Case Reports
PREOPERATIVE MAGNETIC RESONANCE IMAGING OF VENA CAVAL TUMOR THROMBI: EXPERIENCE WITH 5 CASES
T. RAND PRITCHETT, JANAK K. RAVAL, ROBERT C. BENSON, GARY LIESKOVSKY, PATRICK M. COLLETTI, WILLIAM D. BOSWELL JR AND DONALD G. SKINNER
From the Division of Urology and Department of Radiology, University of Southern California School of Medicine, Los Angeles, California
ABSTRACT
Magnetic resonance scans were performed preoperatively in 5 patients who underwent surgical removal of renal or adrenal tumors with direct extension of the tumor into the vena cava. Of the patients 4 had renal cell carcinoma and 1 had adrenocortical carcinoma. Magnetic resonance imaging staged correctly the level of vena caval tumor thrombus involvement in 4 patients and missed the presence of right atrial tumor extension in 1. This noninvasive imaging modality can be used instead of contrast venography in most patients to assess the presence and extent of vena caval tumor involvement by renal cell carcinoma. Contrast venography should be used for those patients with suspected cardiac involvement and for those whose tumor thrombus extent remains unclear after magnetic resonance imaging. (J. Urol., 138: 1220-1222, 1987)
The clinical staging of retroperitoneal tumors involving the inferior vena cava has been accomplished traditionally with radiological imaging techniques. For renal cell carcinoma arte- riographic imaging has been replaced in most cases by comput- erized tomography (CT). With both of these modalities the presence of inferior vena caval tumor involvement can be detected frequently but the actual extent of the thrombus usually is defined poorly. When this type of case is being staged preoperatively the resectability of the over-all tumor as well as the extent of the vena caval tumor thrombus should be known before a surgical approach can be planned or even considered.1
Extension of renal cell carcinoma into the vena cava is found in 4 to 10 per cent of the patients who undergo nephrectomy because of tumor.2,3 Wilms tumor and adrenocortical carcinoma rarely can extend intraluminally into the vena cava.4 Primary vena caval leiomyosarcomas also have been reported.5 It has been shown that the key to successful removal of intracaval tumor thrombi is the preoperative radiographic delineation of the extent of the thrombus.1 The superior extent of the tumor thrombus margin determines the operative approach. Cur- rently, the best modality to define the vena caval thrombus is contrast venography through a femoral vein approach. If the superior limit of the thrombus is not visualized owing to throm- bus obstruction of the vena cava then an additional contrast venographic study must be performed through a superior transatrial approach.
Recently magnetic resonance imaging (MRI) has become available at our institution. MRI was used in 5 patients with retroperitoneal tumors to evaluate the extension of tumor into the inferior vena cava following which the tumors were removed surgically. These cases and the images obtained with magnetic resonance are reviewed.
MATERIALS AND METHODS
There were 3 women and 2 men who had involvement of the inferior vena cava suspected by CT and who, subsequently, were evaluated by MRI. Surgical confirmation was available in
Accepted for publication April 21, 1987.
each case. MRI was performed on a 0.5 Tesla super conducting magnet (Picker Vistaview).
In all patients multislice coronal T1-weighted scans with echo time 26 msec. and repetition time 550 or 683 msec. were performed. In 4 patients coronal multislice T2-weighted images were obtained with echo time 100 msec., repetition time 2,000 msec. (3 patients), and echo time 100 msec., repetition time 2,100 msec. (1 patient). Additional scans in the axial plane were obtained when deemed necessary. The slice thickness was 10 mm. without an intervening gap. A 128 × 256 matrix was used with a pixel size of 3.1 × 1.6 mm. Noncardiac gated studies were obtained in each case. In 1 patient an additional cardiac gated study was performed.
