Three-dimensional imaging and display of renal tumors using spiral CT: a potential aid to partial nephrectomy

New Generation of 3D Virtual Models with Perfusional Zones: Perioperative Assistance for the Best Pedicle Management during Robotic Partial Nephrectomy

Selective clamping during robot-assisted partial nephrectomy (RAPN) may reduce ischemia-related functional impairment. The intraoperative use of 3D-virtual models (3DVMs) can improve surgical planning, resulting in a greater success rate for selective clamping. Our goal is to introduce a new generation of 3DVMs, which consider the perfusion volumes of the kidney. Patients listed for RAPN from 2021 to 2022 were recruited. A selective clamping strategy was designed and intraoperatively performed based on the specifically generated 3DVMs. The effectiveness of selective clamping was evaluated using near-infrared-fluorescence imaging (NIRF) and 3DVM. Perfusion areas extensions were compared, and relevant preoperative characteristics were analyzed. In 61 of 80 (76.25%) cases, selective clamping was performed. The concordance between the 3DVM areas and the NIRF-enhanced areas was verified (k = 0.91). According to the distribution of perfused areas crossing the tumor, there were one, two, three, four, and five crossing areas, with relative perfusion rates of 13.75%, 35%, 32.5%, 13.75%, and 5%, respectively. Lesion diameter and mesorenal location were the only factors related to a higher number (>3) of perfusion volumes crossing the lesion. The implementation of mathematical algorithms to 3DVMs allows for precise estimation of the perfusion zone of each arterial branch feeding the organ, leading to the performance of safe and effective pedicle management planning.

3D CT of renal pathology: initial experience with cinematic rendering

3D computed tomography (CT) visualizations of volumetric data have become an important aspect of diagnostic imaging. The utility of 3D CT has been well described for the imaging of a number of renal pathologies. Recently, a new 3D visualization technique known as cinematic rendering (CR) has become available and provides photorealistic images derived from standard CT acquisitions by use of a complex global lighting model. Herein, we describe a number of normal variant and pathologic conditions of the kidney visualized with CR. We provide comparisons of findings with CR to traditional methods of 3D imaging and comment on the potential applications of this new method of 3D CT rendering.

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.

Imaging of kidney cancer

Advances in molecular genetics have expanded the understanding of renal cell tumors. Now it is understood that renal cortical tumors are a family of neoplasms with distinct cytogenetics and molecular defects, unique histopathologic features, and different malignant potentials. Imaging contributes to clinical management of patients with renal tumors in providing diagnostic information for tumor detection, characterization, staging, treatment planning, and follow-up.

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.

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.

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.

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.

Computed tomography urography, three-dimensional computed tomography and virtual endoscopy

Spiral computed tomography technology allows an entire body region to be imaged as a continuous volume of computed tomography data. The acquisition of genitourinary images can be performed at different intervals after intravenous contrast injection in order to characterize the renal vasculature, the renal parenchyma or the collecting system. Computed tomography scanning as contrast is excreted into the collecting system is termed a 'computed tomography urogram'. Volumetric data from spiral computed tomography can be rendered into conventional two-dimensional images or even reformatted into three-dimensional views of organ systems or hollow structures, as in 'fly-through' virtual endoscopy. Although virtual endoscopy of the urinary tract remains in its infancy, three-dimensional imaging is currently a useful adjunct in the evaluation of renal transplant and donor patients and partial nephrectomy candidates. The role of computed tomography urography compared with intravenous urography in the evaluation of hematuria is discussed.

Tumor detection by virtual cystoscopy with color mapping of bladder wall thickness

PURPOSE

We determine the value of color mapping of bladder wall thickness for detection of tumor as a component of virtual cystoscopy.

MATERIALS AND METHODS

A total of 31 subjects with hematuria and/or a history of bladder tumor underwent helical computerized tomography of the pelvis after distention of the bladder with air. Three-dimensional (D) models were constructed, and thickness of the wall was color mapped according to a fixed and validated mm. scale. Axial source images and 3-D models were reviewed and graded for the presence of wall thickening. A comparison was made with findings on conventional cystoscopy in 31 patients and pathological specimen in 13.

RESULTS

Compared with conventional cystoscopy, the analysis of axial image yielded a sensitivity of 0.80, specificity 0.90, positive predictive value 0.80 and negative predictive value 0.90 for the presence of tumor. Examination of color mapped 3-D renderings resulted in 0.83, 0.36, 0.42 and 0.71, respectively.

CONCLUSIONS

Thin axial computerized tomography of the air distended bladder shows promise as a potential screening tool for bladder cancer. The low specificity of color mapped 3-D renderings makes the technique inappropriate for screening. It may valuable for guiding urologists to additional suspicious sites in a patient with a known tumor.

