Planning nephron-sparing renal surgery using 3D helical CT angiography

Perirenal fat invasion on renal cell carcinoma: evaluation with multidetector computed tomography-multivariate analysis

OBJECTIVE

The objective of this study was to assess the accuracy of multidetector computed tomography (CT) in diagnosing perinephric (PN) and/or renal sinus (RS) fat invasion in patients with renal cell carcinoma (RCC), with reference to the CT findings predictive for the diagnosis of invasion.

METHODS

This was a retrospective study of 48 RCCs. Examinations were performed on a 16-row CT scanner, including unenhanced and 3-phase contrast-enhanced CT scanning. Unenhanced transverse images and multiplanar reformations of each contrast-enhanced CT phase were evaluated. The predictive value of CT findings in diagnosing PN and/or RS fat invasion was determined using multivariate logistic regression analysis.

RESULTS

The CT findings that were most predictive for the diagnosis of PN fat invasion were the presence of contrast-enhancing nodules in the PN fat and tumoral margins. Invasion of the pelvicaliceal system was the most significant predictor in the diagnosis of RS fat invasion.

CONCLUSIONS

Multidetector CT provides satisfactory results in detecting PN and/or RS fat invasion in RCC.

Computed tomography dataset postprocessing: from data to knowledge

The introduction of spiral computed tomography from the days of single-slice spiral to today's 64-row multidetector computed tomography and beyond creates datasets with unprecedented spatial and temporal resolution. The key to computed tomography imaging in the big picture is not in the acquisition of data, but in the use of the data acquired. By supplementing traditional axial interpretation with 3-dimensional rendering of the computed tomography volume, the greatest amount of information available is extracted. The information provided by a comprehensive postprocessed study, which includes multiplanar reconstruction in the coronal, sagittal, and oblique plane, as well as 3-dimensional maps of both the arterial and venous phase datasets using volume rendering and maximum intensity projection techniques, allows for key clinical decisions to be made with a high degree of accuracy. Postprocessing of computed tomography data is thus no longer an option, but a true requirement in this era of 64-row multidetector computed tomography and beyond.

The utility of 64 channel multidetector CT angiography for evaluating the renal vascular anatomy and possible variations: a pictorial essay

The increased use of laparoscopic nephrectomy and nephron-sparing surgery has prompted the need for a more detailed radiological evaluation of the renal vascular anatomy. Multidetector CT angiography is a fast and accurate modality for assessing the precise anatomy of the renal vessels. In this pictorial review, we present the multidetector CT angiography appearances of the normal renal vascular anatomy and a spectrum of various anomalies that require accurate vascular depiction before undergoing surgical treatment.

Radiologic evaluation of small renal masses (I): pretreatment management

When characterizing a small renal mass (SRM), the main question to be answered is whether the mass represents a surgical or nonsurgical lesion or, in some cases, if followup studies are a reasonable option. Is this a task for a urologist or a radiologist? It is obvious that in the increasing clinical scenario where this decision has to be made, both specialists ought to work together. This paper will focus on the principles, indications, and limitations of ultrasound, CT, and MRI to characterize an SRM in 2008 with a detailed review of relevant literature. Special emphasis has been placed on aspects regarding the bidirectional information between radiologists and urologists needed to achieve the best radiological approach to an SRM.

Volume-rendered three-dimensional spiral computed tomographic angiography as a planning tool for microsurgical reconstruction in patients who have had operations or radiotherapy for oropharyngeal cancer

Three-dimensional spiral computed tomographic angiography (3D-SCTA) is a minimally invasive method of delineating vessels in three-dimensional detail. Our aim was to evaluate the clinical usefulness of volume-rendered three-dimensional SCTA for planning microsurgical reconstruction. Eighteen patients had a spiral computed tomogram (CT) of the extracranial carotid arteries. The volume rendering technique (VRT) was used to visualise the cervical vessels, and the three-dimensional SCTA images evaluated by a staff radiologist. Radiographic and operative findings were correlated in 13 of 18 patients. The anatomical and pathological alterations of vascular anatomy identified by three-dimensional SCTA correlated exactly with operative findings and led to a successful microsurgical reconstruction. Oropharyngeal reconstruction with microvascular free flaps requires accurate evaluation of the vascular system of the carotid arteries, and improves the accuracy of diagnostic decisions. Three-dimensional SCTA enables the surgeon to establish an appropriate treatment plan.

Visualization of intrarenal vessels by 3.0-T MR angiography in comparison with digital subtraction angiography using renal specimens

BACKGROUND

MRI at 3.0 T enables high-spatial resolution for renal MR angiography.

OBJECTIVE

Evaluation of an arterial tree model in animal kidney specimens with comparison of digital subtraction angiography (DSA) and high-field MRI to find out the maximum spatial resolution of intrarenal vessels. It was considered that objective quantitation of angiogram quality could be achieved.

