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Adding in Vivo Quantitative ¹H MR Spectroscopy to Improve Diagnostic Accuracy of Breast MR Imaging: Preliminary Results of Observer Performance Study at 4.0 T¹

¹ From the Department of Radiology, Center for Magnetic Resonance Research Medical School, 2021 Sixth St SE, Minneapolis, MN 55455 (S.M., P.J.B., E.H.B., M.G.P., M.G.). The complete list of author affiliations appears at the end of this article. From the 2004 RSNA Annual Meeting. Received May 7, 2004; revision requested Jul 8; revision received Sep 15; accepted Oct 12. Supported by NIH grants RR08079, CA92004, and RR00400; Tickle Family Land Grant Endowment in Breast Cancer Research; PHS Cancer Center Support grant P30 CA77398; and Lillian Quist-Joyce Henline Chair in Biomedical Research. Address correspondence to M.G. (e-mail: gar{at}cmrr.umn.edu).

View larger version (147K): [in a new window]   Figure 1a. (a) Sample display of sagittal high-spatial-resolution 3D fat-suppressed fast low-angle shot breast MR images (13.5/4.1). Each row corresponds to a single section of the breast. Images acquired before (left column) and 7 minutes after (middle column) gadopentetate dimeglumine injection and with subtraction (right column) are shown. Arrow points to the lesion to be evaluated by each reader. (b) Time–signal intensity (SI) curve (top) for the lesion depicted in a and corresponding two-dimensional MR images (bottom). The signal intensity for each case was normalized to 1. Each two-dimensional image corresponds to one signal intensity data point on the time–signal intensity curve.

View larger version (47K): [in a new window]   Figure 1b. (a) Sample display of sagittal high-spatial-resolution 3D fat-suppressed fast low-angle shot breast MR images (13.5/4.1). Each row corresponds to a single section of the breast. Images acquired before (left column) and 7 minutes after (middle column) gadopentetate dimeglumine injection and with subtraction (right column) are shown. Arrow points to the lesion to be evaluated by each reader. (b) Time–signal intensity (SI) curve (top) for the lesion depicted in a and corresponding two-dimensional MR images (bottom). The signal intensity for each case was normalized to 1. Each two-dimensional image corresponds to one signal intensity data point on the time–signal intensity curve.

View larger version (22K): [in a new window]   Figure 2. ROC curve generated from the tCho concentration measured in the 55 lesions evaluated in the observer performance study. With a tCho concentration cutoff point of 1.05 mmol/kg, the accuracy—expressed as the area under the ROC curve (Az)—was 83%; the sensitivity, 69%; and the specificity, 90%.

View larger version (26K): [in a new window]   Figure 3a. (a–d) ROC curves for the four readers based on the BI-RADS categories assigned to the lesions by each reader. On each graph, the dashed line represents the ROC curve generated from the initial interpretations, which were based on the morphologic features and time–signal intensity curves of the lesions, and the solid line represents the ROC curve generated from the second interpretations, which were based on the morphologic features, time–signal intensity curves, and tCho concentrations of the lesions. Note that the accuracy (expressed as area under ROC curve) of the interpretations made by also assessing tCho measurements (solid lines) is higher than the accuracy of the interpretations made without assessing tCho measurements (dashed lines).

View larger version (25K): [in a new window]   Figure 3b. (a–d) ROC curves for the four readers based on the BI-RADS categories assigned to the lesions by each reader. On each graph, the dashed line represents the ROC curve generated from the initial interpretations, which were based on the morphologic features and time–signal intensity curves of the lesions, and the solid line represents the ROC curve generated from the second interpretations, which were based on the morphologic features, time–signal intensity curves, and tCho concentrations of the lesions. Note that the accuracy (expressed as area under ROC curve) of the interpretations made by also assessing tCho measurements (solid lines) is higher than the accuracy of the interpretations made without assessing tCho measurements (dashed lines).

