3-DIMENSIONAL VOLUME RENDERED COMPUTERIZED TOMOGRAPHY FOR PREOPERATIVE EVALUATION AND INTRAOPERATIVE TREATMENT OF PATIENTS UNDERGOING NEPHRON SPARING SURGERY

Laparoscopic Radical Nephrectomy

In addition to its established advantages, laparoscopic radical nephrectomy (RN) poses a unique set of challenges over traditional open surgery. In this study, we discuss preoperative considerations and detailed steps for laparoscopic RN. We review the transabdominal approach in detail, including patient positioning, equipment, and port placement in addition to the surgical steps. Intraoperative decisions such as adrenal management, renal preservation, and tumor identification are reviewed. Common complications of laparoscopic renal surgery are also summarized.

Three-dimensional printed model of bilateral Wilms tumor: A useful tool for planning nephron sparing surgery

Nephron sparing surgery (NSS) is increasingly utilized to treat patients with bilateral Wilms tumor. We present a case of NSS planning using a three-dimensional computerized and printed model of both kidneys with anatomical structures of interest (parenchyma, renal pelvis, major calyx, renal artery, renal vein, and tumor). This model allowed a better understanding of the anatomic relation between the tumor and the normal kidney on each side, improving the surgical planning and the preoperative discussion with the patient's family.

The value of three-dimensional helical computed tomography for the retrograde flexible ureteronephroscopy in the treatment of lower pole calyx stones

Objective

The aim of our study was to determine if there is any advantage of three-dimensional helical computed tomography (3D-HCT) over intravenous urogram (IVU) for the retrograde flexible ureteronephroscopy in the treatment of lower pole calyx stones.

Methods

From June 2012 to January 2014, a total of 52 cases of lower pole renal stones underwent retrograde intrarenal surgery (RIRS) in our center. All patients underwent a preoperative IVU and three-dimensional helical computed tomography urography (3D-CTU) program to define the collecting system anatomy, manly concerning the following lower pole features; infundibu-lopelvic angle (IPA), infundibular length (IL), and infundibular width (IW). The examinations were performed in the same center of reference with a standardized method and with 3D-HCT Siemens Somaton Plus equipment. The measurements were performed by the same researcher, using a ruler and a square.

Results

Based on clinical threshold difference of the anatomic factors on an IVU image to compare the difference between an IVU image and a 3D-CT image of 52 patients, the IPA was <30° when measured on intravenous pyelography (IVP) for 21 patients. We found that with the IPA of <30° measured with IVP only 19% (4/21) were correctly classified in the same size category using 3D-HCT, whereas 81% (17/21) were upgraded to 40–50° on 3D-CT. This difference was significant between IVP and 3D-HCT.

Conclusions

3D-HCT has advantages over IVU when analyzing the morphometric and the morphological features of kidney lower pole spatial anatomy for the retrograde flexible ureteronephroscopy in the treatment of lower pole calyx stones.

A Literature Review of Renal Surgical Anatomy and Surgical Strategies for Partial Nephrectomy

CONTEXT

A detailed understanding of renal surgical anatomy is necessary to optimize preoperative planning and operative technique and provide a basis for improved outcomes.

OBJECTIVE

To evaluate the literature regarding pertinent surgical anatomy of the kidney and related structures, nephrometry scoring systems, and current surgical strategies for partial nephrectomy (PN).

EVIDENCE ACQUISITION

A literature review was conducted.

EVIDENCE SYNTHESIS

Surgical renal anatomy fundamentally impacts PN surgery. The renal artery divides into anterior and posterior divisions, from which approximately five segmental terminal arteries originate. The renal veins are not terminal. Variations in the vascular and lymphatic channels are common; thus, concurrent lymphadenectomy is not routinely indicated during PN for cT1 renal masses in the setting of clinically negative lymph nodes. Renal-protocol contrast-enhanced computed tomography or magnetic resonance imaging is used for standard imaging. Anatomy-based nephrometry scoring systems allow standardized academic reporting of tumor characteristics and predict PN outcomes (complications, remnant function, possibly histology). Anatomy-based novel surgical approaches may reduce ischemic time during PN; these include early unclamping, segmental clamping, tumor-specific clamping (zero ischemia), and unclamped PN. Cancer cure after PN relies on complete resection, which can be achieved by thin margins. Post-PN renal function is impacted by kidney quality, remnant quantity, and ischemia type and duration.

CONCLUSIONS

Surgical renal anatomy underpins imaging, nephrometry scoring systems, and vascular control techniques that reduce global renal ischemia and may impact post-PN function. A contemporary ideal PN excises the tumor with a thin negative margin, delicately secures the tumor bed to maximize vascularized remnant parenchyma, and minimizes global ischemia to the renal remnant with minimal complications.

PATIENT SUMMARY

In this report we review renal surgical anatomy. Renal mass imaging allows detailed delineation of the anatomy and vasculature and permits nephrometry scoring, and thus precise, patient-specific surgical planning. Novel off-clamp techniques have been developed that may lead to improved outcomes.

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.

Application of a vasculature model and standardization of the renal hilar approach in laparoscopic partial nephrectomy for precise segmental artery clamping

BACKGROUND

Clamping the segmental renal artery instead of the main renal artery during nephron-sparing surgery is a promising technique to decrease warm ischemia injury. Understanding vasculature characteristics and adopting an appropriate hilar approach to segmental arteries are essential to the technique.

OBJECTIVE

To study the role of the vasculature model and to standardize the renal hilar approach in segmental renal artery dissection during laparoscopic partial nephrectomy (LPN).