The following grading system for inferior vena caval tumor involvement was used: level I-involvement of the inferior vena cava limited to the subhepatic portion, level II-intrahepatic portion of the inferior vena cava involved (no right atrial involvement) and level III-right atrial involvement.1
CASE REPORTS
Case 1. A 59-year-old man had gross hematuria with no other symptoms. Physical examination was unremarkable. An excre- tory urogram revealed a large left renal mass with calcification, which was confirmed by a CT scan. Exploration was done through a left flank incision. Radical nephrectomy was per- formed but a large tumor thrombus was encountered when the renal vein was transected. This tumor stump was oversewn and it was not removed.
The patient was transferred to our hospital for additional treatment. Retrospective review of the CT scan revealed a level I vena caval thrombus that was confirmed by MRI (fig. 1). Through a right thoracoabdominal incision retroperitoneal lymph node dissection and resection of the vena caval tumor thrombus were performed. The level I thrombus had been defined precisely by MRI.
Case 2. A 71-year-old obese woman was evaluated because of a 100-pound weight loss and massive bilateral lower extremity edema with an associated left upper quadrant abdominal mass.
A CT scan of the abdomen revealed a large left renal mass with a tumor thrombus extending into the vena cava. An inferior venacavogram showed complete obstruction of the vena cava. MRI documented a level II thrombus in the mid hepatic vena cava (fig. 2). This renal cell carcinoma with its thrombus was removed en bloc through a right thoracoabdominal T incision, confirming the findings of MRI.
Case 3. A 45-year-old woman was evaluated for persistent mild ankle edema. Physical examination revealed a right ab-
dominal mass. A CT scan showed the right renal mass with vena caval tumor thrombus extension. MRI was used to docu- ment the level of this thrombus at the diaphragm (fig. 3). A venacavogram was not performed. At exploration through a right thoracoabdominal incision a large right renal cell carci- noma with its level II vena caval thrombus was removed en bloc.
Case 4. A 72-year-old woman presented with dyspnea and a right upper quadrant abdominal mass. A CT scan demonstrated a large right suprarenal mass with extension into the vena cava. MRI showed a level II vena caval thrombus (fig. 4). A cardiac echogram and transatrial venacavogram showed right atrial involvement. At exploration through a right thoracoabdominal approach a large right adrenocortical carcinoma and tumor thrombus were removed. The intracaval tumor thrombus had a pedunculated extension into the right atrium (level III).
Case 5. A 57-year-old man had gross hematuria. History was significant for episodic congestive heart failure. Physical ex- amination revealed abdominal ascites, venous collaterals and massive lower extremity pitting edema. A CT scan showed a large right renal mass with a vena caval tumor thrombus. Without knowing the limits of the thrombus, exploration had been done elsewhere through a flank incision with the intention of performing radical nephrectomy. Large venous collaterals were encountered and tumor resection was not done.
The patient was transferred to the Kenneth Norris, Jr. Cancer Hospital and Research Institute for further treatment. MRI showed a level III thrombus extending into the right atrium (fig. 5). After 1 month of hyperalimentation and diuretic therapy, the renal cell carcinoma and thrombus were removed en bloc through a right thoracoabdominal incision, confirming the findings on MRI.
RESULTS
All 5 patients had tumor thrombus extending into the inferior vena cava: 4 had renal cell carcinoma and 1 had adrenocortical carcinoma. The thrombus level was I in 1 patient, II in 2 and III in 2. The extent of vena caval involvement predicted by MRI preoperatively was confirmed by the surgical findings in 4 patients. In case 4 MRI predicted level II involvement but 2- dimensional echocardiography demonstrated right atrial in- volvement. Surgically, level III invasion was present. This discrepancy may have been owing to the intermittent flipping of the tumor thrombus into the right atrium from the inferior vena cava. Cardiac gating was not available during MRI in this patient.
Compared to the normal liver, all 4 renal cell carcinomas were isointense on the T1-weighted images. T2-weighted im- ages were obtained in 3 patients with renal cell carcinoma with the tumor being hypointense compared to normal liver in 1 case, isointense in 1 and hyperintense in 1. When compared to the normal liver, the adrenocortical carcinoma was isointense on T1-weighted images and hypointense on the T2-weighted
A
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1
A
B
study. Inferior vena caval involvement by tumor was demon- strated on T2-weighted images in each case.
