Three-dimensional Volume-rendered Helical CT before Laparoscopic Adrenalectomy

Three-dimensional CT cinematic rendering of adrenal masses: Role in tumor analysis and management

The adrenal gland is home to an array of complex physiological and neoplastic disease processes. While dedicated adrenal computed tomography (CT) is the gold standard imaging modality for adrenal lesions, there exists significant overlap among imaging features of adrenal pathology. This can often make radiological diagnosis and subsequent determination of the optimal surgical approach challenging. Cinematic rendering (CR) is a novel CT post-processing technique that utilizes advanced light modeling to generate highly photorealistic anatomic visualization. This generates unique prospects in the evaluation of adrenal masses. As one of the first large tertiary care centers to incorporate CR into routine diagnostic workup, our preliminary experience with using CR has been positive, and we have found CR to be a valuable adjunct during surgical planning. Herein, we highlight the unique utility of CR techniques in the workup of adrenal lesions and provide commentary on the opportunities and obstacles associated with the application of this novel display method in this setting.

Utility of right adrenal signature veins in venous sampling for primary aldosteronism

BACKGROUND

This study aimed to identify the appropriate signature veins for the right adrenal gland using a 3D model fused with adrenal venography images and to verify their accuracy through the selectivity index (SI) >2.

METHODS

We analyzed the right adrenal venography images of 41 patients who underwent adrenal venous sampling (AVS). These images were merged with a 3D structure of the adrenal gland to identify the signature veins of the right adrenal gland. We then used the signature veins observed during adrenal venography to determine the optimal position of the catheter tip during AVS for 53 other patients. Finally, we verified the accuracy of this method according to the SI.

RESULTS

We successfully fused the 3D models of 41 cases with adrenal venography images. We identified the trunk branch type as the major venous morphology in the right anterior oblique at degrees of 30 (38 cases, 92.7%). In addition, the central vein, brush vein, uvula vein, and capsular vein were identified as signature veins for the right AVS. The accuracy of AVS was 100% in the other 53 patients, as verified by an SI >2.

CONCLUSIONS

Our study identified the right adrenal signature veins, including the previously overlooked uvula vein, which can be used to determine the position of the catheter tip and improve the success rate of AVS.

Distinguishing pheochromocytoma from adrenal adenoma by using modified computed tomography criteria

PURPOSE

To investigate the performance of modified criteria to distinguish pheochromocytoma from adrenal adenoma by using adrenal protocol computed tomography (CT).

METHODS

We retrospectively included consecutive 199 patients who underwent adrenal CT and surgically proven pheochromocytoma (n = 66) or adenoma (n = 133). Two independent radiologists analyzed two CT criteria for pheochromocytoma. Conventional criteria were as follows: (a) lesion attenuation on unenhanced CT > 10 Hounsfield unit (HU); (b) absolute percentage washout < 60%; and (c) relative percentage washout < 40%. Modified criteria were as follows: (a) conventional criteria or (b) one of the following findings: (i) lesion attenuation on unenhanced CT ≥ 40 HU, (ii) 1-min enhanced CT ≥ 160 HU, (iii) 15-min enhanced CT ≥ 70 HU, , or (iv) intralesional cystic degeneration seen on both 1-min and 15-min enhanced CT. We analyzed area under the curve (AUC) and inter-reader agreement.

RESULTS

Proportion of pheochromocytoma was 33.2% (66/199). AUC of modified criteria was consistently higher than that of conventional criteria for distinguishing pheochromocytoma from adenoma (reader 1, 0.864 versus 0.746 for raw data set and 0.865 versus 0.746 for internal validation set; reader 2, 0.872 versus 0.758 for raw data set and 0.872 versus 0.757 for internal validation set) (p < 0.05 for all comparisons). Inter-reader agreement was excellent in interpreting any criteria (weighted kappa > 0.800).

CONCLUSION

Our modified criteria seem to improve diagnostic performance of adrenal CT in distinguishing pheochromocytoma from adrenal adenoma.

Real-time structured light-based otoscopy for quantitative measurement of eardrum deformation

An otological profilometry device based on real-time structured light triangulation is presented. A clinical otoscope head is mounted onto a custom-handheld unit containing both a small digital light projector and a high-speed digital camera. Digital fringe patterns are projected onto the eardrum surface and are recorded at a rate of 120 unique frames per second. The relative angle between projection and camera axes causes the projected patterns to appear deformed by the eardrum shape, allowing its full-field three-dimensional (3-D) surface map to be reconstructed. By combining hardware triggering between projector and camera with a dedicated parallel processing pipeline, the proposed system is capable of acquiring a live stream of point clouds of over 300,000 data points per frame at a rate of 40 Hz. Real-time eardrum profilometry adds an additional dimension of depth to the standard two-dimensional otoscopy image and provides a noninvasive tool to enhance the qualitative depth perception of the clinical operator with quantitative 3-D data. Visualization of the eardrum from different perspectives can improve the diagnosis of existing and the detection of impending middle ear pathology. The capability of the device to detect small middle ear pressure changes by monitoring eardrum deformation in real time is demonstrated.

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.

