Assessment of the kidney tumor vascular supply by two-phase MDCT-angiography
Introduction
Malignant tumors of the kidneys account for only 1–2% of all malignancies. More than 90% of kidney malignancies are renal cell carcinoma (RCC), while urothelial carcinoma accounts for less than 10%. The incidence of RCC in the population reaches up to 20 new registered tumors per 100,000 population, the number increases slowly according to the incidental detection. Males are predominantly affected, with the male/female ratio ranging between 2:1 and 3:1. Three main subtypes of RCC have been identified: (1) conventional, clear cell, renal carcinoma (CRCC), (2) papillary renal cell carcinoma (PRCC), and (3) chromophobic renal cell carcinoma. The majority of RCC's are CRCC's (over 75%); about 15% are PRCC's, with about 5% being chromophobic RCC's [1], [2]. Current advanced surgical techniques, such as laparoscopic or retroperitoneoscopic nephrectomy and nephron-sparring resection are less invasive surgical procedures used in the treatment of renal tumors [3], [4]. Exact renal tumor staging is critical, as primary surgical resectability is the main condition of successful treatment [5], [6], [7]. Exact assessment of the vasculature of the kidney is essential for surgery planning [8]. Not only the number, site of origin and branching of the renal vessels but, also, the presence of neoplastic vascular invasion or parasitic vessels of the tumor have to be evaluated. The CT-angiography might be used instead obsolete dynamic conventional CT [9] (Fig. 1, Fig. 2, Fig. 3).
Computed tomography angiography (CTA) is well established as a non-invasive technique for imaging of the renal arteries and other visceral abdominal arteries [8], [9], [10], [11], [12], [13], [14], [15]. However, whereas the main renal arteries can be reliably displayed, imaging of the aberrant arteries and branching of the main arteries is not so frequently used as that of the stem arteries [16]. Similarly, two-phase computed tomography is well established in the evaluation of primary and secondary tumors of the liver [17], [18], two-phase examination in the arterial and venous phases is reported relatively rare in the kidneys [19], [20], [21]. Recent studies performed with the use of the multidetector-row CT (MDCT) yielded very high sensitivities and specificities in detecting renal artery stenoses or assessment of the transplant-donor kidney vasculature [12], [22], [23]. The vascular supply of the kidney with tumor can be more complicated due to the enlargement of the capsular or other aberrant vessels. Thus, reliable detection of the complete vascular supply remains a challenge for non-invasive imaging. The aims of the present study were to evaluate the accuracy of two-phase renal CTA in assessing the renal vascular topography and renal tumor staging as compared with surgical and pathological findings.
Section snippets
Subjects and methods
A total of 50 consecutive patients (mean age 58.6 years; range 43–82; 27 males, 23 females) referred for computed tomography due to a suspected tumor were enrolled in a prospective study. All patients were included in this study based only, on the ultrasound finding; no CT examination was done in the past. General informed consent with CTA examination was obtained by the referring physician.
All patients underwent two-phase CTA using a 16-detector-row scanner (Somatom Sensation 16, Siemens,
Results
The revealed advanced malignancy (unresectable tumor or multiple metastases—clinical stage IV) required that three patients be treated using only palliative therapy, nephrectomy was not performed. The remaining 47 patients underwent unilateral surgery within 1 week after CT-angiography and all their tumors were found resectable, procedures review showed in Table 1. A malignant renal tumor was confirmed in 44 cases, benign tumors in 3 cases (Table 2). Correct description and display of the renal
Discussion
Computed tomography angiography (CTA) is a valuable, minimally invasive imaging tool for the visualization and evaluation of the abdominal vessels [10], [11], [12], [14], [24]. Faster scanning ameliorates the contrast bolus exploitation and therefore decreases the overlaying opacification of the veins and arteries [18], [24]. Therefore, it seems to be advantageous to divide data acquisition into two phases, an arterial and a renal-venous one [18]. The high craniocaudal resolution makes it
Acknowledgement
Supported by the research project MSM 0021620819 of the Czech Government.
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