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Biomedical subjects

J P McGahan

Publications and source records attributed to J P McGahan.

At least 19 recordsLinked to original sources
PubMed2005

Pelvic free fluid: clinical importance for reproductive age women with blunt abdominal trauma.

OBJECTIVE: To evaluate the importance of isolated pelvic free fluid (FF) detected by ultrasound examination in pregnant patients and in non-pregnant reproductive age women with blunt abdominal trauma (BAT). METHODS: Reproductive age women aged 10-50 years who presented with BAT and underwent focused abdominal sonography for trauma (FAST) from January 1995 to June 2002 at a Level 1 trauma center were included. Patients were assigned to four groups according to the location of FF detected by ultrasound (Group 1, no FF; Group 2, FF in pelvis; Group 3, FF in abdomen; Group 4, FF in abdomen and pelvis). Ultrasound findings were compared with intra-abdominal and pelvic injuries detected by computed tomography and/or laparotomy. Pair-wise comparison was performed using a Fisher's exact test. RESULTS: Ultrasound detection of FF in the abdomen alone or FF in the abdomen and pelvis was significantly associated with intra-abdominal injury (IAI) compared to those without FF (P < 0.001) for both pregnant and non-pregnant reproductive age women. FF isolated to the pelvis was also associated with a higher injury rate compared to no FF in pregnant women (30% vs. 3%, P = 0.005) and in non-pregnant reproductive age women (39.5% vs. 3.7%, P < 0.001). CONCLUSIONS: In reproductive age women with BAT, ultrasound detection of FF in the abdomen alone, in both the abdomen and pelvis, or isolated to the pelvis is associated with a higher IAI rate. Therefore, isolated FF in the pelvis should not necessarily be considered physiological in pregnant and non-pregnant patients with BAT.

Abdominal Injuries↗
PubMed2004

Normal organ volume assessment from abdominal CT.

We determined the normal distribution of abdominal organ volumes measured from abdominal computed tomographic (CT) images. A total of 149 adult abdominal CT studies were selected, and 711 organs (388 from males, 323 from females) were outlined by hand on each CT image by using a computer. More than 18000 organ outlines were traced. The organs studied included left and right kidneys, left and right adrenals, spleen, pancreas, and liver, and the first lumbar vertebrae was also evaluated. Using the known pixel size and section thickness, organ volumes were computed. Organ volumes were corrected for height and weight for each sex. The normal and cumulative normal distributions for each organ studied were computed, demonstrating the range of organ volumes for each sex that exist in the normal adult population. Organ volumes ranged from a mean of 4.4 mL (female left adrenal) to 1710 mL (male liver). Mean organ volumes were 64.4, 156.5, 179.8, and 1411 mL for the female pancreas, kidneys, spleen, and liver, respectively. Corresponding male volumes were 87.4, 193.1, 238.4, and 1710 mL, respectively. Tabular data are provided that indicate the relative size for each organ volume in terms of the cumulative probability distribution. Normative data are provided to allow physicians to estimate where in the normal range a particular organ volume lays. Organ volumes may be useful as quantitative indices of pathologic conditions.

Abdomen↗
PubMed2001

Ultrasound detection of blunt splenic injury.

The purpose of this study was to determine the sensitivity of emergency ultrasound (US) for the detection of blunt splenic injury (BSI), and to describe sonographic parenchymal patterns. Over 3 years, 2138 emergency US were performed, and 162 patients had BSI. CT was performed for 76 patients, and there were 86 laparotomies. Seventy patients (43%) had concomitant intraabdominal injuries. Ultrasound detected free fluid in 109 patients (67%), and parenchymal injury in 31 patients (19%). There were 48 false negative US (30%). Sonographic patterns included a diffuse heterogeneous appearance, hyperechoic and hypoechoic perisplenic crescents, and discrete hypoechoic or hyperechoic areas within the spleen. Overall sensitivity of US for detection of BSI was 69%, but was 86% for grade III or higher injuries. Ultrasound is most sensitive for the detection of grade III or higher BSI based on the presence of haemoperitoneum. Ultrasound may also identify BSI on the basis of parenchymal abnormality, with a diffuse heterogeneous pattern most commonly encountered. Sonographic evaluation for both free fluid and parenchymal injury improves sensitivity of US.