Adrenal imaging: a comprehensive review

The discovery of an incidental adrenal mass (adrenal incidentaloma) continues to rise with the increasing use of cross-sectional imaging. Although most adrenal lesions are benign and asymptomatic, radiologists should guide evaluation of these lesions, whether benign or malignant. This article reviews the various imaging techniques used to evaluate adrenal masses and their relative strengths and weaknesses. It focuses on the most prevalent adrenal pathologies and their typical imaging characteristics, and concludes with a brief discussion of developing techniques, including diffusion-weighted imaging and dual-energy CT.

Adrenal imaging with multidetector CT: evidence-based protocol optimization and interpretative practice

Computed tomography (CT) is an integral tool in the assessment of adrenal masses. Dedicated adrenal CT is performed for a range of indications, including hormonal abnormalities suggestive of a functional adrenal mass and adrenal cancer staging. It is important to have an understanding of the published data that guide protocol design and image interpretation. Whether an adrenal mass is identified serendipitously or is being imaged for further characterization, there are several CT findings that contribute to the diagnosis, such as lesion size, precontrast attenuation, level of enhancement at 60 seconds and on delayed images, percentage washout on delayed images, histogram analysis, and extent (involvement of the inferior vena cava and bilaterality). In the past decade, a body of pertinent literature has evolved, addressing each of these measures individually.

The use of three-dimensional computed tomography for assessing patients before laparoscopic adrenal-sparing surgery

OBJECTIVE

To evaluate the efficacy of three-dimensional computed tomography (3D-CT) in delineating the relationship of the adrenal mass to adjacent normal structures in preparation for laparoscopic partial adrenalectomy.

PATIENTS AND METHODS

Multislice CT (1 mm slices, 0.5 s rotation time) was used to evaluate 12 patients before adrenal-sparing surgery for aldosterone-producing adenoma or phaeochromocytoma. The CT data were reconstructed using two rendering techniques; (i) volume rendering with the modified VOLREN software (Johns Hopkins Hospital, Baltimore, MD, USA) which allowed interactive 3D examination of the whole data volume within a few minutes; (ii) surface representations only of the interesting structures (kidney, adrenal tumour, vessels) represented in different colours and depicted together in a 3D scene using the software package 3DVIEWNIX.

RESULTS

In all, 14 adrenal masses in 12 patients were evaluated with 3D-CT; the number and location of lesions was accurate in all cases with both rendering techniques. The coloured surface-rendered images showed a consistently better delineation of the adrenal tumour from the normal tissue than did the volume-rendering technique. From this information all laparoscopic partial adrenalectomies could be completed as planned.

CONCLUSIONS

Interactive visualization of volume-rendered CT images was helpful for the planning and successful performance of the procedure, but coloured surface-rendered CT provided more convenient, immediate and accurate intraoperative information.

Retroperitoneal hand-assisted laparoscopic surgery for endoscopic adrenalectomy

Although hand-assisted laparoscopic surgery (HALS) is very common in various laparoscopic procedures, it is rarely used for retroperitoneal endoscopic adrenalectomy because of the small working area. The authors evaluate HALS in endoscopic adrenalectomy with respect to its use as a rescue procedure in complicated cases. In their department, 47 patients underwent endoscopic adrenalectomies between 1998 and 2004. Mainly because of complicated anatomy, three primary aldosteronism cases were converted to retroperitoneal HALS. This involved making an additional 6 cm skin incision, into which the surgeon's left hand was inserted, with the palm used to create a sufficient visual field and working area. The fingers were used for tactile sensation and blunt resection. For these three cases, successful retroperitoneal HALS in endoscopic adrenalectomy resulted in no mortality or morbidity. These findings indicate that this procedure is a feasible technique for complicated benign adrenal tumor cases.

Imaging findings of biliary and nonbiliary complications following laparoscopic surgery

Laparoscopic techniques are evolving for a wide range of surgical procedures although they were initially confined to cholecystectomy and exploratory laparoscopy. Recently, surgical procedures performed with a laparoscope include splenectomy, adrenalectomy, gastrectomy, and myomectomy. In this article, we review the spectrum of complications and illustrate imaging features of biliary and nonbiliary complications after various laparoscopic surgeries. Biliary complications following laparoscopic cholecystectomy include bile ductal obstruction, bile leak with bile duct injury, dropped stones in the peritoneal cavity, retained CBD stone, and port-site metastasis. Nonbiliary complications are anastomotic leakage after partial gastrectomy, gangrenous cholecystitis after gastrectomy, hematoma at the anastomotic site following gastrectomy, gastric infarction after gastrectomy, port-site metastasis after gastrectomy, hematoma after splenectomy, renal infarction after adrenalectomy, and active bleeding after myomectomy of the uterus.

[Computer-assisted operational planning for pediatric abdominal surgery. 3D-visualized MRI with volume rendering]

Exact surgical planning is necessary for complex operations of pathological changes in anatomical structures of the pediatric abdomen. 3D visualization and computer-assisted operational planning based on CT data are being increasingly used for difficult operations in adults. To minimize radiation exposure and for better soft tissue contrast, sonography and MRI are the preferred diagnostic methods in pediatric patients. Because of manifold difficulties 3D visualization of these MRI data has not been realized so far, even though the field of embryonal malformations and tumors could benefit from this.A newly developed and modified raycasting-based powerful 3D volume rendering software (VG Studio Max 1.2) for the planning of pediatric abdominal surgery is presented. With the help of specifically developed algorithms, a useful surgical planning system is demonstrated. Thanks to the easy handling and high-quality visualization with enormous gain of information, the presented system is now an established part of routine surgical planning.