DESIGN, SETTING, AND PARTICIPANTS

A retrospective analysis of a consecutive series of 82 patients who underwent LPN with a precise clamping technique from December 2009 to June 2011 with a mean follow-up of 20 mo.

SURGICAL PROCEDURE

Three-dimensional dynamic renal vascular models were established based on dual-source computed tomographic angiography. Clamping number, clamping position, and a different hilar approach accessing target segmental arteries were determined preoperatively. Target arteries were dissected and clamped based on the model. Tumor excision and renorrhaphy were performed under regional parenchymal ischemia.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Renal vascular characteristics and surgical outcomes were analyzed. The outcomes among different surgical approaches were compared using one-way analysis of variance test or Fisher exact test.

RESULTS AND LIMITATIONS

All surgeries were performed successfully without converting to main renal artery clamping or radical nephrectomy. The median operative time was 90 min, and the mean clamping time was 24 min. The median estimated blood loss (EBL) was 200 ml, and six patients received blood transfusions. Five patients had hematuria without any intervention. One patient had a postoperative hemorrhage and received selective embolization intervention. Statistical analysis showed that appropriate surgical approaches chosen from the models led to comparable operative times, EBL, and complication rates. The limitation of the study lies on its retrospective feature.

CONCLUSIONS

A renal vasculature model provides effective orientation for a precise clamping technique. A standardized hilar approach based on the model optimizes the surgical procedure and leads to satisfactory surgical outcomes.

Precise segmental renal artery clamping under the guidance of dual-source computed tomography angiography during laparoscopic partial nephrectomy

BACKGROUND

Minimizing warm ischemic (WI) injury is one technical focus of partial nephrectomy (PN). Inducing regional ischemia in the tumor area by clamping segmental renal arteries has become an alternative method to decrease WI injury.

OBJECTIVE

To study the technical feasibility of precise segmental artery clamping under the guidance of dual-source computed tomography (DSCT) angiography during laparoscopic partial nephrectomy (LPN) and to analyze the factors affecting surgical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective analysis of 125 patients with unilateral kidney tumor treated from December 2009 to November 2011 with a mean follow-up of 18 mo.

INTERVENTION

All patients received retroperitoneal LPN with the feeding segmental arteries precisely clamped. Most of the target branches were dissected close to the hilar parenchyma. The tumor was excised after precise clamping and renorrhaphy was performed.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Univariable and multivariable logistic regression analyses were performed for categorical variables, and continuous variables were analyzed by linear regression.

RESULTS AND LIMITATIONS

The target branches were isolated and clamped successfully in all patients without clamping the main renal artery. Median estimated blood loss (EBL) was 200 ml, and nine patients received blood transfusion. The accuracy of feeding artery orientation by DSCT angiography reached 93.6%. Tumor size, location, and growth pattern independently influenced the number of clamped branches. The number of clamped branches was significantly associated with postoperative renal function and EBL. Limitations of this study include its retrospective nature and that data are from a single-surgeon series.

CONCLUSIONS

The precise segmental artery clamping technique under the guidance of DSCT angiography is feasible and efficient to excise the tumor and to protect the normal parenchyma. The number of clamped branches is associated with tumor characteristics and can predict EBL and loss of renal function.

Advancements in laparoscopic partial nephrectomy: expanding the feasibility of nephron-sparing

Partial nephrectomy (PN) offers equivalent oncologic outcomes to radical nephrectomy (RN) but has greater preservation of renal function and less risk of chronic kidney disease and cardiovascular disease. Laparoscopic PN remains underutilized likely because it is a technically challenging operation with higher rates of perioperative complications compared to open PN and laparoscopic RN. A review of the latest PN literature demonstrates that recent advancements in laparoscopic approaches, imaging modalities, ischemic mitigating strategies, renorrhaphy techniques, and hemostatic agents will likely allow greater utilization of LPN and expand its usage to increasingly more complex tumors.

Value of multidetector computed tomography image segmentation for preoperative planning in general surgery

BACKGROUND

Using practical examples, this report aims to highlight the clinical value of patient-specific three-dimensional (3D) models, obtained segmenting multidetector computed tomography (MDCT) images, for preoperative planning in general surgery.

METHODS

In this study, segmentation and 3D model generation were performed using a semiautomatic tool developed in the authors' laboratory. Their segmentation procedure is based on the neighborhood connected region-growing algorithm that, appropriately parameterized for the anatomy of interest and combined with the optimal segmentation sequence, generates good-quality 3D images coupled with facility of use. Using a touch screen monitor, manual refining can be added to segment structures unsuitable for automatic reconstruction. Three-dimensional models of 10 candidates for major general surgery procedures were presented to the operating surgeons for evaluation. A questionnaire then was administered after surgery to assess the perceived added value of the new technology.

RESULTS

The questionnaire results were very positive. The authors recorded the diffuse opinion that planning the procedure using a segmented data set allows the surgeon to plan critical interventions with better awareness of the specific patient anatomy and consequently facilitates choosing the best surgical approach.

CONCLUSIONS

The benefit shown in this report supports a wider use of segmentation software in clinical practice, even taking into account the extra time and effort required to learn and use these systems.

Developments in kidney tumor nephrometry

With the widespread use of computed tomography imaging, the majority of renal tumors are currently detected incidentally at lower grade and stage. Partial nephrectomy has become the preferred treatment for many of these smaller, lower-stage, organ-confined tumors. Compared with radical nephrectomy, partial nephrectomy is more technically difficult to perform. Specific tumor features such as tumor size, depth, location, and proximity to the kidney vasculature and urinary collecting system affect the difficulty of resection. Classically, feasibility of resection has been determined subjectively. Recently, 3 methodologies have been proposed to provide standard, more objective preoperative assessment of tumor anatomy. These "nephrometry" systems include the R.E.N.A.L., PADUA, and C-index systems. In this article, we review aspects of each of these systems, their similarities and differences, and their relevance to clinical practice and academic reporting.