Adolescent↗
PubMed2001

From the RSNA refresher courses: focused abdominal US for trauma.

Focused abdominal ultrasonography (US) has been introduced in Europe as a method to evaluate blunt abdominal trauma. The main focus of the examination is detection of free fluid in the abdomen secondary to injury of the abdominal organs. The examination takes only a few minutes to perform. In the authors' experience, trauma patients in unstable condition and in whom significant free fluid is detected are immediately taken to the operating room for surgical exploration without undergoing computed tomographic (CT) correlation. The authors have also used US to identify the specific site of organ injury. Injuries to solid organs such as the liver, spleen, and kidney that are identified with US usually appear heterogeneous or hyperechoic. A hematoma surrounding the injured organ may appear echogenic or hypoechoic. However, pitfalls of focused abdominal US for trauma include failure to show contained solid-organ injuries; injuries to the diaphragm, pancreas, and adrenal gland; and some bowel injuries. Thus, negative findings at US do not exclude an intraperitoneal injury, and close clinical observation or CT is warranted.

Abdominal Injuries↗
PubMed2001

Ultrasonographic evaluation of diaphragmatic motion.

OBJECTIVE: To evaluate the technical feasibility and utility of ultrasonography in the study of diaphragmatic motion at our institution. METHODS: The study consisted of 2 parts. For part I, in 23 volunteers we performed 23 studies on 46 hemidiaphragms with excursions documented on M-mode ultrasonography For part II, in 22 patients we performed 52 studies in 102 hemidiaphragms. In 50 studies both hemidiaphragms were studied, and in another 2 studies only 1 hemidiaphragm was studied. Patients' ages ranged from birth to 66 years (mean, 23 years). There were 16 male and 6 female patients. Indications for the study were (1) suggestion of paralysis of the diaphragm (n = 22); (2) if the diaphragm was already known to be paralyzed, for evaluation of response to phrenic nerve or pacer stimulation (n = 9); and (3) follow-up of previous findings (n = 21). Patients were examined in the supine position in the longitudinal semicoronal plane from a subcostal or low intercostal approach. Motion was documented with real-time ultrasonography and measured with M-mode ultrasonography. RESULTS: Of the 102 clinical hemidiaphragms studied, findings included normal motion (n = 42), decreased motion (n = 22), no motion (n = 6), paradoxical motion (n = 10), positive pacer response (n = 13), negative pacer response (n = 2), positive phrenic stimulation (n = 6), and negative phrenic stimulation (n = 1). There were no failures of visualization. CONCLUSIONS: Ultrasonography proved feasible and useful in evaluating diaphragmatic motion. In our practice it has replaced fluoroscopy. Ultrasonography has advantages over traditional fluoroscopy, including portability, lack of ionizing radiation, visualization of structures of the thoracic bases and upper abdomen, and the ability to quantify diaphragmatic motion.

Adolescent↗
PubMed2000

The role of percutaneous biopsy in detection of pancreatic transplant rejection.

