Evaluation of semiautomated measurements of mesothelioma tumor thickness on CT scans

RATIONALE AND OBJECTIVES: To evaluate the clinical acceptability of semiautomated methods for the measurement of mesothelioma tumor thickness in computed tomography (CT) scans. MATERIALS AND METHODS: A computer interface was developed to allow the acquisition of semiautomated mesothelioma tumor thickness measurements, which require the manual selection of a point along the outer margin of the tumor in a CT section. After application of an automated lung segmentation method, the computer automatically identifies a corresponding point along the inner margin of the tumor (as represented by the lung boundary), constructs a line segment between the manually selected outer tumor margin point and the computer-determined inner tumor margin point, and computes tumor thickness as the length of this line segment. Three radiologists and oncologists independently reviewed line segments representing the semiautomated measurements generated by three different algorithms at 134 measurement sites in the CT scans of 22 mesothelioma patients. The observers either accepted a measurement line segment or modified it through the interface. Differences between the initial semiautomated measurements and the measurements as modified by the observers were analyzed. RESULTS: The frequency with which observers accepted the semiautomated measurements without modification was as high as 86%. Of all measurements across all observers and methods (1,206 measurements), 89% were changed by 2 mm or less. CONCLUSION: We have developed semiautomated methods to measure mesothelioma tumor thickness. The potential of these methods has been demonstrated through an observer study. We expect these methods to become important tools for the efficient quantification of tumor extent.     

Familiarisation to treadmill walking in unimpaired older people

We studied the amount of time required for treadmill familiarisation in older people and also whether familiarised treadmill walking could be generalised to overground walking. Sixteen healthy volunteers over 65 years of age walked on a level overground walkway and on a treadmill at the same speed for up to 15 min. A motion measurement system was used to measure the sagittal-plane kinematics of the knee and cadence during overground walking and after 0, 2, 4, 6, 8, 10, 12 and 14 min of treadmill walking. Older adults had not familiarised to the treadmill within 15 min as many participants continued to hold the treadmill's handrails and as reliability and absolute difference scores were still changing. Participants were most familiarised after 14 min on the treadmill. Furthermore, treadmill walking after 14 min was not closely related to overground walking in older adults, with measures on the treadmill only being able to predict knee angles during overground to within 8.0 degrees , or cadence to within 16.6 steps/min with 95% confidence. Treadmill walking in older adults after a single 15-min training session could not be generalised to overground walking.     

Early Results of Endovascular Treatment of the Thoracic Aorta Using the Valiant Endograft

Endovascular repair of the thoracic aorta has been adopted as the first-line therapy for much pathology. Initial results from the early-generation endografts have highlighted the potential of this technique. Newer-generation endografts have now been introduced into clinical practice and careful assessment of their performance should be mandatory. This study describes the initial experience with the Valiant endograft and makes comparisons with similar series documenting previous-generation endografts. Data were retrospectively collected on 180 patients treated with the Valiant endograft at seven European centers between March 2005 and October 2006. The patient cohort consisted of 66 patients with thoracic aneurysms, 22 with thoracoabdominal aneurysms, 19 with an acute aortic syndrome, 52 with aneurysmal degeneration of a chronic dissection, and 21 patients with traumatic aortic transection. The overall 30-day mortality for the series was 7.2%, with a stroke rate of 3.8% and a paraplegia rate of 3.3%. Subgroup analysis demonstrated that mortality differed significantly between different indications; thoracic aneurysms (6.1%), thoracoabdominal aneurysms (27.3%), acute aortic syndrome (10.5%), chronic dissections (1.9%), and acute transections (0%). Adjunctive surgical procedures were required in 63 patients, and 51% of patients had grafts deployed proximal to the left subclavian artery. Comparison with a series of earlier-generation grafts demonstrated a significant increase in complexity of procedure as assessed by graft implantation site, number of grafts and patient comorbidity. The data demonstrate acceptable results for a new-generation endograft in series of patients with diverse thoracic aortic pathology. Comparison of clinical outcomes between different endografts poses considerable challenges due to differing case complexity.     

Imaging the vertebral artery

Although conventional intraarterial digital subtraction angiography remains the gold standard method for imaging the vertebral artery, noninvasive modalities such as ultrasound, multislice computed tomographic angiography and magnetic resonance angiography are constantly improving and are playing an increasingly important role in diagnosing vertebral artery pathology in clinical practice. This paper reviews the current state of vertebral artery imaging from an evidence-based perspective. Normal anatomy, normal variants and a number of pathological entities such as vertebral atherosclerosis, arterial dissection, arteriovenous fistula, subclavian steal syndrome and vertebrobasilar dolichoectasia are discussed.     

Comparison of computed tomography and conventional radiology in the assessment of treatment response of lytic bony metastases in patients with carcinoma of the breast

Full skeletal survey, localised radiographs and computed tomography (CT) examinations were compared with clinical assessment in the evaluation of treatment response of bony metastases in 20 patients with carcinoma of the breast. Conventional radiology, skeletal survey and localised views compared poorly with clinical assessment agreeing in only 35% and 50% respectively. CT concurred with the clinical assessment in 65% of patients, particularly with respect to healing (86%). CT predicted the effect of treatment in six additional patients and this was confirmed on follow-up assessment. It is suggested that the use of skeletal surveys in monitoring treatment response is limited and that for critical evaluation of treatment CT should be the method of choice.     

