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Biomedical subjects

J H Ellis

Publications and source records attributed to J H Ellis.

At least 73 records · Page 4Linked to original sources
PubMed1993

Signal-to-noise measures for magnetic resonance imagers.

The signal-to-noise ratio (SNR) in magnetic resonance imaging represents one of the system operating variables that must be determined both for evaluating the performance of different imaging protocols on a particular machine, and for monitoring machine performance as part of a routine quality control (QC) program. Utilizing a phantom and set of automated analysis programs currently under development, this study evaluated several ways of measuring image signal and noise and demonstrated the importance of utilizing measured voxel volumes as opposed to nominal volumes in the calculation of SNR. The NEMA proposed standard for SNR is compared with several other SNR measures and is recommended as the measure to be used in routine SNR reporting. The importance of utilizing other SNR measures in addition to the NEMA proposed standard for routine QC is discussed.

Magnetic Resonance Imaging↗
PubMed1993

Treatment of renal transplant ureteral complications by percutaneous techniques.

From January 1985 to October 1990, 487 adult renal transplantations were performed at our institution. Of 16 ureteral complications noted 15 were initially managed with percutaneous nephrostomy. Of the 8 complications that occurred during the last 2 years 5 resolved on percutaneous nephrostomy and stenting, or stenting with dilation alone. We conclude that percutaneous nephrostomy is indicated as an initial step in the diagnosis and treatment of urological transplant complications, and that it allows for nonoperative resolution of many of these complications.

Adult↗
PubMed1993

Acute renal obstruction: evaluation with intrarenal duplex Doppler and conventional US.

To evaluate duplex Doppler ultrasound (US) in acute renal obstruction, bilateral intrarenal Doppler US was performed in 23 patients with unilateral renal obstruction (proved by means of intravenous urography) of 36 hours duration or less. A mean renal resistive index (RI) was calculated for each obstructed and normal contralateral kidney and compared with findings on conventional US scans. The mean RI in the obstructed kidneys was elevated (.77 +/- .07 [standard deviation]) and was higher than the mean RI in the normal contralateral kidney (.60 +/- .04) (P < .001). RIs in the obstructed kidneys were as follows: .75 or greater in 15 kidneys, .70-.74 (mild RI elevation) in five kidneys (but > or = .10 higher than the RI in the normal contralateral kidney), and less than .70 in three kidneys (two of these three patients had pyelosinus extravasation and one patient had clinical obstruction for only 4-5 hours). RI elevation occurred before collecting-system dilatation in four patients (17%). RI elevation occurs by 6 hours of clinical acute renal obstruction and may precede pyelocaliectasis. Renal duplex Doppler US contributes useful clinical information, especially when US is the first modality used to evaluate acute renal colic.

Acute Disease↗
PubMed1993

Duodenal injuries caused by blunt abdominal trauma: value of CT in differentiating perforation from hematoma.

OBJECTIVE: Traumatic duodenal perforation requires emergent surgery, whereas duodenal hematoma can often be treated nonsurgically. We assessed the CT findings in patients with blunt duodenal trauma to determine if CT can be used to differentiate these two duodenal injuries. MATERIAL AND METHODS: Seven consecutive patients with blunt duodenal trauma (three with perforation, four with hematoma) who underwent CT as part of their initial diagnostic evaluation were included in the study. All three perforations and one of four hematomas were surgically proved. Diagnoses of duodenal hematoma in the other three patients were based on typical features on upper gastrointestinal studies and complete resolution of clinical findings after conservative treatment. The CT scans were retrospectively reviewed without knowledge of the specific type of duodenal injury, and the findings were correlated with the results of the gastrointestinal studies and surgical findings. RESULTS: CT showed extraluminal gas or extravasated oral contrast material or both in the right anterior pararenal space in all three patients with duodenal perforation and in none of the patients with duodenal hematoma. Thickening of the duodenal wall and fluid in the right anterior pararenal space were seen in both groups of patients. CONCLUSION: Although the number of patients in the study was small, the results suggest that CT may be useful in differentiating duodenal perforation from hematoma without perforation. Extraluminal gas or extravasated oral contrast material or both were seen in the right anterior pararenal space in all three patients who had perforation and in none of the patients who had hematoma alone.

Abdominal Injuries↗
PubMed1993

Assessment of internal ureteral stent patency in patients with pyelocaliectasis: value of renal duplex sonography.

