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MR Lymphangiography: Imaging Strategies to Optimize the Imaging of Lymph Nodes with Ferumoxtran-10¹

¹ From the Departments of Radiology (M.G.H., M.A.S., M.T., P.F.H.) and Pathology (E.B.), Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114; and General Electric Global Research, Niskayuna, NY (W.T.D., D.J.B., P.J.D.). Recipient of a Cum Laude award for an education exhibit at the 2002 RSNA scientific assembly. Received September 8, 2003; revision requested November 3 and received December 15; accepted December 23. Address correspondence to M.G.H. (e-mail: mharisinghani@partners.org).

View larger version (189K): [in a new window]   Figure 1.  Benign lymph node in a patient with prostate cancer. Axial contrast material-enhanced CT image shows an enlarged right obturator node (arrow). The node was interpreted as metastatic on the basis of the size criterion but proved to be benign at biopsy.

View larger version (180K): [in a new window]   Figure 2.  Malignant lymph node in a patient with renal cancer. Axial contrast-enhanced CT image shows a normal-sized right retrocaval node (arrow). The node was interpreted as benign on the basis of the size criterion but proved to be malignant at surgery.

View larger version (163K): [in a new window]   Figure 3a.  Pathologically proved benign and metastatic pelvic lymph nodes in a patient with bladder cancer. (a) Axial T2*-weighted gradient-echo MR image shows bilateral hyperintense external iliac nodes (arrows), which were characterized as metastatic on the basis of the size criterion. (b) Axial MR image obtained 24 hours after administration of ferumoxtran-10 shows a homogeneous decrease in the signal intensity of the right external iliac node (straight arrow), a finding indicative of a benign origin. However, the left external iliac node (curved arrow), which is enlarged, demonstrates a peripheral drop in signal intensity with preserved central high signal intensity, findings indicative of metastatic infiltration. These findings were confirmed at surgery.

View larger version (139K): [in a new window]   Figure 3b.  Pathologically proved benign and metastatic pelvic lymph nodes in a patient with bladder cancer. (a) Axial T2*-weighted gradient-echo MR image shows bilateral hyperintense external iliac nodes (arrows), which were characterized as metastatic on the basis of the size criterion. (b) Axial MR image obtained 24 hours after administration of ferumoxtran-10 shows a homogeneous decrease in the signal intensity of the right external iliac node (straight arrow), a finding indicative of a benign origin. However, the left external iliac node (curved arrow), which is enlarged, demonstrates a peripheral drop in signal intensity with preserved central high signal intensity, findings indicative of metastatic infiltration. These findings were confirmed at surgery.

View larger version (149K): [in a new window]   Figure 4a.  Sequences for MR imaging with ferumoxtran-10. Axial T1-weighted gradient-echo (a), T2-weighted fast spin-echo (b), and T2*-weighted gradient-echo (c) MR images, obtained after administration of ferumoxtran-10, show a benign left inguinal lymph node (arrow). The node demonstrates homogeneous uptake of ferumoxtran-10 on the T2*-weighted gradient-echo image (c).

View larger version (155K): [in a new window]   Figure 4b.  Sequences for MR imaging with ferumoxtran-10. Axial T1-weighted gradient-echo (a), T2-weighted fast spin-echo (b), and T2*-weighted gradient-echo (c) MR images, obtained after administration of ferumoxtran-10, show a benign left inguinal lymph node (arrow). The node demonstrates homogeneous uptake of ferumoxtran-10 on the T2*-weighted gradient-echo image (c).

View larger version (146K): [in a new window]   Figure 4c.  Sequences for MR imaging with ferumoxtran-10. Axial T1-weighted gradient-echo (a), T2-weighted fast spin-echo (b), and T2*-weighted gradient-echo (c) MR images, obtained after administration of ferumoxtran-10, show a benign left inguinal lymph node (arrow). The node demonstrates homogeneous uptake of ferumoxtran-10 on the T2*-weighted gradient-echo image (c).

View larger version (148K): [in a new window]   Figure 5a.  Fatty hilum of a lymph node at ferumoxtran-10 imaging of the pelvis. (a) Axial T2*-weighted gradient-echo MR image, obtained 24 hours after administration of ferumoxtran-10, shows a right inguinal node with peripheral decreased signal intensity (black arrow) and central high signal intensity (white arrow), an appearance that may be misinterpreted as representing a metastatic deposit. (b) Axial T1-weighted gradient-echo MR image shows that the central area of the node has high signal intensity (top white arrow), which indicates that this area represents the normal fatty hilum of the node. Note the enhancement of the femoral vessels (bottom white arrow) adjacent to the node, an appearance caused by the effect of ferumoxtran-10 on T1. Black arrow = peripheral decreased signal intensity.