The purpose of this study was to investigate the effectiveness and safety of percutaneous pancreatic transplant biopsy guided by ultrasound alone or with a combination of computerized tomography (CT) for pancreas localization and ultrasound for needle placement. We also compare our finding on the use of 18-gauge and 20-gauge needles for percutaneous pancreatic transplant biopsy. In 42 attempted biopsies performed on 21 patients, two different imaging modalities were used. Twenty-seven attempted biopsies were performed under the guidance of ultrasound alone, and 15 used a combination of ultrasound and CT. Of the 27 ultrasound-guided biopsies. 24 produced at least one sample adequate for histopathological analysis for an 89% biopsy success rate. Of the 15 biopsies guided by combined ultrasound and CT, 11 produced adequate samples for a 73% success rate. For all biopsies, an 83% success rate was found. In assessing the use of 18-gauge versus 20-gauge needles, 86 out of 110 tissue cores were adequate for histopathological analysis for a 78% yield. In 27 biopsy attempts using the 18-gauge needle, 75 tissue cores were obtained, for an average of 2.8 cores per biopsy. Fifty-seven pancreas samples collected using the 18-gauge needle were adequate for pathological evaluation for a 76% yield. With 15 biopsy attempts using the 20-gauge needle, 35 tissue cores were collected, for an average of 2.3 cores per biopsy. Twenty-nine pancreas specimens obtained from using the 20-gauge needle were adequate for analysis for an 83% yield. No major complications occurred. Only one incidence of minor complication was reported for a 2% complication rate. The only complication was local, mild bleeding at the biopsy site in one case. Air within the transplant pancreas as revealed by post-biopsy scans and streaky density appearing adjacent to the biopsy site occurred in a total of four cases and were not included. No complications were reported that required any invasive intervention. We conclude that percutaneous biopsy guided by ultrasound is a safe, simple, and effective method to detect pancreatic transplant rejection. Our results for biopsies compare favorably with other reported techniques in terms of effectiveness, complication rates, and ease of use. With its high success rate and low complications, ultrasound-guided percutaneous biopsy is an excellent method to sample pancreatic transplant.

Adult↗
PubMed2000

Monte Carlo assessment of computed tomography dose to tissue adjacent to the scanned volume.

The assessment of the radiation dose to internal organs or to an embryo or fetus is required on occasion for risk assessment or for comparing imaging studies. Limited resources hinder the ability to accurately assess the radiation dose received to locations outside the tissue volume actually scanned during computed tomography (CT). The purpose of this study was to assess peripheral doses and provide tabular data for dose evaluation. Validated Monte Carlo simulation techniques were used to compute the dose distribution along the length of water-equivalent cylindrical phantoms, 16 and 32 cm in diameter. For further validation, comparisons between physically measured and Monte Carlo-derived air kerma profiles were performed and showed excellent (1% to 2%) agreement. Polyenergetic x-ray spectra at 80, 100, 120, and 140 kVp with beam shaping filters were studied. Using 10(8) simulated photons input to the cylinders perpendicular to their long axis, line spread functions (LSF) of the dose distribution were determined at three depths in the cylinders (center, mid-depth, and surface). The LSF data were then used with appropriate mathematics to compute dose distributions along the long axis of the cylinder. The dose distributions resulting from helical (pitch = 1.0) scans and axial scans were approximately equivalent. Beyond about 3 cm from the edge of the CT scanned tissue volume, the fall-off of radiation dose was exponential. A series of tables normalized at 100 milliampere seconds (mAs) were produced which allow the straight-forward assessment of dose within and peripheral to the CT scanned volume. The tables should be useful for medical physicists and radiologists in the estimation of dose to sites beyond the edge of the CT scanned volume.

Computer Simulation↗
PubMed2000

Comparison of US utilization and technical costs before and after establishment of 24-hour in-house coverage for US examinations.

PURPOSE: To compare data regarding the cost and number of ultrasonographic (US) examinations performed for 6 months, before and after institution of 24-hour in-house sonographer coverage. MATERIALS AND METHODS: Data for a 6-month period during which US services were provided by a sonographer on call from 11 PM to 7 AM were compared with data for a 6-month period during which a sonographer was in house during this shift. RESULTS: With 11 PM to 7 AM on-call coverage, the sonographers performed 147 examinations in a 6-month period, an average of 0.81 examination per shift. After institution of in-house coverage for this shift, 792 US examinations were performed in 6 months, an average of 4.3 examinations per shift. The cost for 11 PM to 7 AM in-house sonographer coverage for 6 months was approximately $16,000 more than that for on-call coverage. This cost would be offset by revenues from one additional examination per night. The cost per examination for the 11 PM to 7 AM shift decreased from $124.70 to $43.33. CONCLUSION: At the authors' institution, 24-hour in-house sonographer coverage resulted in additional cost, which was offset by revenues from additional examinations. There was nearly a fivefold increase in the number of US examinations performed per shift. These examinations were performed more expediently, enabling more rapid patient triage.