OBJECTIVE: The purpose of this study was to evaluate duplex Doppler sonography in the assessment of internal ureteral stent patency. SUBJECTS AND METHODS: Thirty-three kidneys with pyelocaliectasis and an internal stent were studied with Doppler sonography and conventional sonography. Stent patency was proved by subsequent contrast-enhanced studies, direct inspection of the stent after removal, or clinical follow-up. RESULTS: The 11 kidneys with stent dysfunction had a significantly higher mean resistive index (0.78 +/- 0.08) than the 22 kidneys with patent stents (resistive index = 0.62 +/- 0.05) (p < .001). Eighty-two percent (9/11) of kidneys with occluded stents had elevated resistive indexes. The two occluded stents with normal resistive indexes were found in kidneys without significant obstruction before stent placement. Ninety-one percent (20/22) of patent stents were associated with a resistive index of less than 0.70. In the two cases of falsely elevated Doppler studies, the resistive index was obtained only 24-36 hr after placement of the stent; however, the resistive index was at least 10% less than that before stent placement. No significant correlation existed between degree of pyelocaliectasis shown on real-time sonography and stent status. CONCLUSION: In the presence of pyelocaliectasis after placement of an internal ureteral stent, intrarenal Doppler sonography can be used to accurately distinguish between patency and obstruction. Real-time sonographic findings (degree of pyelocaliectasis) are not useful in this clinical situation.

Adult↗
PubMed1993

Renal duplex Doppler sonography in asymptomatic women during pregnancy.

The purpose of this study was to establish the normal range of the renal RI in pregnant women. Maternal renal RIs were calculated in 61 asymptomatic pregnant patients with at least unilateral pyelocaliectasis. A mean RI was calculated for each kidney. Overall, the mean RI was 0.61 +/- 0.05. The renal RI was > or = 0.70 in 4% (5/121) of kidneys with no statistically significant difference between the mean right (0.62 +/- 0.06) and left (0.60 +/- 0.04) kidney RIs. There was no correlation between trimester of pregnancy or degree of pyelocaliectasis and RI.

Blood Flow Velocity↗
PubMed1992

Experimental analysis of T1 imaging with a single-scan, multiple-point, inversion-recovery technique.

Look and Locker's single-scan, multiple-point, T1 determination technique modified for imaging applications was evaluated experimentally for its accuracy and reliability with respect to the pulse sequence parameters, in particular, to the interpulse delay, tD, and the tip angle, alpha. T1 imaging experiments were performed with a 0.5-T imaging system on a phantom which consisted of an array of vials containing 2% agarose gels doped with various amount of Mn2+ using different combinations of the parameter set (tD, alpha). T1 results obtained with this technique were compared with those measured by a conventional inversion-recovery procedure using the same spectrometer. Strategic choice of pulse sequence parameters to minimize experimental errors and the criteria for these choices will be discussed.

Humans↗
PubMed1992

Magnetic resonance imaging during intracavitary gynecologic brachytherapy.

The cases of three patients, two with Stage III-B and one with Stage II-B carcinoma of the cervix, are cited to illustrate specific advantages of magnetic resonance (MR) imaging over computed tomography (CT) during intracavitary gynecologic brachytherapy. CT and MR were performed during the first of two intracavitary implants. To obtain artifact-free images with the intracavitary implant in place, a CT- and MR-compatible Fletcher system applicator was used. Although CT failed to differentiate the cervical tumor clearly from surrounding tissues, the area of pathology could be identified on MR by comparing the T1-weighted (T1W) and T2-weighted (T2W) images. Cervical tumors typically exhibit low-signal intensity on T1W and high-signal intensity on T2W scans, whereas paracervical soft tissues demonstrate high intensity on both T1W and T2W images. This contrast permits the size, location, and paracervical involvement of the tumor to be defined by MR. Multiplanar MR images obtained during the patients' intracavitary brachytherapy help demonstrate the actual anatomic relationship between the tumor and the applicator. Isodose distributions displayed on these images show that, in two cases, the tumor margin extended beyond the prescribed isodose line. Thus, MR may prove to be a clinically useful reference during intracavitary brachytherapy for ascertaining radiation dose to actual tumor volume.

Brachytherapy↗
PubMed1992

Intranasal midazolam as a sedative for children during laceration repair.