MATERIALS AND METHODS

A total of 27 pig kidney specimens were examined by MR angiography (flash 3D) using a 3.0-T scanner (TRIO; Siemens, Erlangen, Germany) with an eight-channel head coil and a voxel size of 0.9x0.9x1.1 mm in the early arterial phase after implantation of a 4F catheter in the renal artery. DSA (Integris, Philips, Best, The Netherlands) was performed immediately after the MRI. With the help of semiautomated segmentation, all vessels were marked for comparison of the vessel trees. The Wilcoxon rank test was used for statistical evaluation of vessel numbers and branching depths.

RESULTS

Objective comparison between DSA and MR angiography was achieved. High-field MR angiography had the ability to depict vessels up to the seventh branching on average. Significant differences in vessel delineation and counts were found from the fifth level of intrarenal branching onwards with DSA showing an advantage.

CONCLUSION

High-field MRI has great potential in the detection of intrarenal arteries and is comparable to DSA in visualization of the central intrarenal vessel tree.

Comparison of 16-MDCT and MRI for Characterization of Kidney Lesions

OBJECTIVE

The objective of our study was to compare the diagnostic performance of 16-MDCT with that of MRI in the characterization of kidney lesions.

SUBJECTS AND METHODS

Twenty-eight patients with kidney lesions detected with sonography and requiring further evaluation were examined. MDCT was performed in the unenhanced, arterial, and portal venous phases. MRI was performed at 1.5 T with T2- and T1-weighted and dynamic gadolinium-enhanced sequences. Consensus reading was done by two radiologists. Image quality was rated on a four-point scale. Classification of lesions as surgical or nonsurgical was done with five levels of confidence, and it was required that a definite diagnosis be assigned to each lesion. The 1997 TNM classification was used for staging. Statistical analysis was done by receiver operating characteristic analysis or paired Student's t test. Histologic or follow-up findings at least 12 months after the primary diagnosis served as the standard of reference.

RESULTS

The image quality of MDCT (mean grade, 2.79 on a 0-3 scale) was superior to that of MRI (1.93; p < 0.01). The area under the curve for differentiating surgical from nonsurgical lesions was 0.979 for MDCT and 0.957 for MRI with resulting sensitivity and specificity values of 92.3% and 96.3% for MDCT and 92.3% and 91.3% for MRI. Sensitivity and specificity for definite classification of the lesions were 93.8% and 68.4% for MDCT and 93.8% and 71.4% for MRI.

CONCLUSION

Both MDCT and MRI are excellent for differentiating surgical from nonsurgical kidney lesions. Both methods have low specificity for the differentiation of benign from malignant lesions.

[New techniques in computed tomography. Significance for urology]

Computed tomographic (CT) imaging has become the modality of choice for the assessment of patients with urological malignancies. Recently, multi-slice CT imaging was introduced, providing faster acquisition times and higher resolution leading to improved image quality. Several studies show that thin-slice, high-resolution acquisition strategies lead to an improved accuracy for T-staging, especially of renal cell carcinomas. Three-dimensional post-processing techniques for the visualization of the vascular supply as well as the ureter (CT-angiography and CT-urography) are helpful for surgical planning. Compared to conventional imaging strategies unenhanced CT images render higher sensitivities and specificities for detecting stone disease in patients with acute flank pain. In the USA unenhanced CT imaging has almost replaced conventional urography, as no contrast agent is administered and the examination time is shorter. PET/CT examinations provide information on the morphology and function of tumors in one examination. However, there are only few data available for the assessment of urologic tumors.

Selective intra-arterial 3-dimensional computed tomography angiography for preoperative evaluation of nephron-sparing surgery

OBJECTIVE

To evaluate selective intra-arterial 3-dimensional computed tomography (3D-CT) angiography as a tool for the preoperative evaluation of nephron-sparing surgery (NSS).

METHODS

Twenty-three patients with renal cell carcinoma indicating NSS underwent selective intrarenal 3D-CT angiography. The time-lapse dual-phase technique was used for simultaneous vascular and urographic visualization. The 3D images were created by the shaded volume-rendering method. The CT attenuation of target structures was measured for quantitative evaluation. The 3D images were visually evaluated for the renal artery, vein, and collecting system using a grading system. Results were statistically analyzed.

RESULTS

The 3D-CT angiography depicted the intrarenal branches of the renal artery and vein and the whole collecting system in most patients. Visualization of the renal artery was significantly correlated to its CT attenuation. Visualization of the renal vein was correlated to its CT attenuation adjusted by the surrounding renal parenchyma.

CONCLUSION

Selective intra-arterial 3D-CT angiography allows the detailed visualization of intrarenal structures.

Diagnostic accuracy of staging renal cell carcinomas using multidetector-row computed tomography and magnetic resonance imaging: a prospective study with histopathologic correlation

OBJECTIVE

The aim of this prospective study is to compare the diagnostic accuracy of multidetector-row computed tomography (CT) and magnetic resonance imaging (MRI) in tumor staging of renal cell carcinomas.