View larger version (26K): [in a new window]   Figure 3c. (a–d) ROC curves for the four readers based on the BI-RADS categories assigned to the lesions by each reader. On each graph, the dashed line represents the ROC curve generated from the initial interpretations, which were based on the morphologic features and time–signal intensity curves of the lesions, and the solid line represents the ROC curve generated from the second interpretations, which were based on the morphologic features, time–signal intensity curves, and tCho concentrations of the lesions. Note that the accuracy (expressed as area under ROC curve) of the interpretations made by also assessing tCho measurements (solid lines) is higher than the accuracy of the interpretations made without assessing tCho measurements (dashed lines).

View larger version (27K): [in a new window]   Figure 3d. (a–d) ROC curves for the four readers based on the BI-RADS categories assigned to the lesions by each reader. On each graph, the dashed line represents the ROC curve generated from the initial interpretations, which were based on the morphologic features and time–signal intensity curves of the lesions, and the solid line represents the ROC curve generated from the second interpretations, which were based on the morphologic features, time–signal intensity curves, and tCho concentrations of the lesions. Note that the accuracy (expressed as area under ROC curve) of the interpretations made by also assessing tCho measurements (solid lines) is higher than the accuracy of the interpretations made without assessing tCho measurements (dashed lines).

View larger version (26K): [in a new window]   Figure 4a. (a–d) ROC curves for the four readers based on the percentage probabilities of malignancy (0%–100%) assigned to the lesions by each reader. On each graph, the dashed line represents the ROC curve generated from the initial interpretations, which were based on the morphologic features and time–signal intensity curves of the lesions, and the solid line represents the ROC curve generated from the second interpretations, which were based on the morphologic features, time–signal intensity curves, and tCho concentrations of the lesions. Note that the accuracy (expressed as area under ROC curve) of the interpretations made by also assessing tCho measurements (solid lines) is higher than the accuracy of the interpretations made without assessing tCho measurements (dashed lines).

View larger version (26K): [in a new window]   Figure 4b. (a–d) ROC curves for the four readers based on the percentage probabilities of malignancy (0%–100%) assigned to the lesions by each reader. On each graph, the dashed line represents the ROC curve generated from the initial interpretations, which were based on the morphologic features and time–signal intensity curves of the lesions, and the solid line represents the ROC curve generated from the second interpretations, which were based on the morphologic features, time–signal intensity curves, and tCho concentrations of the lesions. Note that the accuracy (expressed as area under ROC curve) of the interpretations made by also assessing tCho measurements (solid lines) is higher than the accuracy of the interpretations made without assessing tCho measurements (dashed lines).

View larger version (29K): [in a new window]   Figure 4c. (a–d) ROC curves for the four readers based on the percentage probabilities of malignancy (0%–100%) assigned to the lesions by each reader. On each graph, the dashed line represents the ROC curve generated from the initial interpretations, which were based on the morphologic features and time–signal intensity curves of the lesions, and the solid line represents the ROC curve generated from the second interpretations, which were based on the morphologic features, time–signal intensity curves, and tCho concentrations of the lesions. Note that the accuracy (expressed as area under ROC curve) of the interpretations made by also assessing tCho measurements (solid lines) is higher than the accuracy of the interpretations made without assessing tCho measurements (dashed lines).

View larger version (26K): [in a new window]   Figure 4d. (a–d) ROC curves for the four readers based on the percentage probabilities of malignancy (0%–100%) assigned to the lesions by each reader. On each graph, the dashed line represents the ROC curve generated from the initial interpretations, which were based on the morphologic features and time–signal intensity curves of the lesions, and the solid line represents the ROC curve generated from the second interpretations, which were based on the morphologic features, time–signal intensity curves, and tCho concentrations of the lesions. Note that the accuracy (expressed as area under ROC curve) of the interpretations made by also assessing tCho measurements (solid lines) is higher than the accuracy of the interpretations made without assessing tCho measurements (dashed lines).