California↗
PubMed2000

Radio-frequency electrocautery ablation of mammary tissue in swine.

PURPOSE: To establish the size, configuration, and histopathologic features of acute, subacute, and chronic radio-frequency (RF) electrocautery of mammary tissue in swine. MATERIALS AND METHODS: Eighteen RF treatments were performed in the mammary tissue of three domestic swine under ultrasonographic (US) guidance. Histopathologic examination was performed immediately after (acute animal); 2 weeks after (subacute animal); and 4 weeks after (chronic animal) treatment. RESULTS: In the acute animal, lesions were firm nodules on palpation and had a distinct line of demarcation between necrotic and viable mammary tissue (mean lesion volume, 14.24 cm(3); largest volume, 29.06 cm(3)). In the subacute animal, there was diffuse coagulation necrosis with neutrophilic infiltrates at the periphery (mean lesion volume, 6.46 cm(3); largest volume, 9.47 cm(3)), and two treatment areas had a secondary bacterial infection. In the chronic animal, lesions were still palpable and firm (mean lesion volume, 11.67 cm(3); largest volume, 25.5 cm(3)), and five of six treatment sites had an area of gray to white fibrotic tissue that blended with the surrounding tissue. However, one site had a pale yellow area of central necrosis surrounded by a fibrotic area. In both the subacute and chronic animals, two and one treatment site, respectively, had minimal areas of skin necrosis. CONCLUSION: RF ablation of breast tissue is feasible in this animal model. Problems included minimal skin erythema, residual firm treatment regions at 4 weeks, slightly variable margins of coagulation necrosis, and occasional bacterial infection.

Animals↗
PubMed1999

Sonographic detection of blunt hepatic trauma: hemoperitoneum and parenchymal patterns of injury.

OBJECTIVES: To determine the sensitivity and utility of emergency sonography for the detection of blunt hepatic injury (BHI) in patients with abdominal trauma and to describe parenchymal sonographic patterns of BHI. METHODS: This report was a prospective clinical study in which the findings of all patients who had emergency sonograms were recorded on a data sheet by the initial sonographer and interpreting physicians. All patients with hepatic injuries during this period were identified and physical examination, laboratory, computed tomographic and intraoperative findings were compared with the prospective data sheets. RESULTS: From January of 1995 to December of 1998, 2,622 emergency sonograms were performed, and in this group, a total of 146 patients had BHI. Emergency sonograms allowed detection of free fluid in 98 patients (67%), and parenchymal injury with no free fluid in seven patients (5%). There were 41 false negatives (28%). The most common pattern identified on a sonogram was a discrete area of increased echogenicity followed by a diffuse hyperechoic pattern. Seventy-six patients (52%) had concomitant intra-abdominal injuries, including spleen (n = 46), bowel (n = 30), and kidney (n = 19). There were 102 exploratory laparotomies performed. Abdominal tenderness or distention was present in 127 patients (87%), and 108 patients had right rib fractures (74%). Based on detection of free fluid, parenchymal injury, or both, the overall sensitivity of sonography for the detection of BHI was 72 % but was 98 % for grade III or higher injuries. CONCLUSION: Emergency sonography is sensitive for the detection of grade III or higher liver injuries resulting from blunt abdominal trauma. Sonography may also reveal BHI on the basis of parenchymal abnormality, with a discrete hyperechoic area the most commonly encountered pattern.

Adolescent↗
PubMed1999

Bowel and mesenteric injury: evaluation with emergency abdominal US.