Single minimum incision endoscopic radical nephrectomy for renal tumors with preoperative virtual navigation using 3D-CT volume-rendering

Background

Single minimum incision endoscopic surgery (MIES) involves the use of a flexible high-definition laparoscope to facilitate open surgery. We reviewed our method of radical nephrectomy for renal tumors, which is single MIES combined with preoperative virtual surgery employing three-dimensional CT images reconstructed by the volume rendering method (3D-CT images) in order to safely and appropriately approach the renal hilar vessels. We also assessed the usefulness of 3D-CT images.

Methods

Radical nephrectomy was done by single MIES via the translumbar approach in 80 consecutive patients. We performed the initial 20 MIES nephrectomies without preoperative 3D-CT images and the subsequent 60 MIES nephrectomies with preoperative 3D-CT images for evaluation of the renal hilar vessels and the relation of each tumor to the surrounding structures. On the basis of the 3D information, preoperative virtual surgery was performed with a computer.

Results

Single MIES nephrectomy was successful in all patients. In the 60 patients who underwent 3D-CT, the number of renal arteries and veins corresponded exactly with the preoperative 3D-CT data (100% sensitivity and 100% specificity). These 60 nephrectomies were completed with a shorter operating time and smaller blood loss than the initial 20 nephrectomies.

Conclusions

Single MIES radical nephrectomy combined with 3D-CT and virtual surgery achieved a shorter operating time and less blood loss, possibly due to safer and easier handling of the renal hilar vessels.

Renal masses herniating into the hilum: technical considerations of the "ball-valve phenomenon" during nephron-sparing surgery

OBJECTIVES

To describe our technique to recognize and resect renal tumors "ball-valving" into the sinus. Partial nephrectomy (PN) offers a functional advantage over radical nephrectomy for many cases of localized renal cell carcinoma. However, PN is underutilized particularly in anatomically challenging cases. Often unrecognized is the tendency for central renal tumors to herniate into the renal sinus.

METHODS

From our prospective kidney cancer database, we identified 36 patients who underwent open, laparoscopic, or robotic PN for solitary localized renal cell carcinoma herniating into the renal sinus.

RESULTS

Axial and reformatted radiographs were reviewed for all renal hilar lesions. Intraoperative techniques include hilar dissection, establishment of a sinus plane allowing tumor and parenchymal retraction, reduction of the tumor out of the sinus, resection, and repair. Mean preoperative lesion size was 3.8 cm. Indications for PN included 15 of 36 (42%) absolute, 13 of 36 (36%) relative, and 2 of 36 (6%) reoperative PN. No procedure was converted to radical nephrectomy. Of the 36 PN, 5 (14%) were performed using a minimally invasive approach and no minimally invasive surgery procedures were converted to open. No patient required renal replacement.

CONCLUSIONS

Recognition of the tendency for hilar masses to herniate or "ball-valve" into the renal sinus is essential for effective PN of central tumors. By using our technique, we have demonstrated success in nephron-sparing surgery with minimal intraoperative complications and favorable postoperative outcomes in patients with central tumors herniating into the renal sinus.

Diagnostic accuracy of a volume-rendered computed tomography movie and other computed tomography-based imaging methods in assessment of renal vascular anatomy for laparoscopic donor nephrectomy

To evaluate the diagnostic accuracy of computed tomography (CT)-based imaging methods for assessing renal vascular anatomy, imaging studies, including standard axial CT, three-dimensional volume-rendered CT (3DVR-CT), and a 3DVR-CT movie, were performed on 30 patients who underwent laparoscopic donor nephrectomy (10 right side, 20 left side) for predicting the location of the renal arteries and renal, adrenal, gonadal, and lumbar veins. These findings were compared with videos obtained during the operation. Two of 37 renal arteries observed intraoperatively were missed by standard axial CT and 3DVR-CT, whereas all arteries were identified by the 3DVR-CT movie. Two of 36 renal veins were missed by standard axial CT and 3DVR-CT, whereas 1 was missed by the 3DVR-CT movie. In 20 left renal hilar anatomical structures, 20 adrenal, 20 gonadal, and 22 lumbar veins were observed during the operation. Preoperatively, the standard axial CT, 3DVR-CT, and 3DVR-CT movie detected 11, 19, and 20 adrenal veins; 13, 14, and 19 gonadal veins; and 6, 11, and 15 lumbar veins, respectively. Overall, of 135 renal vascular structures, the standard axial CT, 3DVR-CT, and 3DVR-CT movie accurately detected 99 (73.3%), 113 (83.7%), and 126 (93.3%) vessels, respectively, which indicated that the 3DVR-CT movie demonstrated a significantly higher detection rate than other CT-based imaging methods (P < 0.05). The 3DVR-CT movie accurately provides essential information about the renal vascular anatomy before laparoscopic donor nephrectomy.

[Laparoscopic nephrectomy in a living donor]

Kidney transplantation is the therapeutic option of choice for patients with end-stage renal disease. With the advent of safer harvesting techniques and immunosuppression, both donor and recipient outcomes have markedly improved in recent years. Kidney donation from Living donors remains the single most important factor responsible for improving patient and graft survival. The laparoscopic donor nephrectomy has revolutionized renal transplantation, allowing expansion of the donor pool by diminishing surgical morbidity while maintaining equivalent recipient outcome. This technique is now becoming the gold-standard harvesting procedure in transplant centres worldwide, despite its technical challenge and ongoing procedural maturation, especially early in the learning curve. Previous contraindications to laparoscopic donor nephrectomy are no longer absolute. In the following analysis, the procedural aspects of the laparoscopic donor nephrectomy are detailed including pre-operative assessment, operative technique and a review of the current literature delineating aspects of both donor and recipient morbidity and mortality compared with open harvesting techniques.

