Biomedical subjects
Publications and source records attributed to M L Skolnick.
A system utilizing a multi-image capacity video disc recorder rather than a photographic camera for the initial recording of ultrasound images id described, as well as the resulting benefits.
Passavant's ridge was studied in 43 patients via multiview videofluoroscopy incorporating the simultaneous recording of speech. Ratings of the videotapes were made at full speed, in slowmotion, and by stop-framing. The following results were found: (1) Just as there are variable patterns of velopharyngeal closure, there were also variations in the way in which Passavant's ridge is positioned relative to the velum, and in the ridge's subsequent role in velopharyngeal narrowing or closure. (2) The ridge was the primary pharyngeal structure at the level of the velum that closed or locally narrowed the velopharyngeal portal in 37% of patients. (3) Passavant's ridge usually appeared as a structure encompassing both the lateral and posterior pharyngeal walls, and its presence was usually associated with active lateral pharyngeal wall motion. (4) Passavant's ridge was more prominent when the head was in the hyper-extended rather than the neutral position. (5) Passavant's ridge moved in a highly consistent manner, synchronous with velar movement.
In patients clinically suspected of possessing intra-abdominal abscesses, ultrasonic imaging is an effective way of detecting suspicious localized fluid collections. However, definitive diagnosis depends upon sampling the fluid collections, which can be most easily performed by percutaneous fine needle aspiration of the collection under ultrasonic guidance. Sixty-six patients suspected of having intra-abdominal abscesses had localized fluid collections demonstrated by ultrasonic scanning. The composition of the fluid was proved in 40 patients by percutaneous aspiration; in 26, by surgical drainage alone, and in 30, by both methods. The aspiration procedure is relatively painless, rapid and free of complications.
Twenty-six cases of ultrasonically guided percutaneous fine-needle aspiration biopsies of abdominal masses are reported. Included are masses in the pancreas, retroperitoneum, liver, kidney, and pelvis. Aspiration biopsies accurately diagnosed or excluded malignancy in 21 patients (81%). The procedure, performed under local anesthesia, is rapid, simple and almost painless. No complications occurred; specifically, there was no hemorrhage, peritonitis, or spread of tumor along the needle tract.
In order to improve the visualization of kidneys in patients who are scanned prone, a compression pillow is placed under the anterior abdomen at the approximate level of the kidneys. We hypothesize that the improved imaging occurs because the compression reduces the thickness of soft tissues overlying the kidneys and, therefore, lessens the amount of attenuation, scattering, and absorption the ultrasound beam undergoes. The benefits of this technique are illustrated in a patient with a renal cyst.
This paper describes a new real-time servo controlled sector scanner that produces high resolution images and has functionally programmable features similar to phased array systems, but possesses the simplicity of design and low cost best achievable in a mechanical sector scanner. The unique feature is the transducer head which contains a single moving part--the transducer--enclosed within a light-weight, hand held, and vibration free case. The frame rate, sector width, stop action angle, are all operator programmable. The frame rate can be varied from 12 to 30 frames s-1 and the sector width from 0 degrees to 60 degrees. Conversion from sector to time motion (T/M) modes are instant and two options are available, a freeze position high density T/M and a low density T/M obtainable simultaneously during sector visualization. Unusual electronic features are: automatic gain control, electronic recording of images on video tape in rf format, and ability to post-process images during video playback to extract T/M display and to change time gain control (tgc) and image size.
This paper describes a new real-time servo-controlled sector scanner that produces high-resolution images similar to phased-array systems, but possesses the simplicity of design and low cost best achievable in a mechanical sector scanner. Its unique feature is the transducer head which contains a single moving part--the transducer. Frame rates vary from 0 to 30 degrees and the sector angle from 0 to 60 degrees. Abdominal applications include: differentiation of vascular structures, detection of small masses, imaging of diagonally oriented organs. Survey scanning, and demonstration of regions difficult to image with contact scanners. Cardiac uses are also described.
Guided by ultrasound percutaneous antegrade pyelography can be accomplished with great ease in patients with obstructive hydronephrosis. The exact location and the depth of the dilated renal pelvis can be determined accurately with the use of ultrasound and the procedure is similar to that of a cyst puncture. Antegrade pyelography provides significant diagnostic information on the nature of the obstructive lesion and can be performed as an adjunct to a retrograde study or as an alternative to a retrograde pyelogram. Ultrasound is considered a most advantageous aid to the performance of antegrade pyelography.