View larger version (142K): [in a new window]   Figure 5b.  Fatty hilum of a lymph node at ferumoxtran-10 imaging of the pelvis. (a) Axial T2*-weighted gradient-echo MR image, obtained 24 hours after administration of ferumoxtran-10, shows a right inguinal node with peripheral decreased signal intensity (black arrow) and central high signal intensity (white arrow), an appearance that may be misinterpreted as representing a metastatic deposit. (b) Axial T1-weighted gradient-echo MR image shows that the central area of the node has high signal intensity (top white arrow), which indicates that this area represents the normal fatty hilum of the node. Note the enhancement of the femoral vessels (bottom white arrow) adjacent to the node, an appearance caused by the effect of ferumoxtran-10 on T1. Black arrow = peripheral decreased signal intensity.

View larger version (148K): [in a new window]   Figure 6a.  Benign pelvic lymph node in a patient with bladder cancer. (a) Unenhanced axial T2*-weighted MR image shows a hyperintense right external iliac node (arrow). (b) Axial MR image obtained 8 hours after administration of ferumoxtran-10 shows a heterogeneous drop in signal intensity (arrow), which may be interpreted as malignant infiltration. (c) Delayed axial MR image obtained at the optimal 24-hour interval shows a homogeneous drop in signal intensity within the node (arrow). This finding indicates benignity, which was confirmed at surgery.

View larger version (123K): [in a new window]   Figure 6b.  Benign pelvic lymph node in a patient with bladder cancer. (a) Unenhanced axial T2*-weighted MR image shows a hyperintense right external iliac node (arrow). (b) Axial MR image obtained 8 hours after administration of ferumoxtran-10 shows a heterogeneous drop in signal intensity (arrow), which may be interpreted as malignant infiltration. (c) Delayed axial MR image obtained at the optimal 24-hour interval shows a homogeneous drop in signal intensity within the node (arrow). This finding indicates benignity, which was confirmed at surgery.

View larger version (116K): [in a new window]   Figure 6c.  Benign pelvic lymph node in a patient with bladder cancer. (a) Unenhanced axial T2*-weighted MR image shows a hyperintense right external iliac node (arrow). (b) Axial MR image obtained 8 hours after administration of ferumoxtran-10 shows a heterogeneous drop in signal intensity (arrow), which may be interpreted as malignant infiltration. (c) Delayed axial MR image obtained at the optimal 24-hour interval shows a homogeneous drop in signal intensity within the node (arrow). This finding indicates benignity, which was confirmed at surgery.

View larger version (80K): [in a new window]   Figure 7a.  Benign and malignant axillary lymph nodes in a patient with breast cancer. Axial MR images, obtained with a 3-mm section thickness before (a) and after (b) administration of ferumoxtran-10, show a benign axillary node (black arrow) and an adjacent malignant node (white arrow). On the contrast-enhanced image (b), the benign node demonstrates a homogeneous drop in signal intensity (black arrow), whereas the malignant node remains hyperintense (white arrow).

View larger version (90K): [in a new window]   Figure 7b.  Benign and malignant axillary lymph nodes in a patient with breast cancer. Axial MR images, obtained with a 3-mm section thickness before (a) and after (b) administration of ferumoxtran-10, show a benign axillary node (black arrow) and an adjacent malignant node (white arrow). On the contrast-enhanced image (b), the benign node demonstrates a homogeneous drop in signal intensity (black arrow), whereas the malignant node remains hyperintense (white arrow).

View larger version (140K): [in a new window]   Figure 8a.  Pathologically proved benign lymph node in a patient with prostate cancer. Axial MR images, obtained with a 3-mm section thickness before (a) and after (b) administration of ferumoxtran-10, show a node (circle) with peripheral uptake of contrast material and a prominent central fatty hilum.

View larger version (100K): [in a new window]   Figure 8b.  Pathologically proved benign lymph node in a patient with prostate cancer. Axial MR images, obtained with a 3-mm section thickness before (a) and after (b) administration of ferumoxtran-10, show a node (circle) with peripheral uptake of contrast material and a prominent central fatty hilum.

View larger version (146K): [in a new window]   Figure 9.  Use of an alternate imaging plane. Oblique sagittal T2-weighted MR image of the axilla shows the anatomic location of a metastatic lymph node (black arrow) in relation to the primary tumor (white arrow).