Three-dimensional CT of the genitourinary tract

The applications of three-dimensional (3D) CT techniques encompass a spectrum from calculus disease to preoperative planning. With proper selection of display windows and levels, accurate measurement of stone size can be achieved, along with volumetric information. A CT scan with reconstruction may help guide the direction of an endopyelotomy incision away from crossing vessels. The benefits of 3D CT in the evaluation of living renal donors include lower cost and decreased patient morbidity. In renal allograft recipients and other patients, the study may be used to investigate hypertension. Also, 3D CT is invaluable in planning nephron-sparing surgery for renal masses. The ultimate role of this modality rests in the hands of clinicians who can benefit from them and the radiologists who must provide the high-quality images and the interpretive expertise.

Preoperative simulation of partial nephrectomy with three-dimensional computed tomography

OBJECTIVE

To evaluate prospectively the accuracy of computer-aided three-dimensional (3D) volume-rendered computed tomography (CT) in determining the appropriate anatomical limits (tumour size, tumour location, multifocality and vascular supply) and as a potential tool in the preoperative simulation of nephron-sparing surgery (NSS) in patients with small-volume renal cell carcinoma (RCC).

PATIENTS AND METHODS

The study included 36 patients who underwent transperitoneal radical nephrectomy for RCC of < 4 cm diameter. Helical CT was undertaken before surgery and the extent of the tumour, the course of major renal arteries and veins, and the relationship of the tumour to the collecting system were shown by 3D volume-rendered CT. The CT findings were compared with the pathological results of all kidney specimens, obtained using 3-mm step-sections.

RESULTS

Before nephrectomy, 39 renal tumours were identified in the 36 patients; three renal lesions of < 4 mm were not detected. All main venous branches and 42 of 43 arteries were identified by 3D volume-rendered CT. Knowing these features, a partial nephrectomy was simulated; a surgical lesion to the pelvicalyceal or vascular system which would have been produced by the simulated surgery was displayed in colour on the simulated surface of the section.

CONCLUSION

Computer simulation provided an excellent 3D reconstruction of all kidneys, including the tumour, vasculature and renal hilum, allowing a significantly better preoperative evaluation of the renal mass. Visualizing possible resection margins and predicting the operative risks seem to be major advantages of this new method, especially when preparing for complex surgery. Reconstructed 3D CT appears to be a useful tool for defining the indications for and limitations of NSS.

Current Status of Partial Nephrectomy in the Management of Kidney Cancer

BACKGROUND: The technique of partial nephrectomy for managing renal cancers is well recognized, but guidelines regarding indications for its use are not generally accepted. METHODS: The authors review the indications for partial nephrectomy in various clinical situations, and they include their own experience to clarify the utility of the technique. RESULTS: Intraoperative renal ultrasound and helical computed tomography can assist the surgeon in technical decisions. Partial nephrectomy is considered when nephrectomy would render the patient anephric and dependent on dialysis. CONCLUSIONS: The technical and operative advances in partial nephrectomy make the approach increasingly attractive for patients with kidney cancer in a variety of clinical circumstances.

Abdominal MR imaging with a volumetric interpolated breath-hold examination

PURPOSE

To compare a T1-weighted, three-dimensional (3D), gradient-echo (GRE) sequence for magnetic resonance (MR) imaging of the body (volumetric interpolated breath-hold examination, or VIBE) with a two-dimensional (2D) GRE breath-hold equivalent.

MATERIALS AND METHODS

Twenty consecutive patients underwent 1.5-T MR imaging. The examinations included pre- and postcontrast (20 mL gadopentetate dimeglumine) fat-saturated 2D GRE breath-hold imaging and fat-saturated volumetric interpolated breath-hold imaging before, during (arterial phase), and after injection, with thin (2-mm source images) and thick (8-mm reconstruction images) sections. The three images were compared qualitatively and quantitatively (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]).

RESULTS

Qualitatively, the 2-mm source images had poorer pancreatic edge definition on precontrast images compared with the other two data sets (P < .05). On gadolinium-enhanced images, scores for clarity of pancreatic edge, number of vessels visualized, and arterial ghosting were significantly lower for the postcontrast 2D GRE images. Quantitatively, SNR measurements in the liver, aorta, and renal cortex on pre- and postcontrast images were significantly higher for the 8-mm reconstruction images than for the 2D GRE or 2-mm source images (P < .05). Aorta-to-fat CNR was significantly higher on the 8-mm reconstruction images.

CONCLUSION

Fat-saturated volumetric interpolated breath-hold images have quality comparable to that of conventional fat-saturated 2D GRE images.

Three-dimensional CT angiography: renal applications

CT angiography has become an effective noninvasive imaging modality for evaluating the renal vasculature. The current clinical applications for CT angiography and three-dimensional (3D) imaging related to the kidneys and renal vasculature include evaluation of renal artery stenosis, renal diseases related to aortic diseases, living-related renal donor candidates, and preoperative evaluation of renal masses for possible nephron sparing surgeries. Imaging parameters need to be individually prescribed for renal CT angiography depending on the diagnostic goal of the examination. Methods for optimizing spiral CT protocols including patient preparation, contrast administration, image acquisition parameters, and image reconstruction will be covered.

Helical CT with multiplanar display: role in evaluation and clarification of complex renal pathology

Helical CT provides an accurate tool in the diagnosis and detection of renal disease. A major advantage of renal helical CT is the ability to obtain a volumetric dataset during optimal vascular and parenchymal enhancement. In addition, multiplanar display improves demonstration of key anatomic relationships and clarifies complex pathology. In this essay, we demonstrate the advantages of multiplanar display in evaluation of the kidney.

