MR Tumor Staging for Treatment Decision in Case of Wilms Tumor

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					Clinical Pediatric Imaging                                                                                                                                                                        Pediatric Imaging Clinical

MR Tumor Staging for                                                                                                                      1A           1B

Treatment Decision in Case
of Wilms Tumor
G. Schneider, M.D., Ph.D.; P. Fries, M.D.

Dept. of Diagnostic and Interventional Radiology, Saarland University Hospital, Homburg/Saar, Germany

                                                                                                                                          1C           1D

Introduction                                                                                Patient history
Nephroblastoma – also known as Wilms
tumor – is the most frequent renal
                                              Europe or COG (Children’s Oncology
                                              Group) in North America. Therapy
                                                                                            A 4-year-old girl presented with a large
                                                                                            palpable mass in the left upper quadrant
malignancy in childhood with the high-        includes primary surgery (COG), pre-          and unspecific abdominal pain. Ultra-
est incidence of this tumor within the
fourth year of life. 80% of patients are
                                              operative chemotherapy (SIOP), and/or
                                              adjuvant chemotherapy. If not treated,
                                                                                            sound had already revealed a large
                                                                                            tumor of the left hemiabdomen with
less than 5 years old, however it is a rare   prognosis of a Wilms tumor is poor.           mass effect towards the liver. The
condition in neonates (<1%).                  Independent of prognostic factors such        patient was referred to our MRI depart-
In general, there are no known risk fac-      as stage and grading, the overall out-        ment because of suspicion of Wilms
tors for the development of nephroblas-       come is good and approximately 90% of         tumor.
toma, but it may be associated with rare      all children will be cured.
conditions like Denys-Drash (triad of         Questions for imaging are: a) supporting      MRI protocol
congenital nephropathy, Wilms tumor           the suspicion of a Wilms tumor for initia-    MRI was conducted using a 1.5 Tesla
and intersex disorders), WAGR (also           tion of therapy, b) evaluation of tumor       MAGNETOM Aera with the combination            1E            1 Transversal high-resolution T2w images showing the
called Wilms tumor-aniridia syndrome)         volume, c) contralateral tumor manifes-       of the 18-channel body coil and the inte-                  Wilms tumor (*) and multiple lung metastases (arrows).
and Beckwidth-Wiedeman (giantism              tation and d) lymph nodes metastasis          grated spine coil. For the MRI procedure                   Due to the space occupying aspect of the large tumor, the
associated with tumors and malforma-          or infiltration of neighboring structures     the patient received an intravenous                        residual kidney is swollen (+) and also slight edema of the
tions) syndrome. The incidence is
approx. 1: 100,000 for western coun-
                                              e.g. diaphragm or liver.
                                              Tumor staging has to include at least the
                                                                                            sedation using propofol. The imaging
                                                                                            protocol included diffusion-weighted
                                                                                                                                               *       liver hilum can be seen (arrowheads).

tries including the US, while a lower         whole abdomen and thorax (lung filiae         imaging (DWI, syngo REVEAL), acquired
incidence is reported for Asian countries.    are the most common presentation of           during free breathing, and transversal
If not associated with a syndrome, clini-     metastatic disease). Imaging modalities       T2w TSE and HASTE sequences with
cal symptoms – if present at all – are        used are ultrasound, MRI, and CT in case      navigator triggering.
very often unspecific and abdominal           of lung metastases. Depending on final        A single-shot echo planar diffusion
pain and palpable tumor can be the only       tumor histology, a bone (often scinti-        imaging with Stejskal-Tanner diffusion
findings at the time of diagnosis.            gram) and brain MRI scan have to be           encoding scheme was applied. For
MRI is considered the imaging modality        performed in case of CCSK (clear cell sar-    fat saturation, an inversion recovery
of choice for tumor staging and subse-        coma) and RTK (rhabdoid tumor of the          technique was used. The sequence
quent treatment planning. If imaging is       kidney), too. MRI is recommended inde-        parameters were:
conclusive, often no biopsy is performed      pendent of the above-mentioned reasons
prior to initiation of therapy. Clinical      in any case where a) a caval vein tumor
treatment is according to protocols of        thrombus, b) infiltration of liver and dia-
SIOP (Society of Pediatric Oncology) in       phragm, or c) continuous tumor exten-
                                              sion into the thoraxic cavity is suspected.
                                                                                                                   Continued on page 10

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Clinical Pediatric Imaging                                                                                                                                                                                                                                                       Pediatric Imaging Clinical

2                                                                                                                                                        5A                                                                           5B

     2 Rotating MIP based on high b-value images.
                                                                                                                                                         5C                                                                           5D

3A                                3B                                      3C                                       3D

                                  3E                                       3F                                      3G

                                                                                                                                                         5E                                                                          5F

     3 (A) Coronal DWI MIP. Original b-value images at 0 and 800 s/mm2 (B, C and E, F) as well as calculated b-value at b 1400 s/mm2 (D, G) are
    shown. (Arrows pointing to lung metastases.)

4A                                                                              4B


                                            *                                                                              *
                                                                                                                                                           5 Based on ADC maps and high b-value images (b 1400 s/mm2 is shown), a clear differentiation between residual but swollen kidney
     4 Calculated ADC map (A) and corresponding T2w image (B) demonstrating the tumor heterogeneity. The area marked by the arrows has a clear            tissue (arrows) and the Wilms tumor (arrowhead) is possible. Both types of tissue differ in their cellular density, however, on T2w images
    restriction in diffusibility but based on T2w imaging alone, no differentiation between this area and the one marked with * is possible. While the    no clear differentiation is possible in this case (compare Fig. 1). Nevertheless, not all areas of the tumor are characterized by high signal
    high signal area on T2w and high ADC values may represent cysts or calceal dilation, the area with the high restriction of diffusion represents a     on the very high b-value images, demonstrating well the tumor heterogeneity. (A, B) ADC maps. (C, D, E) b 1400 s/mm2 images. (F) Coro-
    very densely packed areal e.g. mucous tumor cells.                                                                                                    nal thick-slice MPR based on b 1400 s/mm2 images (* spleen).

