Customized Tool for the Validation of Optical Coherence Tomography in Differentiation of Prostate Cancer.

OBJECTIVE: To design and demonstrate a customized tool to generate histologic sections of the prostate that directly correlate with needle-based optical coherence tomography pullback measurements. MATERIALS AND METHODS: A customized tool was created to hold the prostatectomy specimens during optical coherence tomography measurements and formalin fixation. Using the tool, the prostate could be sliced into slices of 4 mm thickness through the optical coherence tomography measurement trajectory. In this way, whole-mount pathology slides were produced in exactly the same location as the optical coherence tomography measurements were performed. Full 3-dimensional optical coherence tomography pullbacks were fused with the histopathology slides using the 3-dimensional imaging software AMIRA, and images were compared. RESULTS: A radical prostatectomy was performed in a patient (age: 68 years, prostate-specific antigen: 6.0 ng/mL) with Gleason score 3 + 4 = 7 in 2/5 biopsy cores on the left side (15%) and Gleason score 3 + 4 = 7 in 1/5 biopsy cores on the right side (5%). Histopathology after radical prostatectomy showed an anterior located pT2cNx adenocarcinoma (Gleason score 3 + 4 = 7). Histopathological prostate slides were produced using the customized tool for optical coherence tomography measurements, fixation, and slicing of the prostate specimens. These slides correlated exactly with the optical coherence tomography images. Various structures, for example, Gleason 3 + 4 prostate cancer, stroma, healthy glands, and cystic atrophy with septae, could be identified both on optical coherence tomography and on the histopathological prostate slides. CONCLUSION: We successfully designed and applied a customized tool to process radical prostatectomy specimens to improve the coregistration of whole mount histology sections to fresh tissue optical coherence tomography pullback measurements. This technique will be crucial in validating the results of optical coherence tomography imaging studies with histology and can easily be applied in other solid tissues as well, for example, lung, kidney, breast, and liver. This will help improve the efficacy of optical coherence tomography in cancer detection and staging in solid organs.

Computer-assisted planning and navigation for corrective distal radius osteotomy, based on pre- and intraoperative imaging.

Malunion after a distal radius fracture is very common and if symptomatic, is treated with a so-called corrective osteotomy. In a traditional distal radius osteotomy, the radius is cut at the fracture site and a wedge is inserted in the osteotomy gap to correct the distal radius pose. The standard procedure uses two orthogonal radiographs to estimate the two inclination angles and the dimensions of the wedge to be inserted into the osteotomy gap. However, optimal correction in 3-Dspace requires restoring three angles and three displacements. This paper introduces a new technique that uses preoperative planning based on 3-D images. Intraoperative 3-D imaging is also used after inserting pins with marker tools in the proximal and distal part of the radius and before the osteotomy. Positioning tools are developed to correct the distal radius pose in six degrees of freedom by navigating the pins. The method is accurate ( d 1.2 mm, ϕ 0.9°, m TRE = 1.7 mm), highly reproducible (SE (d) < 1.0 mm, SE (ϕ) ≤ 1.4°, SE (m) (TRE) = 0.7 mm), and allows intraoperative evaluation of the end result. Small incisions for pin placement and for the osteotomy render the method minimally invasive.

An instrumented, dynamic test for anterior laxity of the ankle joint complex.

Evaluation of anterior laxity of the ankle joint complex is a difficult clinical problem. Currently, the prime determinant for anterolateral ligament function is the subjective manual examination of anterior laxity of the ankle joint complex. An instrumented dynamic test was developed for objective measurement of anterior laxity of the ankle joint complex. The principle of the test was to apply a force-impulse to the calcaneus, within the muscle reflex time, and to measure anterior-posterior and mediolateral rotation. The test was performed on a cadaver specimen and on 15 volunteers of which five subjects suffered from chronic one-sided lateral ankle ligament instability. In the cadaver test, anterior translation values increased from 5 to 11 mm, after cutting the anterior talofibular ligament and subsequently cutting the calcaneofibular ligament. In the 10 normal subjects, the mean anterior translation value was 6.7 mm (+/-1.9 mm). The relative variation of the test result within a measurement session was 2.5% (+/-1.6%). Between the sessions the relative laxity variation was 2.6% (+/-2.6%). In the ten normal subjects the mean right-left difference was not significantly different from zero. In four out of the five patients it was more than 2mm. As in the cadaver test in all measurements, the mediolateral rotations were small (<2.5 degrees ). The volunteers complained about same pain at the heel after multiple test sessions. In conclusion the dynamic, functional test appears to be capable of objectively measuring a value for anterior laxity of the ankle joint complex reflecting the functional status of the anterolateral ankle ligaments.