Volume rendering versus maximum intensity projection in CT angiography: what works best, when, and why

The introduction and widespread availability of 16-section multi-detector row computed tomographic (CT) technology and, more recently, 64-section scanners, has greatly advanced the role of CT angiography in clinical practice. CT angiography has become a key component of state-of-the-art imaging, with applications ranging from oncology (eg, staging of pancreatic or renal cancer) to classic vascular imaging (eg, evaluation of aortic aneurysms and renal artery stenoses) as well as newer techniques such as coronary artery imaging and peripheral runoff studies. With an average of 400-1000 images in each volume data set, three-dimensional postprocessing is crucial to volume visualization. Radiologists now have workstations that provide capabilities for evaluation of these data sets by using a range of software programs and processing tools. Although different systems have unique capabilities and functionality, all provide the options of volume rendering and maximum intensity projection for image display and analysis. These two postprocessing techniques have different advantages and disadvantages when used in clinical practice, and it is important that radiologists understand when and how each technique should be used.

Maximizing clinical information obtained by CT

CT scanning is an integral part of the urologist's practice today. It is the most commonly used imaging modality and the one with which urologists are most familiar. CT urography, CT angiography, and 3D reconstruction enable the urologist to perform comprehensive evaluations of patients who have different urologic diseases, using a single imaging modality. It is thus prudent that urologists become familiar with CT applications, to maximize the clinical information available from them.

The natural history of observed enhancing renal masses: meta-analysis and review of the world literature

PURPOSE

Standard therapy for an enhancing renal mass is surgical. However, operative treatment may not be plausible in all clinical circumstances. Data on the natural history of untreated enhancing renal lesions is limited but could serve as a decision making resource for patients and physicians. We examined available data on the natural history of observed solid renal masses.

MATERIALS AND METHODS

A Medline review of the literature was performed from 1966 to the present regarding untreated, observed, localized solid renal masses. To these data we added our institutional experience with a total of 61 lesions observed in 49 patients for a minimum of 1 year. Variables examined were initial lesion size at presentation, growth rate, duration of followup, pathological findings and progression to metastatic disease. Overall weighted mean estimates were calculated for lesion size at presentation, growth rate and followup based upon combining single institutional series with complete information.

RESULTS

We identified 10 reports from 9 single institutional series in the world literature regarding the natural history of untreated solid localized renal lesions. The series included 6 to 40 patients (mean 25) with a mean followup of 30 months (range 25 to 39). When combined with our institutional data, a total of 286 lesions were analyzed, of which 234 could be included in the meta-analysis. Mean lesion size at presentation was 2.60 cm (median 2.48, range 1.73 to 4.08). Meta-analysis revealed a mean growth rate of 0.28 cm yearly (median 0.28, range 0.09 to 0.86) at a mean followup of 34 months (median 32, range 26 to 39) in all series combined. Pathological confirmation was available in 46% of the cases (131 of 286) and it confirmed 92% (120 of 131) as RCC variants. Evaluable data in this subset of confirmed RCC demonstrated a mean growth rate of 0.40 cm yearly (median 0.35, range 0.42 to 1.6). Lesion size at presentation did not predict the overall growth rate (p = 0.46). Progression to metastatic disease was identified in only 1% of lesions (3 of 286) during followup.

CONCLUSIONS

The majority of small enhancing renal masses grow at a slow rate when observed. Although metastatic and cancer specific death are low, serial radiographic data alone are insufficient to predict the true natural history of these lesions. Therefore, physicians and patients assume a calculated risk when following these tumors. Basic biological data are needed to assess the natural history of untreated renal masses.

Long-term outcomes of the surgical management of renal cell carcinoma

It has been 35 years since the radical nephrectomy was standardized by the work of Robson et al. (J Urol 101:297-301, 1969). Despite being based on a retrospective review of only 88 cases operated upon over a span of 15 years, this publication was an important milestone in the attempt to create uniformity in the staging of Renal cell carcinoma (RCC), and the measurement of surgical outcomes for RCC. Although this manuscript forms the basis for our contemporary measurement of the long-term results of RCC surgery and set the standard to which the entire subsequent literature was compared, contemporary research subsequently has questioned many of Robson's conclusions regarding RCC. In Robson's era, the majority of patients presented with large, symptomatic tumors, pre-operative staging was imprecise, and many patients had locally advanced disease at the time of surgery: of the 88 patients in Robson's series, 75% were managed through a thoracoabdominal incision. Since that time, advances in renal imaging and clinical staging have led to the increased detection of incidental, lower stage, organ-confined tumors more amendable to expanded surgical options. Surgical techniques have evolved and technological advances have made possible new methods of managing renal tumors in situ that have emphasized a transition from radical to less extirpative approaches. In addition, understanding of the basic biology and genetics of kidney cancer has led to improved prognostication and the development of effective immunotherapies for advanced disease. The current concepts and long-term outcomes of the surgical management of RCC will be reviewed to help elucidate some of these changes, from the evolution of open to laparoscopic to percutaneous, from radical to partial to ablative approaches.

3-Dimensional computerized tomography in follow-up of patients with urinary diversion

INTRODUCTION

The aim of our study was to evaluate the usefulness of 3-dimensional computerized tomography (3D-CT) in routine follow-up of patients who had undergone radical cystectomy and different kinds of urinary diversions and compare it with conventional CT.