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Clinical Pediatric Imaging                                                                                                                                                                                                                                             Pediatric Imaging Clinical

6A                                                                                  6B                                                             7A                                                                 7B
                                                                                                                                                                                                                                                                               7 Follow-up
                                                                                                                                                                                                                                                                              examination with
                                                                                                                                                                                                                                                                              CT (A) still showing
                                                                                                                                                                                                                                                                              a small residual
                                                                                                                                                                                                                                                                              lung metastasis
                                                                                                                                                                                                                                                                              (arrow), which can
                                                                                                                                                                                                                                                                              also be visualized
                                                                                                                                                                                                                                                                              by MRI (B). The
                                                                                                                                                                                                                                                                              main tumor is also
                                                                                                                                                                                                                                                                              clearly reduced
                                                                                                                                                                                                                                                                              in its mass after
                                                                                                                                                                                                                                                                              first cycle of
                                                                                                                                                                                                                                                                              (C–F) in caudo-
                                                                                                                                                                                                                                                                              cranial sorting.

                                                                                                                                                   7C                                                                 7D

     6 Corresponding images of the initial ultrasound examination of the Wilms tumor in sagittal (A) and transversal (B) orientation are shown.

Continued from page 6

                                                    Imaging findings
TR 15400 ms, TE 75 ms, TI 180 ms, PAT               A large occupying tumor deriving from              displaced spleen is also within normal
factor of 2, 3-scan trace (averaged), FOV           the lower pole of the left kidney with             age-related range.
309 x 380, matrix 208 x 128 (interpo-               compression of the residual kidney and             On a follow-up study after chemotherapy
lated to 208 x 256), slice thickness 5 mm,          mass effect towards the liver and espe-            and before surgery a tremendous reduc-      7E                                                                 7F
no gap, 4 averages. Real voxel size was             cially the left liver lobe is shown. Due to        tion of tumor size can be noticed. Only
1.5 x 3 x 5 mm3. Two b-values at b 0 and            the mass effect, slight edema of the liver         small residual tumor tissue of one lung
b 800 s/mm2 were acquired. ADC maps                 hilus can be seen. However, the border             metastases is visible on CT and MRI.
and additional high b-value images at               of the mass is well circumscribed and no
b 1400 s/mm2 were calculated auto-                  evidence of diffuse tumor infiltration of          Conclusion
matically by the scanner software, based            the liver, spleen or diaphragm can be              Whole-body imaging in staging of Wilms
on linear signal decay. DWI covered the             seen. Since no encasement of retroperi-            tumor can replace CT imaging and gives
whole body trunk from skull base                    toneal vessels or other structures is seen         all necessary information for therapy
towards upper lower extremities. Acqui-             DD of neuroblastoma can be ruled out.              planning. With the help of newer imag-
sition time was approx. 15 min. For pre-            Also the lumen of the abdominal aorta is           ing modalities in MRI, especially DWI,
sentation and fast overview about tumor             regular and neither a tumor infiltration           the prediction of tumor response needs
spread, a rotating maximum intensity                of the large vessels nor a tumor-throm-            to be evaluated. This can easily be done
projection (MIP) based on b 800 s/mm2               bus can be visualized. The right kidney            by correlating histological data with
was generated.                                      and the other abdominal organs are free            imaging data from patients enrolled in
For detailed morphology and assess-                 of metastases. However, already well               prospective clinical trials. As preopera-
ment of tumor infiltration, navigator               visualized by the MIP DWI, a large tumor           tive chemotherapy is only part of the
triggered T2w TSE was applied for the               mass at the right lung hilum can be seen           SIOP studies such investigations can pre-     References
                                                                                                                                                   1 Kaste, S.C., Dome, J.S., Babyn, P.S., Graf, N.M.,
abdomen including the lower thorax and              with compression of central lung struc-            dominantly be performed in Europe.                                                                  PD Dr. Dr. Günther Schneider
                                                                                                                                                     Grundy, P., Godzinski, J., Levitt, G.A., Jenkinson,
mediastinum. Sequence parameters were               tures and edema of the depending lung                                                            H. 2008 Wilms tumour: Prognostic factors, stag-
                                                                                                                                                                                                           Dept. of Diagnostic and Interventional
TR 3508 ms, TE 102 ms, 2 averages.                  tissue. In addition, at least four addi-                                                                                                               Radiology
                                                                                                                                                     ing, therapy and late effects Pediatric Radiology
                                                                                                                                                                                                           Saarland University Hospital
PAT factor 2, FOV 188 x 250 mm2, matrix             tional lung metastases are detected.                                                             38 (1), pp. 2-17.
                                                                                                                                                                                                           Kirrberger Strasse
269 x 512, slice thickness 6 mm, 20%                No evidence for bone metastases. The                                                           2 Graf, N., Tournade, M.-F., De Kraker, J. 2000 The
                                                                                                                                                                                                           66421 Homburg/Saar
                                                                                                                                                     role of preoperative chemotherapy in the manage-
gap, acquisition time was approx. 8 min.            bright signal of the bone marrow on                                                                                                                    Germany
                                                                                                                                                     ment of Wilms’ tumor: The SIOP studies. Urologic
                                                    high b-value images has to be con-                                                                                                           
                                                                                                                                                     Clinics of North America 27 (3), pp. 443-454.
                                                    sidered as age related. The size of the

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