View larger version (51K): [in a new window]   Figure 5a. Breast MR imaging case in which 1H MR spectroscopic findings led to altered treatment recommendations. (a) Sagittal high-spatial-resolution 3D fat-suppressed fast low-angle shot MR images of the breast (13.5/4.1) obtained before (left) and 7 minutes after (middle) gadopentetate dimeglumine injection and with subtraction (right) show an 8.3-cm3 lesion. The box surrounding the lesion depicts the MR spectroscopic voxel. (b) Time–signal intensity (SI) curve measured from the lesion depicted in a. All four readers described this curve as showing slow enhancement during the initial phase followed by an enhancement plateau or persistent enhancement during the delayed phase. After evaluating the morphologic features and time–signal intensity curve of the lesion, three of the four readers did not recommend biopsy; rather, they recommended a 6-month follow-up examination. The fourth reader recommended biopsy. (c) 1H MR spectra measured from the lesion. The spectral peaks of mobile lipid, water, and tCho are labeled. The lines above and below the tCho peak represent the fitted tCho peak and the residual of the fit, respectively. The mean tCho concentration measured from this lesion was 1.78 mmol/kg ± 0.56. When the tCho measurement was presented to the readers in the second interpretation, three of the four readers changed their decision and recommended biopsy; the fourth reader kept the recommendation of biopsy. This patient received a diagnosis of invasive ductal carcinoma.

View larger version (7K): [in a new window]   Figure 5b. Breast MR imaging case in which 1H MR spectroscopic findings led to altered treatment recommendations. (a) Sagittal high-spatial-resolution 3D fat-suppressed fast low-angle shot MR images of the breast (13.5/4.1) obtained before (left) and 7 minutes after (middle) gadopentetate dimeglumine injection and with subtraction (right) show an 8.3-cm3 lesion. The box surrounding the lesion depicts the MR spectroscopic voxel. (b) Time–signal intensity (SI) curve measured from the lesion depicted in a. All four readers described this curve as showing slow enhancement during the initial phase followed by an enhancement plateau or persistent enhancement during the delayed phase. After evaluating the morphologic features and time–signal intensity curve of the lesion, three of the four readers did not recommend biopsy; rather, they recommended a 6-month follow-up examination. The fourth reader recommended biopsy. (c) 1H MR spectra measured from the lesion. The spectral peaks of mobile lipid, water, and tCho are labeled. The lines above and below the tCho peak represent the fitted tCho peak and the residual of the fit, respectively. The mean tCho concentration measured from this lesion was 1.78 mmol/kg ± 0.56. When the tCho measurement was presented to the readers in the second interpretation, three of the four readers changed their decision and recommended biopsy; the fourth reader kept the recommendation of biopsy. This patient received a diagnosis of invasive ductal carcinoma.

View larger version (16K): [in a new window]   Figure 5c. Breast MR imaging case in which 1H MR spectroscopic findings led to altered treatment recommendations. (a) Sagittal high-spatial-resolution 3D fat-suppressed fast low-angle shot MR images of the breast (13.5/4.1) obtained before (left) and 7 minutes after (middle) gadopentetate dimeglumine injection and with subtraction (right) show an 8.3-cm3 lesion. The box surrounding the lesion depicts the MR spectroscopic voxel. (b) Time–signal intensity (SI) curve measured from the lesion depicted in a. All four readers described this curve as showing slow enhancement during the initial phase followed by an enhancement plateau or persistent enhancement during the delayed phase. After evaluating the morphologic features and time–signal intensity curve of the lesion, three of the four readers did not recommend biopsy; rather, they recommended a 6-month follow-up examination. The fourth reader recommended biopsy. (c) 1H MR spectra measured from the lesion. The spectral peaks of mobile lipid, water, and tCho are labeled. The lines above and below the tCho peak represent the fitted tCho peak and the residual of the fit, respectively. The mean tCho concentration measured from this lesion was 1.78 mmol/kg ± 0.56. When the tCho measurement was presented to the readers in the second interpretation, three of the four readers changed their decision and recommended biopsy; the fourth reader kept the recommendation of biopsy. This patient received a diagnosis of invasive ductal carcinoma.