PATIENTS AND METHODS

Nineteen patients (18 men, 1 woman) who had undergone radical cystectomy and different kinds of urinary diversions with diagnosis of invasive bladder cancer were enrolled into the study. The mean age of the patients was 55.5 (46-69) years. For all patients, conventional CT was performed, followed by 3D reconstruction of these images.

RESULTS

Orthotopic ileal neobladder (Abol-Enein and Ghoneim procedure) was performed in 12, rectosigmoid pouch (Mainz pouch II) in 2 and ileal conduit in 5 patients. There were no pathological findings visible either on conventional CT or on 3D-CT, but the shape, configuration, and the relationships of the pouch with ureters, urethra and other adjacent organs were much better visualized on 3D-CT.

CONCLUSION

3D-CT did not have any advantages over conventional CT for showing pathological findings that were oncological origin, but as the anatomy of the lower urinary tract can be perfectly demonstrated, we think that it may be used for planning of a re-operation after urinary diversion and may help the urologist who has less experience with radiological studies to evaluate pouch configuration and indentations to the adjacent organs better.

Kidney displacement simulator for retroperitoneal laparoscopic nephrectomy

PURPOSE

We evaluated the efficacy of a renal displacement simulator originally developed at our department for retroperitoneal laparoscopic nephrectomy.

MATERIALS AND METHODS

A total of 12 patients with a malignant localized renal (7) or ureteral (5) neoplasm underwent multidetector row computerized tomography. Imaging data were sent to a dedicated work station to create volume rendering and virtual laparoscopic images of the kidney, which was displaced ventral using a retroperitoneal balloon. These findings were compared with video images obtained during laparoscopy surgery.

RESULTS

The kidney displacement simulator depicted all renal arteries (100% sensitivity) and 13 of 14 renal veins (93% sensitivity). Hilar anatomy, including the tumor, as well as major vessels and their relationships were visualized by the simulator in the laparoscopic views. The major vessel portions completely corresponded to those seen during surgery, and the left adrenal and gonadal veins were also synchronized quite well.

CONCLUSIONS

Our kidney displacement simulator was able to visualize the major vessel portions and branched small vessels, such as the adrenal and gonadal veins, prior to surgery. It is considered useful for providing guidance to surgeons and decreasing operative risks and possible complications.

Lessons learned in the surgical management of renal cell carcinoma

Surgical excision, the mainstay of management of renal cell carcinoma (RCC), has evolved significantly over the last 4 decades. Radiological imaging is crucial to the diagnosis and staging of RCC, and technological advances have facilitated more precise preoperative assessment. Additionally, wider use of cross-sectional imaging modalities has led to increasing incidental diagnosis of small, early-stage RCC. Nephron-sparing surgery (NSS), originally developed to treat RCC arising in a solitary functioning kidney, has been demonstrated to be a safe and effective alternative to radical nephrectomy. NSS is now also applicable to tumors of suitable size and anatomy in patients with a normal contralateral kidney, thus facilitating preservation of renal function and management of metachronous contralateral pathology. Laparoscopic and percutaneous approaches have developed over the last decade, thus providing minimally invasive modalities, with shortened convalescence and improved cosmesis. Advanced RCC, involving venous extension or nodal spread, is increasingly amenable to surgical management, although appropriate patient selection is crucial. Furthermore, surgical excision of the primary lesion appears to be an integral part of systemic therapy for metastatic RCC.

Multidetektorcomputertomographie (MDCT) der Nieren

Multidetector computed tomography (MDCT) possesses distinct advantages for examination of the kidneys. It carries the potential of becoming the gold standard of diagnostic work-up and surgical planning for most renal diseases and replacing conventional methods such as i.v. urography and angiography. The most outstanding improvements, in comparison to single slice spiral CT, are the speedier image acquisition and enhanced z-axis resolution, which aids particularly in visualization of the urinary tract as it aligns along the axis of the body. Respiratory artifacts are few or nonexistent even in patients who cannot hold their breath. This overview presents a strategy for prudent management of MDCT examinations and describes examination of the most important and frequent renal diseases using MDCT.

Design of functional simulation of renal cancer in virtual reality environments

OBJECTIVES

The preoperative planning of partial nephrectomy can be facilitated by the ability to view the tumor and surrounding tissue in three-dimensional (3D) virtual reality (VR). A technique to convert Digital Imaging and Communications in Medicine computed tomography scan data into a fully 3D VR environment was developed. The model can be transferred to a personal computer, allowing the surgeon to view the 3D model in the operating room.

METHODS

Computed tomography data from a patient with multifocal renal masses was converted into a 3D polygonal mesh using Amira running on a desktop personal computer with Windows XP Professional. A Silicon Graphics Monster Onyx2 running the Linux operating system was used to view the 3D stereo model in the VR environments: either the CAVE or a specialized desk called the Immersadesk. An application to view and interact with the model on a desktop personal computer was written in C++.

RESULTS

A 3D model of the kidney, the multiple tumors, and the associated systems was created. The model could be viewed and manipulated in a true VR environment and on a desktop personal computer.

CONCLUSIONS

This project completed two major goals. First, a 3D model of a kidney containing multiple masses was created and viewed in a VR environment. Second, an interface to display the model on a desktop personal computer in the operating room was created. This is the first step in bringing VR technology to the operating room to assist the surgeon directly.

