ms; TE=4 ms; flip angle = 20°- 45°. Fat signal was suppressed using spectral inversion. A high-resolution baseline volume was acquired followed by three post-contrast volumes acquisitions over the following 6-minute period. Contrast (gadopentetate dimeglumine (Magnevist, Berlex Laboratories, Wayne, NJ) was administered at 1.5 ml/s followed by a saline flush. The images were assessed by two radiologists with performance calculated for each reader as well as a combined assessment. Dose response was measured by comparing performance between cases binned by dose: <=0.10; >0.10; and >0.13 mmol/kg. Statistical significance was calculated using a one-sided Z-test for differences in proportions with inter-observer agreement calculated using Cohen's kappa statistics.Results
The combined reader performance is shown in Table 1. With lesions assessed as “unknown” classified as a positive finding, sensitivity rose from 79% to 95% (p<0.10). With unknown lesions classified as negative, sensitivity rose from 66% to 95% (p<0.01). Inter-observer agreement using assessment categories: benign, malignant, or indeterminate at each dose group (low to high) were 0.46, 0.63 and 0.59. Agreement increased when the indeterminate lesions were classified as negative (k=0.56, 0.79, 0.77 ).
Table 1Combined Reader Performance of DCE-MR Breast Imaging | ||||||
|
| Equivocal Lesions Positive | Equivocal Lesions Negative | ||||
| Dose (mmol/kg) | <0.1 | >0.1 | >0.13 | ≤0.1 | >0.1 | >0.13 |
| Sensitivity | 79% (23/29) | 92% (24/26) | 95% (18/19) | 66% (19/29) | 92% (24/26) | 95% (18/19) |
| Specificity | 53% (26/49) | 72% (33/46) | 70% (26/37) | 65% (32/49) | 87% (40/46) | 86% (32/37) |
| PPV | 50% (23/46) | 65% (24/37) | 62% (18/29) | 53% (19/36) | 80% (24/30) | 78% (18/23) |
| NPV | 81% (26/48) | 94% (33/41) | 96% (26/32) | 76% (32/55) | 95% (40/48) | 97% (32/38) |
| Accuracy | 63% (49/78) | 79% (57/72) | 79% (44/56) | 65% (51/78) | 89% (64/72) | 89% (50/56) |
Conclusion
These data show there is an increase in sensitivity for malignancy with increasing contrast dose. There was no significant decrease in specificity. Greater confidence in the lesion assessment was also shown by the inter-observer agreement, which increased at the higher doses. Diagnostic performance of DCE-MR breast imaging was greater when subjects received a higher gadolinium dose than the current standard of 0.10 mmol/kg.Acknowledgements
This work was supported in part by the Susan G. Komen Breast Cancer Foundation (IMG 2000 224) and the NIH (1RO1-CA90699).References
- Heywang-Kobrunner SH, Haustein J, Pohl C, et al. Contrast-enhanced MR imaging of the breast: comparison of two different doses of gadopentetate dimeglumine. Radiology 1994 191:639–646.
- Jansen SA, Fan X, Yang C, et al. Relating dose of contrast media administered to uptake and washout of malignant lesions on DCEMRI of the breast.. Academic Radiology, 2010 Jan;17(1):24-30.
- Knopp MV, Bourne MW, Sardanelli F, et al. Gadobenate dimeglumine enhanced MRI of the breast: analysis of dose response and comparison with gadopentetate dimeglumine. AJR Am J Roentgenol 2003 181:663–676.
- Grobner, T. Gadolinium–a specific trigger for the development of nephrogenic fibrosing dermopathy and nephrogenic systemic fibrosis? Nephrology, Dialysis and Transplantation, 2006 21(4), 1104–8.
- Marckmann, P., Skov, L., Rossen, K., et al. Nephrogenic Systemic Fibrosis: Suspected Causative Role of Gadodiamide Used for Contrast-Enhanced Magnetic Resonance Imaging. J Am Soc Nephrol, 2006, (17), 2359–2362.
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