Surgical enucleation for renal cell carcinoma (RCC). Prognostic significance of tumour stage, grade and DNA ploidy

This study reviews a total of 26 renal cell carcinoma (RCC) who underwent enucleation of the tumour with functionally and anatomically normal controlateral kidney and no evidence of systemic renal disease. At follow-up, after a mean of 62 months the disease specific survival rate for this series was 88.5%. Survival rates according to the pathologic stage, grading, tumour diameter and ploidy are reported. Local recurrences were documented in 4 of the 26 RCC. All 4 RCC were more than 5 cm in diameter and recurred in the remaining parenchyma. After local recurrence, three tumours with aneuploid DNA content underwent radical nephrectomy, whereas 1 with diploid DNA content was submitted to a new enucleation of the recurrence. To date the diploid case is still alive 3 years after the original resection of the primary tumour whereas the other 3 patients died for metastatic disease. In our experience the ideal candidate for renal sparing surgery in the presence of a normal opposite kidney is an asymptomatic patient that incidentally is brought to our attention with a small size (less than 5 cm in diameter), low stage (T1-T2) tumour, well surrounded by a pseudocapsule. DNA content is a valuable prognostic factor in patients submitted to conservative surgery. Diploid tumours have been seen to have a better prognosis and in case of local recurrence they may be reconsidered for a new enucleation of the recurrence.

Spiral CT: clinical applications in the gastrointestinal tract

Spiral CT provides the ability to acquire single breathhold volume acquisitions that allow for optimization of the infusion of iodinated contrast material and CT data acquisition. Although initial applications focused on the chest, liver, and vascular system, spiral CT has important implications for the tubular structures of the GI tract (esophagus, stomach, small bowel, and colon). Tumor detection and staging may be optimized by these better datasets which also provide multiplanar and 3D imaging capabilities. This article reviews many of these specific applications and emphasizes the potential value of spiral CT scanning.

Imaging in the staging of renal cell carcinoma

Imaging is extremely important in determining the type of surgery undertaken in patients with proven renal cell carcinoma. In this review, the strength and limitations of each of the relevant techniques are outlined, highlighting particularly the correlation between the imaging findings and the pathological staging. Over the past decade, CT has become the most widely used technique for staging renal cell carcinoma, partly due to the very high overall accuracy of up to 90% that has been achieved. MRI appears to have a similar overall accuracy to CT, whereas ultrasound is less accurate than CT or MRI in the overall staging of tumours. However, ultrasound is extremely accurate in identifying and localising the clinically important tumour extension into the intra-hepatic vena cava and right atrium and if local surgical practice requires only a knowledge of venous invasion, a technically adequate ultrasound examination may suffice. All techniques are unreliable in detecting early perinephric spread.

The current state of the art in three dimensional oncologic imaging: an overview

PURPOSE

To provide an overview of the methods and clinical applications of three dimensional (3D) medical imaging in the oncologic patient.

METHODS AND MATERIALS

We briefly outline the techniques currently used to create 3D medical images with an emphasis on their strengths and shortcomings as they relate to oncologic imaging and radiation therapy planning. We then discuss some of the most important and promising oncologic applications of 3D imaging and suggest likely future directions in this rapidly developing field.

RESULTS

Since the first application of 3D techniques to medical data over a decade ago, 3D medical images have evolved from relatively crude representations of musculoskeletal abnormalities to detailed and accurate representations of a variety of soft tissue, vascular, and oncologic pathology. The rapid development of both computer hardware and software coupled with the application of 3D techniques to a variety of imaging modalities have expanded the clinical applications of this technology dramatically.

CONCLUSIONS

3D medical images are clinically practical tools for oncologic evaluation and effective radiation therapy planning.

Noninvasive angiography in preoperative evaluation of complicated pediatric renal masses using phase contrast magnetic resonance angiography

OBJECTIVES

To report a new technique called "phase contrast magnetic resonance angiography" (PC MRA) utilizing phase contrast magnetic resonance imaging, for assessing the renal vasculature in relation to complicated pediatric renal masses.

METHODS

Three-dimensional phase contrast gradient refocused pulse sequences were obtained on four pediatric patients with complicated renal masses. Findings were compared to ultrasound and computed tomographic images and correlated with actual surgical anatomy.

RESULTS

In all four cases PC MRA provided standard angiographic quality detail of the renal vascular anatomy. The PC MRA findings had a 100% correlation with surgical exploration and MRA proved to be approximately one third the cost of the standard angiographic technique.

CONCLUSIONS

Our experience with the use of PC MRA in children suggests that it can be helpful in evaluating the vasculature of complicated pediatric renal masses. PC MRA utilizes current generation magnetic resonance units, is noninvasive, and does not require anesthesia. It may be especially useful in patients with hypersensitivity to contrast agents, in those with renal failure in whom contrast agents may be contraindicated, and is less expensive than standard angiography.