Preoperative renal tumor evaluation by three-dimensional magnetic resonance imaging: Staging and detection of multifocality

OBJECTIVES

To evaluate, retrospectively, the staging accuracy of three-dimensional magnetic resonance imaging (3D-MRI) in our institution as a prelude to a prospective comparison of 3D-MRI and 3D computed tomography (CT) for preoperative planning of partial nephrectomy. In recent years, the use of 3D-CT for preoperative evaluation and surgical planning in patients undergoing nephron-sparing surgery has gained considerable popularity.

METHODS

The images of 26 consecutive patients evaluated by 3D-MRI as part of the preoperative imaging studies for renal tumor were evaluated retrospectively and compared with the surgical pathologic findings to evaluate the ability of 3D-MRI to predict tumor multifocality, tumor stage, collecting system invasion, and venous invasion.

RESULTS

3D-MRI accurately predicted tumor multifocality in 1 of 2 cases. Imaging identified five of seven multifocal lesions. Two subcentimeter lesions were missed. Preoperative staging was correct in 29 of 30 lesions (97% accuracy). One T3b tumor was incorrectly staged as T2. Venous invasion was identified in 2 of 3 cases (67% sensitivity), but no false-positive results were seen. 3D-MRI had 100% sensitivity and 88% specificity in the prediction of collecting system invasion.

CONCLUSIONS

The staging accuracy of 3D-MRI appears to be quite good. Given the accuracy of this technique, along with the popularity of 3D imaging before renal surgery, these results provide the impetus for a future study directly comparing 3D-CT with 3D-MRI in the capacity of surgical preoperative planning.

Laparoscopic and Partial Nephrectomy: Table 1

Radical nephrectomy is the gold standard curative operation for patients with localized renal cell carcinoma (RCC). Since its introduction in 1990, laparoscopic radical nephrectomy is being increasingly done at numerous institutions worldwide. In the hands of experienced laparoscopic urological surgeons and with adherence to established principles of open radical nephrectomy, laparoscopic radical nephrectomy is now a standard of care for patients with T1-3a N0 M0 RCC. Intermediate-term outcome data indicate equivalent cancer-free survival to open radical nephrectomy in such cases. Nephron-sparing surgery (NSS) is now an established approach for patients with localized RCC when there is a clinically relevant need to preserve renal function. NSS is also indicated in patients with a single, small, unilateral, localized RCC when the opposite kidney is completely normal. The technical success rate with NSS for RCC is excellent, and long-term patient survival free of cancer is comparable with that obtained after radical nephrectomy. We recently reviewed the results of NSS in 107 patients with localized sporadic RCC treated at the Cleveland Clinic before 1988 who were followed up for a minimum of 10 years. Long-term preservation of renal function was achieved in 93% of patients, and the 10-year cancer specific survival rate was 73%. Although open surgical partial nephrectomy remains the gold standard for nephron-sparing treatment of RCC, laparoscopic partial nephrectomy is now available in selected cases. The optimal indications for laparoscopic NSS are in patients with a relatively small and peripheral renal tumor. In such cases, laparoscopic NSS is proving to be an effective, minimally invasive therapeutic approach with respect to renal functional outcome, with additional advantages of reduced postoperative narcotic use, earlier hospital discharge, and a faster convalescence. The laparoscopic approach is associated with longer warm renal ischemia time, more major intraoperative complications, and more postoperative urological complications. Continued efforts are required to develop laparoscopic renal hypothermia techniques and to facilitate intrarenal suturing while minimizing the warm ischemia time.

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.

Renal imaging: what the urologist wants to know

Preoperative imaging in renal surgery is of utmost importance in contemporary surgical practice. From a diagnostic standpoint, imaging discovers many renal tumors incidentally before they become symptomatic. These tumors often are amenable to partial renal resection or minimally invasive surgical approaches. In general, surgical interventions for renal abnormalities have evolved to a less invasive endourologic or laparoscopic approach. Selection of the appropriate surgical intervention for renal tumors, collecting system tumors, and hydronephrosis depends heavily on the anatomy of the renal pathology. Thus, renal imaging is crucial in clinical decision-making. This article reviews the contribution of imaging to the surgical management of renal tumors, upper tract urothelial tumors, and ureteropelvic junction obstruction.

Evaluation of Small (≤ 3 cm) Renal Masses with MDCT:Benefits of Thin Overlapping Reconstructions

OBJECTIVE

Our purpose was to determine whether thin overlapping reconstructions using MDCT improve the detection and characterization of small renal masses.

MATERIALS AND METHODS

Thirty-seven patients were scanned with MDCT using 2.5-mm collimation. Nephrographic phase data were reconstructed in two ways: a standard protocol (5-mm section thickness, no overlap) and an experimental protocol (3-mm section thickness, 50% overlap). Masses were detected and classified into three groups: group 1, measuring less than 20 H on both protocols (classified as cysts on both); group 2, measuring 20 H or greater on standard protocol and less than 20 H on experimental protocol (classified as cysts using experimental protocol only); and group 3, measuring 20 H or greater on both protocols (not classified as cysts using either protocol). Masses 10 mm or larger in group 3 were evaluated further for enhancement. Statistically significant differences between protocols were assessed using an analysis of counts and proportions.

RESULTS

Of 175 detected lesions, 29 (17%) were detected only with the experimental protocol; all but one were smaller than 5 mm. Using the experimental protocol, of 45 masses between 5 and 10 mm, the number of masses that could be characterized as cysts increased from 13 (29%) to 38 (84%). The overall number of indeterminate lesions was reduced from 101 (69%) of 146 lesions detected with the standard protocol to 86 (53%) of 161 lesions detected with the experimental protocol.