A new transducer system for direct motor unit force measurement.

A new transducer was developed for in situ measurement of the force vector in a complex muscle. The transducer measures the magnitude, and the line of action of a force in a single plane. The dynamic range of the transducer is 0-5 N. This range includes the small forces developed by an active motor unit and the relatively large passive force of a whole muscle. In this study we present the details of the transducer design and specifications, and describe its application in the measurement of motor unit forces of the rabbit masseter muscle.

Respiratory valve for oxygen uptake measurements during swimming.

A detailed description of a respiratory valve to measure oxygen uptake while swimming is given. The effect on body drag of the addition of this equipment was measured in four subjects swimming over a range of speeds (0.9-1.9 m s-1). The respiratory valve has a low airflow resistance (29 Pa at an airflow of 8 l X s-1) and a small deadspace (30 ml). Total body drag when swimming while wearing the respiratory equipment did not differ significantly from that when swimming without the equipment. It is concluded that this respiratory valve is ideal for making valid and reliable measurements of oxygen uptake during swimming.

Measurement of active drag during crawl arm stroke swimming.

In order to measure active drag during front crawl swimming a system has been designed, built and tested. A tube (23 m long) with grips is fixed under the water surface and the swimmer crawls on this. At one end of the tube, a force transducer is attached to the wall of the swimming pool. It measures the momentary effective propulsive forces of the hands. During the measurements the subjects' legs are fixed together and supported by a buoy. After filtering and digitizing the electrical force signal, the mean propulsive force over one lane at constant speeds (ranging from about 1 to 2 m s-1) was calculated. The regression equation of the force on the speed turned out to be almost quadratic. At a mean speed of 1.55 m s-1 the mean force was 66.3 N. The accuracy of this force measured on one subject at different days was 4.1 N. The observed force, which is equal to the mean drag force, fits remarkably well with passive drag force values as well as with values calculated for propulsive forces during actual swimming reported in the literature. The use of the system does not interfere to any large extent with normal front crawl swimming; this conclusion is based on results of observations of film by skilled swim coaches. It was concluded that the system provides a good method of studying active drag and its relation to anthropometric variables and swimming technique.

A portable lightweight Douglas bag instrument for use during various types of exercise.

A construction outline of lightweight portable equipment for VO2 measurements by the Douglas bag method is given. The equipment consists of three separate units: an inspiration-expiration valve, a switch directing the expiratory flow, and a disconnectable bag with stopcock. The ease of operation assures good reproducibility of the results. Experiences during maximal speed skating are described. Use of the equipment demands only simple operations by the subject, which do not interfere with the exercise.

Implantable stimulating electrode for baroreceptor afferent nerves in rabbits.

An implantable stimulating electrode was developed for baroreceptor afferent nerves in the freely moving rabbit (nerve diam 0.1-0.2 mm). It consists of highly flexible electrode leads (coiled Pt-Ir wire) and silicone rubber (Silastic) as insulation. The electrodes were shown to be effective for up to 245 days after implantation in the neck. Electrode failure was due to dislodgment of the electrode (early failures) or (ultimately) cable breakage. Heart rate and blood pressure responses of separate and combined stimulation of depressor and carotid sinus nerves are shown. In vitro studies demonstrated some current leakage from the electrode to surrounding tissues, but the in vivo measurements show the validity of the method.

A mechanical oscilloscope for vision research.

A "mechanical oscilloscope" is described in which a lightbeam (Z-axis) is projected via a single front aluminized moving mirror. The mirror is mounted in a suspension frame allowing the simultaneous rotation about two mutually perpendicular axes. The linear displacements of two loudspeaker-coils are transformed mechanically into mirror rotations and an electronic position/velocity feedback control system is used to drive the loudspeakers. The bandwidth of the resulting X- and Y-axis deflection systems is of the order of 100-200 Hz. The flexibility of Z-axis control (colour, pattern, intensity, etc.) makes this instrument an attractive component of light stimulation systems for psychophysical or electrophysiological studies of vision.