Continuous raster scanning can improve abdominal B scan image resolution and decrease the time required for scanning. Rapid, serial, single-sweep scans are performed at 3 to 8 mm intervals during suspended respiration. This technique markedly reduces organ distortion by respiratory and vascular motion. It is best performed with a contact scanner operating in video mode that utilizes a high resolution store oscilloscope.
A grey-scale display system for ultrasound contact B-scanning has been developed that produces six shades of grey on a high resolution storage oscilloscope. The grey shades are displayed by varying the density distribution of dots of a constant intensity. The system design and clinical results are presented. Advantages of our system are: 1. the non-degraded image is immediately displayed as the scan is performed. 2. the writing speed is faster than most scan converter tube systems son that many closely spaced scans can be rapidly performed in order to improve visualization of small anatomic structures, and 3. images comparable to those of scan converter display systems are produced at a significantly lower equipment cost.
Five patients evaluated via multi-view videofluoroscopy were found to have incongruous movements between the velum and lateral aspects of the pharyngeal walls. All five patients had velopharyngeal insufficiency resulting from either absent lateral pharyngeal wall motion in the presence of velar mobility or absent velar mobility in the presence of lateral pharyngeal wall motion. The data indicates that these valving patterns are not rare phenomena of velopharyngeal valving. Treatment by pharyngeal flap or other methods for velopharyngeal insufficiency must be suited to these peculiar valving patterns based on adequate diagnostic information.
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This paper discusses the differential diagnosis of renal cystic masses with non-grey scale ultra-sound scanners, and presents some limitations of the equipment. Included among cystic masses are serous cysts, hemorrhagic cysts, calcified cysts, hydronephrosis, abscesses, and necrotic tumors. Technical aspects of scanning of very important. Only single sweep scans are performed, usually as a series of closely spaced scans during suspended respiration. Breathing during scanning, and compound scanning, degrade image sharpness and can completely obscure small cysts. Serous cysts and hydronephrosis usually present distinct and different ultrasonic appearances. Necrotic tumors, hemorrhagic cysts, and abscesses can not be differentiated. Cysts with calcified walls can not be identified as cystic masses because the calcium within the wall prevents sound from penetrating through the mass. To confirm the diagnosis of a renal cystic mass, percutaneous puncture under ultrasonic guidance can be performed. Fluid is removed for laboratory studies and radio-opaque contrast material is instilled within the cavity. X-rays are then to better define the contours and internal architecture.
Visualization of the normal upper abdominal vessels has been reported using gray scale ultrasound contact scanners. In this report we will demonstrate that the same vessels can also be seen on scans made with bistable equipment. The vessels on serial sagittal and transverse ultrasound scans will be compared with arteriograms, anatomic drawings, and cadaver photographs to provide the anatomic justification for identifying the vessels seen on the ultrasound images. Modifications in scanning technique and equipment setting to obtain the bistable images of vessels are discussed.
Construction and operation of a simple and inexpensive water bath adapting a contact B-scanner for thyroid and testicular imaging is described. The device consists of two parts: a water bath with supporting frame, and a bead chain arrangement attached to the scanner arm to maintain the transducer at a constant height above the skin during scanning.
Numerous artifacts can occur during contact B scanning of the abdomen. These artifacts may give anatomically inaccurate scans and thus lead the interpreter into making an inaccurate diagnosis. This paper describes and illustrates artifacts resulting from improper scanning techniques, improperly set gain levels, motion related organ distortion, and acoustic reverberations.
A new therapeutic technique for the treatment of velopharyngeal incompetence during speech was administered to four subjects ranging in age from four to 19 years. The technique is an operant procedure designed to utilize successive approximation to competent speech via competent blowing or whistling closure mechanisms. The technique is based on cinefluoroscopic observations of normals utilizing the same closure mechanism for speech, blowing and whistling plus videofluoroscopic observations of cleft-palate subjects who were capable of attaining normal closure patterns for blowing and whistling, but not for speech. It is speculated that speech incompetence in individuals who can achieve closure during blowing and whistling is a result of an error in learning.
The frontal and lateral cinefluorographic views of five normal subjects performing speech, blowing, and whistling tasks were synchronized in order to observe where the greatest degree of medial movement in the lateral aspects of the pharyngeal walls was occurring in relation to structures observed in lateral view. The results of the synchronization procedure indicates that for all five subjects, maximum medial excursion in the lateral walls of the pharynx occurred at the level of the full length of the velum and hard palate, well below the levator eminance. It is hypothesized that this observed interaction may be due to the select contraction of those fibers of the superior constrictor muscle which enter the velum via the lateral walls and those fibers attached to the pterygoid plates as well as levator muscle activity. It is also suggested that definitive physiological data must be obtained from further study of combined EMG and fluoroscopic procedures.