Can radiological assessment of abdominal computerized scans diagnose encapsulating peritoneal sclerosis in long-term peritoneal dialysis patients?

AIM: Encapsulating peritoneal sclerosis (EPS) is a rare but potentially devastating complication of long-term peritoneal dialysis (PD). Changes to the peritoneal membrane occur with duration of PD therapy. To determine the potential effect of prospective computerized tomography (CT) scanning, we reviewed the scans of patients who had developed EPS compared with those without EPS. METHODS: We retrospectively compared CT scans that had been prospectively performed in a screening program for PD patients after 4 years of PD and compared scans from 18 patients with confirmed EPS and 26 vintage matched controls without EPS. Anonymized scans were reported independently by two blinded experienced radiologists. RESULTS: Peritoneal thickening, calcification, bowel tethering, thickening and dilatation were significantly more commonly reported in the EPS group. Total combined radiological scores, also including septation within peritoneal fluid, were significantly higher in the EPS group and the greatest for those who died as a consequence of EPS. Simplified scoring based on presence or absence, then for a score of ≥3.0, gave a receiver operating characteristic value of 0.87 for EPS, with a sensitivity of 78% and specificity of 85%, respectively. Inter-observer agreement varied from poor to good, being the greatest for calcification and bowel dilatation and the lowest for peritoneal thickening. CONCLUSION: CT scan reporting can differentiate EPS from peritoneal changes associated with duration of PD therapy. Severity of abnormalities was associated with clinical outcomes. However, inter-observer agreement varies with different radiological appearances, and future studies are required to determine weighting of radiological changes to provide prognostic information for clinicians and patients.

Complications of continuous ambulatory peritoneal dialysis.

Continuous ambulatory peritoneal dialysis (CAPD) is used to treat end-stage renal failure in an increasing number of patients. CAPD has an advantage over hemodialysis in that it allows patients greater freedom to perform daily activities; it also provides other clinical benefits. However, the long-term effectiveness of CAPD is limited by complications, which have various causes. Complications with an infectious cause include bacterial peritonitis, tuberculous peritonitis, and infections of the catheter exit site and tunnel. Noninfectious complications include catheter dysfunction, dialysate leakage, hernias, and sclerosing encapsulating peritonitis. Many imaging modalities-radiography, ultrasonography, peritoneal scintigraphy, computed tomography (CT), and magnetic resonance (MR) imaging-are useful for characterizing these complications. CT peritoneography and MR peritoneography are techniques specifically suited to this purpose. Imaging plays a critical role in ensuring that complications are detected early and managed appropriately.

Breast cancers: noninvasive method of preoperative localization with three-dimensional US and surface contour mapping.

Formal ethical approval was granted by the local research ethics committee; all participants gave written consent. The purpose of the study was to prospectively evaluate the feasibility of a noninvasive method of breast tumor localization in 25 participants, based on the coregistration of three-dimensional (3D) ultrasonographic (US) data with surface contour data obtained by using a 3D laser camera. The tumor is segmented from the US data, and a surface-rendered 3D image of the tumor, in relation to the breast surface contour, is produced. From a personal computer in the operating room, the surgeon can dynamically view a 3D image of the tumor within the breast. This noninvasive method was equivalent to conventional techniques in 18 of 25 patients but was less successful in larger-breasted patients. In selected patients, this localization method could provide an alternative to conventional invasive techniques and can offer both spatial localization and tumor morphology.

High definition three-dimensional ultrasound to localise the tumour bed: a breast radiotherapy planning study.

BACKGROUND AND PURPOSE: Complex radiation techniques, such as conformal radiotherapy for partial breast irradiation, require accurate localisation of the tumour bed. This study investigated high definition 3D ultrasound for breast tumour bed localisation. Study aims were: firstly, to determine how easily a tumour cavity could be visualised with 3D ultrasound; secondly, to determine the accuracy of computed tomography (CT) and 3D ultrasound co-registration; thirdly, to compare 3D ultrasound with other methods of localisation. MATERIALS AND METHODS: 3D ultrasound examinations were carried out in 40 women attending for breast radiotherapy. 3D position data were co-registered with the radiotherapy planning CT. 2D ultrasound and CT, surgical clips and CT, and CT alone were also used to localise the tumour bed in 32/40, 14/40 and 5/40 patients, respectively. Tumour bed volume and centre of gravity measurements for all methods of localisation were compared. RESULTS: Mean surgery to imaging interval was 44 days (range 23-86 days). The post-operative cavity was seen in all cases using the 3D ultrasound, and was graded as highly visible, visible and subtle in 21/40 (53%), 12/40 (30%) and 7/40 (17%) cases, respectively. There was a statistically significant improvement in the ability of 3D ultrasound to localise the tumour bed compared with 2D ultrasound. CT-ultrasound registration was achieved in all cases. Two-dimensional and 3D ultrasound showed smaller tumour bed volumes than clips. CONCLUSIONS: Three-dimensional ultrasound localisation of the tumour bed appears superior to 2D ultrasound. It can also be co-registered with a planning CT, thus allowing additional information on the size and location of the tumour bed to be integrated into complex radiotherapy planning.

Rapid registration for wide field of view freehand three-dimensional ultrasound.

A freehand scanning protocol is the only way to acquire arbitrary large volumes of three-dimensional ultrasound (US) data. For some applications, multiple freehand sweeps are required to cover the area of interest. Aligning these multiple sweeps is difficult, typically requiring nonrigid image-based registration as well as the readings from the spatial locator attached to the US probe. Conventionally, nonrigid warps are achieved through general elastic spline deformations, which are expensive to compute and difficult to constrain. This paper presents an alternative registration technique, where the warp's degrees of freedom are carefully linked to the mechanics of the freehand scanning process. The technique is assessed through an extensive series of in vivo experiments, which reveal a registration precision of a few pixels with comparatively little computational load.

High-definition freehand 3-D ultrasound.

This paper describes a high-definition freehand 3-D ultrasound (US) system, with accuracy surpassing that of previously documented systems. 3-D point location accuracy within a US data set can be achieved to within 0.5 mm. Such accuracy is possible through a series of novel system-design and calibration techniques. The accuracy is quantified using a purpose-built tissue-mimicking phantom, designed to create realistic clinical conditions without compromising the accuracy of the measurement procedure. The paper includes a thorough discussion of the various ways of measuring system accuracy and their relative merits; and compares, in this context, all recently documented freehand 3-D US systems.

Sensorless freehand 3-D ultrasound using regression of the echo intensity.

In freehand 3-D ultrasound (US), a position sensor is attached to the probe of a 2-D US machine. The resulting 3-D data permit flexible visualisation and more accurate volume measurement than can be achieved using 2-D B-scans alone; however, the use of the position sensor can be inconvenient for the clinician. The objective is, thus, to replace the sensor with a technique for estimating the probe trajectory based on the B-scan images, themselves. One such technique exists, based on decorrelation algorithms. This paper presents an alternative approach based on linear regression of the echo-envelope intensity signal. A probabilistic analysis of the speckle characteristics of the US signal leads to a linear model, on which the regression algorithm is based. The gradient parameter of this model is shown to be directly related to probe motion. The viability of the new approach is demonstrated through simulations and in vitro and in vivo experiments.