METHODS

In a prospective study, 82 renal cell carcinomas were assessed for tumor staging before surgery using multidetector-row CT and MRI, the results of which were then correlated to histopathologic staging. Triphasic CT (noncontrast, arterial phase, and parenchymal phase) imaging was performed using multidetector-row CT with a reconstructed slice thickness of 2 mm. In MRI, a transverse T1-weighted gradient echo sequence with and without administration of Gd-DTPA, a transverse T2-weighted respiratory-gated turbo spin echo (TSE) sequence, and a coronal T1-weighted gradient echo sequence with Gd-DTPA were used. In addition, multiphasic 3-dimensional angiography after Gd-DTPA injection and a transverse T1-weighted fat-suppression sequence were performed.

RESULTS

With MRI, readers 1 and 2 correctly staged 71 and 64 tumors (overall accuracy of 0.87 and 0.78, respectively) and achieved Mantel-Haenszel chi(2) values of 66 and 63 (P < 0.0001). Computed tomography allowed correct staging of 68 and 66 tumors (readers 1 and 2, overall accuracy of 0.83 and 0.80, respectively) with Mantel-Haenszel chi(2) values of 54 and 54 for CT staging (P < 0.0001). No statistically significant difference between overall accuracy was found in the chi(2) test (P > 0.15).

CONCLUSION

Magnetic resonance imaging and multidetector-row CT with its multiplanar reconstruction capabilities achieve similar accuracy in tumor staging of renal cell carcinomas.

Comparison of Spatial Resolution in High-Resolution Multislice Computed Tomography and Digital Subtraction Angiography using Renal Specimens

OBJECTIVE

To compare maximum spatial resolution in multislice computed tomography (MS-CT) and digital subtraction angiography (DSA) using an arterial tree model for canine kidney specimens.

METHODS

Twenty-three isolated fox terrier kidneys were catheterized with a 4F catheter and underwent contrast-enhanced MS-CT with a maximum spatial resolution of 0.23-mm isotropic voxel size in an early arterial phase. In addition, a digital subtraction angiogram was performed on all kidneys. The kidneys were segmented semiautomatically, and each parenchymal vessel that was identified in the kidney was marked. The maximum intensity projections of arterial vessels in the CT datasets were evaluated in a comparison with the DSA datasets.

RESULTS

No significant difference in vessel delineation and count was found at any level up to the fourth level of intrarenal branching.

CONCLUSION

MS-CT has the potential of replacing DSA in the diagnosis of intrarenal arteries.

Emerging technologies in uroradiologic imaging

Advances in imaging technologies have readily been incorporated into the practice of urology and have led to important advances in patient care and outcomes. In the area of oncology, advances in radiologic imaging are improving the ability of the urologist to diagnose and monitor urologic malignancies. Some of these technologies include positron emission tomography (PET), intraoperative ultrasound (IUS), 3-dimensional computerized tomography (3D-CT), and magnetic resonance spectroscopy (MRS). We provide an overview of these four emerging imaging modalities and their potential applications and limitations in the diagnosis and management of urologic malignancy.

Current concepts in the diagnosis and management of renal cell carcinoma: role of multidetector ct and three-dimensional CT

Renal cell carcinoma is the most common primary tumor of the kidney, with more than 30,000 new cases diagnosed in the United States each year. With the widespread use of cross-sectional imaging, many tumors are detected incidentally. Single- and multidetector computed tomography (CT) have helped refine the diagnostic work-up of renal masses by allowing image acquisition in various phases of renal enhancement after intravenous administration of a single bolus of contrast material. The scanning protocol should include unenhanced CT followed by imaging during the corticomedullary and nephrographic phases of enhancement. The nephrographic phase is the most sensitive for tumoral detection, while the corticomedullary phase is essential for imaging the renal veins for possible tumoral extension and the parenchymal organs for potential metastases. Knowledge of the tumoral stage at the time of diagnosis is essential for prognosis and surgical planning. The accuracy of CT for staging has been reported to reach 91%, with most staging errors related to the diagnosis of perinephric extension of tumor. Three-dimensional CT provides the urologist with an interactive road map of the relationships among the tumor, the major vessels, and the collecting system. This information is particularly critical if the tumor extends into the inferior vena cava and if nephron-sparing surgery is being planned.

Role of computer technology in medical illustration

OBJECTIVE

Recent improvements of computer technology have resulted in a new approach to medical illustration and the scientific research process. The purpose of this manuscript is to define the current state of the art and to review paths of progress.

CONCLUSION

Using examples, we compared the process of time-intensive hand-rendered art with current art created using new computer technology. Specific emphasis was made on the newest technologies and how high-quality lower cost medical art can now be created. These newly available tools and illustration methods have resulted in a new approach to research, creation, and reproduction of medical art.