DISCUSSION
Since 4 to 10 per cent of the patients undergoing nephrectomy for renal cell carcinoma have inferior vena caval involvement and the operative approach depends on the extent of tumor involvement, it becomes imperative that the exact extent of tumor be delineated preoperatively. While the resolution of MRI is not as high as CT, MRI does define vena caval tumor thrombi better than CT.6-8 We have not found CT or MRI to be useful in separating intraluminal vena caval tumor throm- bosis from intraluminal tumor thrombosis with infiltration of the wall of the vena cava. In a recent series MRI was able to stage 96 per cent of renal cell carcinomas correctly.9 In 4 of our 5 patients MRI correlated well with the surgical findings. In the patient in ,whom MRI showed level II involvement the correct staging of the atrial involvement may have been possible if cardiac gating had been available.
The major advantage of MRI is that it can demonstrate readily the patency of major vessels, such as the inferior vena cava, without the administration of a contrast agent, since the signal from the blood flowing in vessels is much lower than that from tumor thrombus and, therefore, the tumor thrombus can be identified readily. MRI can acquire images directly in coronal, sagittal or axial planes. This ability to scan in the sagittal and coronal planes is an important advantage of MRI over CT scanning. Sagittal and coronal scans can aid in the delineation of the extent of the lesion. Although venacavogra- phy is excellent to demonstrate the extent of the thrombus, it is invasive and if there is complete obstruction of the inferior
vena cava a superior vena caval injection and perhaps a right atrial injection by a superior approach may become necessary, increasing patient discomfort, imaging time and exposure to additional iodinated contrast material. Abdominal ultrasound can be used to detect thrombotic extension into the vena cava when integrated with CT scanning.1º Older generation axial CT scans have not been reliable in determining the extent of intrahepatic vena caval thrombi.1 Current CT scanning per- formed for evaluation of inferior vena caval patency requires a meticulous technique with a fast scanner and can be done only in the axial plane.
Currently, we prefer CT scanning to define renal masses. If a vena caval tumor thrombus is suspected or cannot be ruled out by CT we prefer MRI to detect and to define the extent of the vena caval tumor thrombus. While our experience is limited, MRI has defined the extent of the vena caval tumor involve- ment more accurately than CT. While determining the accuracy of MRI in detecting vena caval tumor thrombi must await the statistical analysis of more experience, we are encouraged by these early results. We now use contrast venography only for those patients in whom right atrial tumor involvement is sus- pected or for those whose tumor thrombus extent remains unclear after MRI.
REFERENCES
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3. Skinner, D. G., Pfister, R. F. and Colvin, R .: Extension of renal cell carcinoma into the vena cava: the rationale for aggressive surgical management. J. Urol., 107: 711, 1972.
4. Skinner, D. G .: Unpublished data.
5. Bretan, P. N., Jr., Williams, P. D. and Hricak, H .: Preoperative assessment of retroperitoneal pathology by magnetic resonance imaging: primary leiomyosarcoma of inferior vena cava. Urology, 28: 251, 1986.
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8. Karstaedt, N., Mccullough, D. L., Wolfman, N. T. and Dyer, R. B .: Magnetic resonance imaging of the renal mass. J. Urol., 136: 566, 1986.
9. Hricak, H., Demas, B. E., Williams, R. D., McNamara, M. T., Hedgcock, M. W., Amparo, E. G. and Tanagho, E. A .: Magnetic resonance imaging in the diagnosis and staging of renal and perirenal neoplasms. Radiology, 154: 709, 1985.
10. Dal Bianco, M., Breda, G., Artibani, W., Bassi, P., Ricciardi, G., Marcon, M., De Faveri, D. and Pagano, F .: Echography in vena cava invasion from renal tumors. Eur. Urol., 11: 95, 1985.