View larger version (19K): [in a new window]   Figure 10.  Mz versus 1/T1. This relationship, which is called the T1 weighting, depends on the TR and flip angle. Traces a-d are the result of the TR-flip angle combinations in the Table. They show that raising the TR from to seconds (from a to b) changes the T1 weighting greatly. Changing the flip angle from 20° to 35° (from a to c) does the same. However, changing both the TR and the flip angle (from a to d) has almost no effect on the T1 weighting.

View larger version (169K): [in a new window]   Figure 11.  Efficient acquisition packing. The time required to excite a section and then observe it can be called TRmin. (TRmin is generally somewhat longer than the TE.) Diagram shows that setting TR to 3 · TRmin allows collection of three sections at once, whereas a TR of 9 · TRmin allows collection of nine sections at once. Both choices keep the imager busy and produce the same number of images per minute. Imaging nine sections in groups of three with a TR of 3 · TRmin is equally efficient. However, imaging four sections with a TR of 3 · TRmin leaves idle time, as would imaging any other number of sections not divisible by 3.

View larger version (118K): [in a new window]   Figure 12a.  Optimization of imaging parameters. Axial T2*-weighted MR imaging of the pelvis was performed after administration of ferumoxtran-10. (a) Image obtained before technique optimization (TR = 250 msec, TE = 24 msec, flip angle = 17°, two signals acquired). (b) Image obtained after technique optimization (TR = 2,100 msec, TE = 24 msec, flip angle = 70°, two signals acquired). Note the higher SNR and the better demonstration of the pelvic anatomy. Arrow = benign right obturator node.

View larger version (122K): [in a new window]   Figure 12b.  Optimization of imaging parameters. Axial T2*-weighted MR imaging of the pelvis was performed after administration of ferumoxtran-10. (a) Image obtained before technique optimization (TR = 250 msec, TE = 24 msec, flip angle = 17°, two signals acquired). (b) Image obtained after technique optimization (TR = 2,100 msec, TE = 24 msec, flip angle = 70°, two signals acquired). Note the higher SNR and the better demonstration of the pelvic anatomy. Arrow = benign right obturator node.

View larger version (144K): [in a new window]   Figure 13a.  Optimal TE for imaging with ferumoxtran-10. Axial T2*-weighted MR imaging of the pelvis was performed in a patient with prostate cancer after administration of ferumoxtran-10. (a) Image obtained with a TE of 14 msec shows a left external iliac node with central heterogeneity (arrow), a finding that may be interpreted as representing metastatic infiltration. (b) Image obtained with a TE of 24 msec at the same time as a shows a more homogeneous drop in signal intensity (arrow). This finding indicates benignity, which was proved at pathologic analysis.

View larger version (134K): [in a new window]   Figure 13b.  Optimal TE for imaging with ferumoxtran-10. Axial T2*-weighted MR imaging of the pelvis was performed in a patient with prostate cancer after administration of ferumoxtran-10. (a) Image obtained with a TE of 14 msec shows a left external iliac node with central heterogeneity (arrow), a finding that may be interpreted as representing metastatic infiltration. (b) Image obtained with a TE of 24 msec at the same time as a shows a more homogeneous drop in signal intensity (arrow). This finding indicates benignity, which was proved at pathologic analysis.

View larger version (207K): [in a new window]   Figure 14.  Mapping of lymph nodes in a patient with prostate cancer. Surface-rendered 3D MR image shows the iliac vessels, distal aorta, and inferior vena cava, which are enhanced due to the effect of ferumoxtran-10 on T1. Malignant nodes are coded in red (arrows), thus showing their relationships to the major vessels.

View larger version (126K): [in a new window]   Figure 15a.  Quantitative estimation of T2* in a benign lymph node. The T2* value was computed with a customized semiautomated segmentation algorithm. Axial dual-TE T2*-weighted gradient-echo MR images, obtained before (a) and after (b) administration of ferumoxtran-10, show a benign node (arrow), which is outlined by a region of interest. The node demonstrates a considerable drop in its T2* value on the contrast-enhanced image (b).

View larger version (129K): [in a new window]   Figure 15b.  Quantitative estimation of T2* in a benign lymph node. The T2* value was computed with a customized semiautomated segmentation algorithm. Axial dual-TE T2*-weighted gradient-echo MR images, obtained before (a) and after (b) administration of ferumoxtran-10, show a benign node (arrow), which is outlined by a region of interest. The node demonstrates a considerable drop in its T2* value on the contrast-enhanced image (b).