CONCLUSION

Using MDCT and thin overlapping reconstructions, renal cysts as small as 5 mm can be diagnosed with more confidence than is possible with standard reconstructions, and the overall number of indeterminate renal masses is reduced.

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.

Three-dimensional Volume-rendered Helical CT before Laparoscopic Adrenalectomy

Use of three-dimensional (3D) volume-rendered helical computed tomography (CT) in surgical planning before laparoscopic adrenalectomy was evaluated in a retrospective study. In 35 consecutive patients before laparoscopic adrenalectomy, 3D volume-rendered CT scans were created from helical CT scans. Videotapes that showed anterior, lateral, posterior, and posterocephalic approaches were assessed retrospectively. The relationship (not contacting, abutting, displacing, or invading) of adrenal masses to adjacent organs (diaphragm, liver, spleen, kidneys, stomach, pancreas, and vessels) was recorded and compared with findings in surgery reports. When such findings were available, they corresponded to those in the videotape. Three-dimensional volume-rendered CT successfully displayed the relationship of adrenal masses to adjacent anatomic structures and organs before laparoscopic adrenalectomy.

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.

Three-dimensional image reconstruction for preplanning of renal surgery

Three-dimensional volume rendering has been performed in more than 200 patients undergoing nephron-sparing surgery at the authors' center. This technique has proved to be highly accurate and has replaced preoperative angiography in almost all cases. It provides all of the information required for preoperative and intraoperative planning in nephron-sparing surgery in a single test. The three-dimensional video format allows the surgeon to appreciate the pertinent findings and has proved to be highly useful to urologists in preoperative and intraoperative surgical planning.

Prospective comparison of 3-dimensional volume rendered computerized tomography and conventional renal arteriography for surgical planning in patients undergoing laparoscopic donor nephrectomy

PURPOSE

We prospectively assessed the accuracy of 3-dimensional (3-D) volume rendered computerized tomography (CT) and conventional renal arteriography to visualize renovascular anatomy in patients undergoing laparoscopic donor nephrectomy.

MATERIALS AND METHODS

A total of 60 consecutive patients undergoing laparoscopic donor nephrectomy (left side in 46 and right side in 14) prospectively underwent 3-D CT and renal angiography. A short videotape of 3-D CT was prepared using volume rendering software that demonstrated the anatomical location, number, anomalies and spatial interrelationships of the renal arteries and veins. These 3-D videotapes and arteriogram findings were directly correlated with intraoperative surgical findings at laparoscopy and during ex vivo bench preparation of the harvested kidney. The perceived intraoperative value of 3D-CT to delineate renovascular anatomical detail was scored subjectively by the laparoscopic surgeon for each case on a 10-point scale of 0--completely inaccurate to 10--completely accurate.

RESULTS

There were no complications related to the 3-D CT protocol and volume rendering was successful in all patients. Three-D CT accurately identified the number of renal arteries in 59 patients (98%). In 1 patient with 3 renal arteries 3-D CT and arteriogram each identified only 2. In the 46 patients undergoing left donor nephrectomy 3-D CT accurately identified the number of veins and venous anomalies in 45 (98%), including 2 with a circumaortic left renal vein. Another case of circumaortic vein was misdiagnosed as 2 renal veins. On the right side in 14 patients 3-D CT accurately identified the renal veins in 13 (94%) and missed 1 vein in a patient with 2 renal veins. Angiography correctly identified the number of renal veins in only 52 cases (87%). Furthermore, it misdiagnosed all 3 cases of circumaortic left renal vein. The laparoscopic surgeon believed that 3-D CT accurately identified the location and anatomical interrelationship of the renal vessels with precision. Mean subjective score +/- SEM was 8.5 +/- 1 for the arterial system, 8.6 +/- 1.1 for the venous system and 9.2 +/- 0.5 for any vascular anomalies.

CONCLUSIONS

Three-D CT accurately identifies renal vascular anatomy in a manner that may facilitate renal hilar dissection during laparoscopic donor nephrectomy, especially during the initial surgeon experience. This imaging modality integrates essential information from angiography, venography and excretory urography into a single study, and it can obviate the need for more invasive vascular imaging in most cases.

Comparative analysis of laparoscopic versus open partial nephrectomy for renal tumors in 200 patients

PURPOSE

Laparoscopic partial nephrectomy is an emerging minimally invasive, nephron sparing approach for renal cell carcinoma. We compared perioperative outcomes after laparoscopic and open nephron sparing surgery (NSS) for patients with a solitary renal tumor of 7 cm or less at a single institution.

MATERIALS AND METHODS

Since September 1999, 100 consecutive patients have undergone laparoscopic partial nephrectomy for a sporadic single renal tumor of 7 cm or less at our institution. A contemporary cohort of 100 consecutive patients with similar inclusion criteria have undergone open NSS since April 1998. Since our laparoscopic technique was based on our established open surgical principles, the 2 approaches were similar, including transient renal vascular control, sharp tumor excision in a bloodless field, pelvicaliceal repair when necessary, suture ligation of transected intrarenal blood vessels and suture repair of the renal parenchymal defect over a bolster. Demographic, intraoperative, postoperative and short-term followup data were retrospectively compared between the 2 groups.