We performed a retrospective chart review to determine the onset, duration, safety, and clinical sedative effects of 0.2 to 0.5 mg/kg intranasal midazolam in young children during laceration repair. Of 408 children treated for lacerations during an 8-month period, 42 (10%) received intranasal midazolam. Documentation was adequate for detailed analysis in 40 cases. Data are reported as mean +/- standard deviation and the frequency with 95% confidence limit (CL) estimates. The mean age of the study population was 32 +/- 9 months (range 12 months to 6 years), and the mean body mass was 14.5 +/- 3 kg. Topical or injected local anesthesia was used in 37 cases. Overall, 73% (CL 56% to 85%) of the children achieved adequate sedation. However, those receiving 0.2 to 0.29 mg/kg had adequate sedation in only 27% (CL 6% to 60%) of the cases compared with 80% (CL 52% to 95%) and 100% (CL 79% to 100%) when 0.3 to 0.39 and 0.4 to 0.5 mg/kg respectively were administered. When achieved, sedation occurred within 12 +/- 4 minutes, recovery occurred at 41 +/- 9 minutes, and discharge occurred at 56 +/- 11 minutes. No vomiting or clinically significant oxygen desaturation (defined as a drop of > 4% or to < 91%) was observed. We conclude that intranasal midazolam is a safe and effective sedative for laceration repair under local anesthesia in preschool-aged children. We recommend a dose of 0.3 to 0.5 mg/kg, with treatment failure less likely after 0.4 to 0.5 mg/kg compared with less than 0.3 mg/kg.

Administration, Intranasal↗
PubMed1992

Renal dysfunction in hepatic disease: early identification with renal duplex Doppler US in patients who undergo liver transplantation.

To improve early detection of renal dysfunction in patients who undergo liver transplantation, a prospective study was performed with intrarenal duplex Doppler sonography before and after liver transplantation in 42 patients. The duplex Doppler findings were compared with multiple clinical and laboratory findings; patients were grouped on the basis of preoperative renal resistive index (RI) and serum creatinine level. The mean initial renal RI was elevated (.73 +/- .07 [standard deviation]); after transplantation, it was lower (.60 +/- .06) (P less than .001). Thirty-six patients had a normal serum creatinine level at the preoperative Doppler examination. Patients with an elevated renal RI (n = 19) had a greater chance of subsequent renal dysfunction (P less than .001), hemodialysis (P less than .01), longer stays in the intensive care unit (P less than .05), and longer hospital stays after surgery (P less than .05) than those with a normal renal RI (n = 17). In 34 patients the RI fell 10% or more after surgery and none died, whereas five of eight patients (62%) whose RI fell less than 10% died. Doppler analysis enabled identification of patients without azotemia whose course of disease before and after surgery was similar to that of patients with clinically recognized renal disease.

Adolescent↗
PubMed1992

Superelastic guide-wire snare for removal of foreign bodies from the urinary tract.

A superelastic guide wire was used (after failure of other methods) as a loop snare to retrieve a foreign body from the ureter in three patients. In vitro comparison of the expansion capability of the superelastic guide wire and that of the standard retrieval wire showed that the superelastic wire forms larger loops within an elastic space. Also, because of less frictional resistance and its ability to be formed into stiffer loops, the superelastic wire resists kinking and is easier to manipulate than the standard wire.

Aged↗
PubMed1992

Complications of continuous ambulatory peritoneal dialysis: evaluation with CT peritoneography.

OBJECTIVE: Patients on continuous ambulatory peritoneal dialysis are frequently referred for radiologic evaluation of complications related to the dialysis. We studied the value of CT peritoneography in evaluating these complications. CT peritoneography is a technique in which CT scans are obtained after dialysis fluid containing iodinated contrast material is infused into the peritoneal cavity through the dialysis catheter. MATERIALS AND METHODS: Sixty consecutive CT studies performed on 48 patients during a 5-year period were retrospectively analyzed. In each case (with two exceptions), the patient had clinical findings suggesting a complication related to peritoneal dialysis. Each study was reviewed for evidence of dialysate leaks, hernias, unopacified fluid collections, and peritoneal adhesions. The patients' medical records also were reviewed to determine the resulting therapy and outcome. RESULTS: Twenty-nine dialysate leaks were detected on 25 examinations: 15 were along the catheter tunnel, 10 were at the site of a previous surgical incision, two were at a previous catheter site, and two were from an undetermined site (catheter tunnel suspected in both cases). Loculated, unopacified peritoneal fluid collections were present on seven examinations. Adhesions limiting dialysate distribution were shown on five examinations. Five abdominal wall hernias and two inguinal hernias were detected. Overall, at least one abnormality related to continuous ambulatory peritoneal dialysis was shown on 40 (67%) of 60 studies. In 29 (73%) of these cases, clinical management was changed. CONCLUSION: CT peritoneography is useful for evaluating complications commonly encountered in patients on continuous ambulatory peritoneal dialysis.

Adult↗
PubMed1991

Calretinin and calbindin in the retina of the developing chick.

Calretinin and calbindin-D28k are two calcium-binding proteins that are present in largely different sets of nerve cells in the central nervous system. Their appearance during development of the chick retina was studied by immunohistochemistry and Western blots. The patterns are mature one day before hatching. Each cell type acquires its characteristic calcium-binding protein several days after its differentiation has started, but in most cases before morphological maturation is complete. There is also an early phase of calbindin immunoreactivity in many immature amacrine cells, and of calretinin immunoreactivity in the presumptive photoreceptor layer, suggesting that these proteins may have distinct functions in differentiating cells.