Patient exposure and associated radiation risks from fluoroscopically guided vertebroplasty or kyphoplasty

PURPOSE: To derive normalized data for the estimation of effective, gonadal, and peak skin doses to patients undergoing vertebroplasty or kyphoplasty and to investigate the potential for cancer induction, genetic effects, and radiation-induced skin injury after such procedures. MATERIALS AND METHODS: Dose values normalized over dose-area product were determined for all radiosensitive organs and tissues by using a humanoid phantom and thermoluminescence dosimetry separately for anteroposterior and lateral projections. Measurements were obtained for treatments of the fifth, eighth, and 11th thoracic vertebrae and the first, third, and fifth lumbar vertebrae. Total fluoroscopy time and resultant dose-area product from each fluoroscopic exposure were monitored in 11 consecutive patients (seven women and four men) undergoing kyphoplasty. The age range of these patients was 41-78 years, and the mean age was 58 years. RESULTS: Mean total fluoroscopy time for kyphoplasty was 10.1 minutes +/- 2.2 (standard deviation). Mean effective dose to patients from kyphoplasty was 8.5-12.7 mSv, and mean gonadal dose was 0.04-16.4 mGy, depending on the level of the treated vertebra. Skin injuries after kyphoplasty are improbable if source-to-skin distance is 35 cm or more; however, such injuries may occur if the total fluoroscopy time per projection is extended and/or the source-to-skin distance is less than 35 cm during the procedure. CONCLUSION: Patient radiation exposure and associated risks from vertebroplasty or kyphoplasty may be considerable. Data obtained in the current study may be used to establish patient effective dose, gonadal dose, and entrance skin exposure, as well as associated risks, from these fluoroscopically guided surgical treatments of spinal disorders.     

Removal of potassium from tuberous root vegetables by leaching.

OBJECTIVES: To determine analytically the amount of potassium in raw tuberous root vegetables (TRV); to estimate the amount of potassium that can be leached from raw TRV by soaking in water; and to determine whether the duration of soaking and the cooking method selected affect potassium extraction. DESIGN: Fresh TRV (ie, fresh and sweet batata, cocomalanga, dasheen, eddo, black yam, white yam, yellow yam, yampi, malanga, red yautia, white yautia, and yuca) were obtained from an ethnic market. Five experimental conditions with variations in soak time and cooking method were applied. Potassium was extracted from the ash of dried samples. The potassium content of aqueous extractions was determined through atomic absorption spectrophotometry. RESULTS: Mean potassium content was highest in raw cocomalanga and lowest in raw dasheen. All of the raw TRV, except for dasheen, had a potassium content >200 mg (5.1 mEq)/100 g sample. Soaking was not effective in the leaching of significant amounts of potassium from most TRV. The double cooking (DC) method (ie, boil, rinse, boil again) leached more potassium from most TRV than did the normal cooking (NC) method (ie, boil), except with dasheen and yellow yam. More vegetables retained a potassium content >200 mg (5.1 mEq)/100 g following NC versus DC (92% versus 54%). CONCLUSIONS: The potassium content of raw TRV varied considerably, with most tubers retaining a moderate or high potassium content following the leaching procedures. However, this study showed that DC appears to be more effective than NC for leaching potassium from TRV.     

Pulmonary kinematics from tagged hyperpolarized helium‐3 MRI

Purpose:

To propose and test the feasibility of a novel method for quantifying 3D regional pulmonary kinematics from hyperpolarized helium‐3 tagged MRI in human subjects using a tailored image processing pipeline and a recently developed nonrigid registration framework.

Materials and Methods:

Following image acquisition, inspiratory and expiratory tagged ³He magnetic resonance (MR) images were preprocessed using various image filtering techniques to enhance the tag surfaces. Segmentation of the three orthogonal sets of tag planes in each lung produced distinct point‐set representations of the tag surfaces. Using these labeled point‐sets, deformation fields and corresponding strain maps were obtained via nonrigid point‐set registration. Kinematic analysis was performed on three volunteers.

Results:

Tag lines in inspiratory and expiratory images were coregistered producing a continuous 3D correspondence mapping. Average displacement and directional strains were calculated in three subjects in the inferior, mid, and superior portions of the right and left lungs. As expected, the predominant direction of displacements with expiration is from inferior to superior.

Conclusion:

Kinematic quantitation of pulmonary motion using tagged ³He MRI is feasible using the applied image preprocessing filtering techniques and nonrigid point‐set registration. Potential benefits from regional pulmonary kinematic quantitation include the facilitation of diagnosis and local assessment of disease progression. J. Magn. Reson. Imaging 2010;31:1236–1241. © 2010 Wiley‐Liss, Inc.     

An automated skills assessment framework for laparoscopic training tasks

Background

Various sensors and methods are used for evaluating trainees' skills in laparoscopic procedures. These methods are usually task‐specific and involve high costs or advanced setups.

Methods

In this paper, we propose a novel manoeuver representation feature space (MRFS) constructed by tracking the vanishing points of the edges of the graspers on the video sequence frames, acquired by the standard box trainer camera. This study aims to provide task‐agnostic classification of trainees in experts and novices using a single MRFS over two basic laparoscopic tasks.

Results

The system achieves an average of 96% correct classification ratio (CCR) when no information on the performed task is available and >98% CCR when the task is known, outperforming a recently proposed video‐based technique by >13%.

Conclusions

Robustness, extensibility and accurate task‐agnostic classification between novices and experts is achieved by utilizing advanced computer vision techniques and derived features from a novel MRFS.