RESULTS

Median tumor size was 2.8 cm in the laparoscopic group and 3.3 cm in the open group (p = 0.005). There were significantly more tumors greater than 4 cm in the open group (p <0.001). There were more patients with a solitary kidney in the open surgical group (p = 0.002). More patients in the open group underwent NSS for a malignant tumor (p = 002). Comparing the laparoscopic versus open groups, median surgical time was 3 vs 3.9 hours (p <0.001), blood loss was 125 vs 250 ml (p <0.001) and mean warm ischemia time was 27.8 vs 17.5 minutes (p <0.001), respectively. In the laparoscopic and open groups median analgesic requirement was 20.2 vs 252.5 mg morphine sulfate equivalents (p <0.001), hospital stay was 2 vs 5 days (p <0.001) and average convalescence was 4 vs 6 weeks (p <0.001). Median preoperative serum creatinine (1.0 vs 1.0 mg/dl, p = 0.52) and postoperative serum creatinine (1.1 vs 1.2 mg/dl, p = 0.65) were similar in the 2 groups. No kidney was lost due to warm ischemic injury. Three patients in the laparoscopic group had a positive surgical margin compared to none in the open groups (3% vs 0%, p = 0.1). Laparoscopic NSS was associated with a higher rate of major intraoperative complications (5% vs 0%, p = 0.02). There were no significant differences in overall postoperative complications, although renal/urological complications were more common in the laparoscopic group (11% vs 2%, p = 0.01).

CONCLUSIONS

Open surgical partial nephrectomy remains the established standard for nephron sparing treatment of renal tumors. When applied to small renal tumors, the laparoscopic approach is associated with longer warm renal ischemia time, more major intraoperative complications and more postoperative urological complications. Our data also suggest that more deliberate efforts to achieve a wider surgical margin are necessary with the laparoscopic approach. Nevertheless, our data suggest that laparoscopic NSS is emerging as an effective, minimally invasive therapeutic approach with respect to renal functional outcome with the additional advantages of decreased postoperative narcotic use, earlier hospital discharge and a more rapid convalescence. Continued efforts are required to develop laparoscopic renal hypothermia techniques and facilitate intrarenal suturing, while minimizing warm ischemia time.

Imaging for renal tumors

PURPOSE OF REVIEW

The present review summarizes current developments in the imaging of renal tumors.

RECENT FINDINGS

Computed tomography (CT), magnetic resonance imaging, and ultrasound are used for diagnosing, characterizing, and staging renal tumors. Recent advances have been made in many areas, but the most significant changes have occurred in helical CT. The traditional roles for CT and magnetic resonance imaging have been expanded to include the use of three-dimensional CT and magnetic resonance imaging as surgical planning tools. Three-phase CT scans are commonly performed for detection, characterization, and staging of renal lesions, but pelvic CT is probably not needed for preoperative staging. Three-phase CT scans are more sensitive for characterization and for identifying the renal vasculature. Enhancement characteristics on these scans can help to distinguish between different tumor types. Finally, CT urography is a promising alternative to conventional excretory urography, with the potential to simplify the imaging evaluation of patients with hematuria.

SUMMARY

Although ultrasound and magnetic resonance imaging have many indications for imaging renal tumors, CT, with new uses and improved diagnostic capabilities, remains the gold standard in renal imaging.

High-resolution multidetector CT in the preoperative evaluation of patients with renal cell carcinoma

OBJECTIVE

The purpose of our study was to evaluate the accuracy of multidetector CT (MDCT) using a high-resolution protocol in the preoperative assessment of patients with renal cell carcinoma who are possible candidates for nephron-sparing surgery.

MATERIALS AND METHODS

Forty patients with suspected renal cell carcinoma underwent MDCT. Contrast-enhanced acquisitions were obtained during arterial, nephrographic, and urographic phases using a thin-slice protocol. One-millimeter-thick source images were evaluated by two observers on a dedicated workstation for the identification and characterization of the tumor, presence of a pseudocapsule or invasion of perirenal fat, involvement of adrenal glands or surrounding tissues, presence of satellite lesions within Gerota's fascia, infiltration of renal vein and inferior vena cava, involvement of lymph nodes, and presence of distant metastases. Imaging findings were compared with surgical specimens using criteria from the Robson and TNM classification systems.

RESULTS

The presence and size of all lesions were correctly shown in all patients. In evaluating Robson stage I of renal cell carcinoma, we were able to diagnose fat infiltration on 1-mm scans with 96% sensitivity, 93% specificity, and 95% accuracy; the positive and negative predictive values were, respectively, 100% and 93%. One hundred percent accuracy was achieved in staging high-grade lesions.

CONCLUSION

High-resolution MDCT is accurate in the preoperative evaluation of patients with renal cell carcinoma.

Renal MDCT

Multidetector CT has expanded the utility of CT by improving longitudinal resolution and acquisition speed. Applications include diagnosis of renal vascular and parenchymal injuries, renal tumor diagnosis and staging, the emerging field of CT urography and CT angiography. This summary review illustrates MDCT approaches to the evaluation of trauma, suspected tumor and imaging of the urinary tract and discusses other applications in renal inflammatory disease, urolithiasis and renal anomalies.

Three-dimensional navigator for retroperitoneal laparoscopic nephrectomy using multidetector row computerized tomography

PURPOSE

We evaluated the efficacy of a 3-dimensional (D) navigator for retroperitoneal laparoscopic nephrectomy.

MATERIALS AND METHODS

A total of 21 patients with malignant localized renal (16) or ureteral (5) neoplasms underwent multi-detector row computerized tomography. The 3-D navigator was created using volume rendering technique. These findings were compared with videos obtained during laparoscopy.

RESULTS

The 3-D navigator depicted all renal arteries (100% sensitivity) and 24 of the 25 renal veins (96% sensitivity). Hilar anatomy, including the tumor, major vessels and adrenal gland, and their relationships were visualized as in laparoscopic views.

CONCLUSIONS

The 3-D navigator has a potentially important role in retroperitoneal laparoscopic nephrectomy. It is able to guide surgeons and aid in avoiding operative risks and possible complications.