Animals↗
PubMed1991

Staging relationships and outcome in early stage testicular cancer: a report from the Testicular Cancer Intergroup Study.

The Testicular Cancer Center Intergroup Study entered surgically staged patients with nonseminomatous tumor and metastases limited to the regional lymph nodes into a previously reported cooperative trial of immediate versus delayed therapy for positive retroperitoneal node disease. Patients with negative nodes (stage I) were placed in an observation registry with specified treatment strategy upon relapse. Of 264 stage I cancer patients 27 (10.2%) had recurrence: 5 of these 27 patients died after recurrence of the testicular malignancies, while 4 other nontumor-related deaths have occurred. Pre-lymphadenectomy staging characteristics observed to predict significantly node positivity are the results of radiological examinations, presence of tumor invasion, vascular invasion and tumor histology. In a multiple logistic regression analysis with these variables, misclassification still occurs in more than a fourth of the patients. Future refinements in diagnosis may allow for better prediction of these patients at risk to have positive lymph nodes and ultimately recurrence. Presently, if assessment of nodal involvement is the objective, noninvasive procedures are not an adequate substitute for surgical staging with modified lymphadenectomy.

Adult↗
PubMed1991

Diagnostic usefulness of post-void film in intravenous urogram.

A survey was sent to urologists to assess their subjective evaluation of the post-void film in the intravenous urogram (IVU). Most of the urologists believed that the post-void film should be a routine part of all IVUs, particularly in men over forty years of age, and estimated that the film contributed useful information in 30 percent of cases. One hundred fifty IVUs were reviewed to assess the actual value of the post-void film in 119 different patients. In these patients, the postvoid film was seen to give unique information not available by history or films of the filled bladder in only 3 percent of the cases. Therefore, we conclude the post-void film should not be a routine part of every IVU, and should be obtained on an as-needed basis only.

Adult↗
PubMed1991

Sarcoidosis: abdominal manifestations at CT.

There are few data in the literature on the abdominal manifestations of sarcoidosis at computed tomography (CT). To determine whether differences in nodal distribution and appearance can be reliably used to distinguish between sarcoidosis and non-Hodgkin lymphoma (NHL), the authors retrospectively reviewed the abdominal and pelvic CT scans of 16 patients with biopsy-proved sarcoidosis and 20 patients with biopsy-proved NHL. Eleven of the 16 patients with sarcoidosis had abdominal and/or pelvic lymphadenopathy, which was common at all nodal sites except for the retrocrural and pelvic locations. There was a statistically significant lower frequency of retrocrual adenopathy in sarcoidosis than in NHL. Mean nodal size was significantly greater in NHL. Nodes tended to be confluent in NHL and discrete in sarcoidosis. Hepatomegaly was seen in six of the 16 patients (38%) with sarcoidosis and splenomegaly was present in nine of 15 (60%). CT depicted hepatic lesions in only three of eight patients (38%) with biopsy-proved hepatic involvement. Splenic lesions were seen at CT in five of the 15 patients (33%). The authors believe that the overlap in nodal appearance and distribution poses a limitation for use of these criteria in accurate disease characterization.

Diagnosis, Differential↗
PubMed1991

Acute renal failure: possible role of duplex Doppler US in distinction between acute prerenal failure and acute tubular necrosis.

Ultrasonography (US) of the native kidneys is commonly requested for acute renal failure (ARF), although in most cases the examination results are negative. To detect changes in the Doppler waveform associated with ARF and determine whether Doppler US can provide significant diagnostic information not available with standard US, 91 patients with ARF were studied to determine a mean resistive index (RI) for each patient. Forty-six patients had acute tubular necrosis (ATN) with a mean RI +/- 1 standard deviation of .85 +/- .06, which was significantly higher than the mean RI of .67 +/- .09 in 30 patients with prerenal ARF (P less than .01). Fifteen patients had ARF due to non-ATN intrinsic renal disease (mean RI, .74 +/- .13). An elevated RI (greater than or equal to .75) occurred in 91% of patients with ATN versus only 20% of patients with prerenal azotemia. Patients with severe liver disease (hepatorenal syndrome) are a subset of those with prerenal ARF that accounted for most of the elevated RIs in this group. The study demonstrates that intrarenal Doppler US allows detection of changes associated with ARF far more often than standard US. More important, Doppler US may be helpful in distinguishing ATN from prerenal azotemia.

Acute Kidney Injury↗