View larger version (59K): [in a new window]   Figure 6a. Breast MR imaging case in which the measured tCho concentration did not lead to a change in the recommended lesion management. (a) Sagittal high-spatial-resolution 3D fat-suppressed fast low-angle shot MR images of the breast (13.5/4.1) obtained before (left) and 7 minutes after (middle) gadopentetate dimeglumine injection and with subtraction (right) show a 0.39-cm3 lesion. The box surrounding the lesion depicts the MR spectroscopic voxel. (b) Time–signal intensity (SI) curve measured from the lesion depicted in a. All four readers described this curve as showing fast enhancement during the initial phase followed by an enhancement plateau during the delayed phase. After evaluating the morphologic features and time–signal intensity curve of the lesion, all four readers recommended biopsy. (c) 1H MR spectra measured from the lesion. The spectral peaks of mobile lipids, water, and tCho are labeled. The line above the tCho peak represents the minimal tCho concentration that is detectable with use of the quantification procedure. The mean tCho concentration measured from this lesion was 0 mmol/kg ± 1.73. When the tCho measurement was presented to the four readers in the second interpretation, none of them changed the recommendation of biopsy. This patient received a diagnosis of invasive ductal carcinoma.

View larger version (8K): [in a new window]   Figure 6b. Breast MR imaging case in which the measured tCho concentration did not lead to a change in the recommended lesion management. (a) Sagittal high-spatial-resolution 3D fat-suppressed fast low-angle shot MR images of the breast (13.5/4.1) obtained before (left) and 7 minutes after (middle) gadopentetate dimeglumine injection and with subtraction (right) show a 0.39-cm3 lesion. The box surrounding the lesion depicts the MR spectroscopic voxel. (b) Time–signal intensity (SI) curve measured from the lesion depicted in a. All four readers described this curve as showing fast enhancement during the initial phase followed by an enhancement plateau during the delayed phase. After evaluating the morphologic features and time–signal intensity curve of the lesion, all four readers recommended biopsy. (c) 1H MR spectra measured from the lesion. The spectral peaks of mobile lipids, water, and tCho are labeled. The line above the tCho peak represents the minimal tCho concentration that is detectable with use of the quantification procedure. The mean tCho concentration measured from this lesion was 0 mmol/kg ± 1.73. When the tCho measurement was presented to the four readers in the second interpretation, none of them changed the recommendation of biopsy. This patient received a diagnosis of invasive ductal carcinoma.

View larger version (15K): [in a new window]   Figure 6c. Breast MR imaging case in which the measured tCho concentration did not lead to a change in the recommended lesion management. (a) Sagittal high-spatial-resolution 3D fat-suppressed fast low-angle shot MR images of the breast (13.5/4.1) obtained before (left) and 7 minutes after (middle) gadopentetate dimeglumine injection and with subtraction (right) show a 0.39-cm3 lesion. The box surrounding the lesion depicts the MR spectroscopic voxel. (b) Time–signal intensity (SI) curve measured from the lesion depicted in a. All four readers described this curve as showing fast enhancement during the initial phase followed by an enhancement plateau during the delayed phase. After evaluating the morphologic features and time–signal intensity curve of the lesion, all four readers recommended biopsy. (c) 1H MR spectra measured from the lesion. The spectral peaks of mobile lipids, water, and tCho are labeled. The line above the tCho peak represents the minimal tCho concentration that is detectable with use of the quantification procedure. The mean tCho concentration measured from this lesion was 0 mmol/kg ± 1.73. When the tCho measurement was presented to the four readers in the second interpretation, none of them changed the recommendation of biopsy. This patient received a diagnosis of invasive ductal carcinoma.