PURPOSE: To assess emergency ultrasonography (US) for detection of bowel and mesenteric injury from blunt trauma. MATERIALS AND METHODS: For 3 years, prospective data on all patients undergoing emergency US were recorded. Patients with bowel and mesenteric injury were identified, and physical examination, laboratory, computed tomographic (CT), and intraoperative findings were compared with prospective data. RESULTS: From January 1995 to January 1998, emergency US was performed in 1,686 patients; 71 patients had bowel and mesenteric injury. Forty-one examinations were true-positive (i.e., with free fluid), and 30 were false-negative. Twenty-five of the 41 patients with true-positive US results had concomitant injuries that may have accounted for the free fluid, including liver, spleen, pancreas, gallbladder, kidney, and/or bladder injuries. The remaining 16 patients had isolated bowel and mesenteric injury. Bowel and mesenteric damage was identified intraoperatively in 70 patients. Twenty-nine of 30 patients with false-negative US examinations had abdominal tenderness. Sixteen patients with false-negative US results had bowel and mesenteric injury that was detected 12 or more hours after initial scanning. CONCLUSION: Free fluid in the abdomen is not detected in the majority of patients with isolated bowel and mesenteric injury. For clinical suspicion of bowel and mesenteric injury, observation, serial physical abdominal examination, and CT may be helpful in diagnosing this condition.

Adult↗
PubMed1999

Use of ultrasonography in the patient with acute renal trauma.

The purpose of this study was to assess the use of emergent ultrasonographic examination in acute traumatic renal injuries. Over a 3 year period, prospective data of all patients who had an emergency ultrasonogram were recorded. Thirty-two patients with 37 renal injuries were studied retrospectively to identify in how many patients the sonogram detected free fluid or a renal parenchymal abnormality. Free fluid in the abdomen was identified in 19 of 32 patients (59%). However, 12 of these 19 patients had concomitant injury, such as splenic rupture requiring splenectomy, severe liver lacerations, or bowel lacerations requiring repair, that were possible causes of the free fluid. Eliminating these patients, only seven of 20 patients with isolated renal injuries had free fluid in the abdomen (35%), whereas 13 of 20 patients (65%) had no evidence of free fluid. All seven patients with free fluid had moderate or severe renal injuries. Renal parenchymal abnormalities were identified on ultrasonograms in eight of 37 (22%) of injured kidneys. The abnormalities were detected more commonly in cases of severe injury (60%). In conclusion, acute injuries of the kidney from blunt abdominal trauma often are associated with significant splenic, hepatic, or bowel trauma. Isolated renal injuries frequently occur without the presence of free fluid in the abdomen. Furthermore, the ultrasonogram of the kidney often is normal with acute renal injuries, but it is more likely to be abnormal with severe (grade II or greater) renal injuries. Sonography may be used in the triage of patients with blunt abdominal trauma and possible renal injury. However, a negative ultrasonogram does not exclude renal injury, and, depending on clinical and laboratory findings, other imaging procedures such as computed tomography should be performed.

Abdominal Injuries↗
PubMed1998

The fetal head: borderlines.

After more than 20 years of using ultrasound to examine the fetal head, there are still areas of controversy. The size of the ventricular atrium or the anteroposterior measurement of the posterior fossa have been shown to be relatively stable throughout pregnancy. However, there are instances in which intracranial malformations occur with normal ventricular atrial measurements. Although there are more obvious posterior fossa defects such as Dandy-Walker malformation, there are other abnormalities such as Dandy-Walker variant that are difficult to detect. Another area of controversy surrounds dealing with the fetus with a choroid plexus cyst. Review and understanding of the current literature are needed to best manage these fetuses with choroid plexus cysts. Knowledge of central nervous system embryology and of technical pitfalls of sonography, and understanding the overlap between normal and abnormal anatomy are needed to obtain a more precise central nervous system diagnosis. This article will review some of the borderlines in examination of the fetal brain.

Brain↗
PubMed1998

Low-dose, fractionated radioimmunotherapy for B-cell malignancies using 131I-Lym-1 antibody.

PURPOSE: This trial was conducted to assess the toxicity and efficacy of 131I-Lym-1 in patients with either malignant B-cell non-Hodgkin's lymphoma (NHL) or chronic lymphocytic leukemia (CLL) using low-dose, fractionated radioimmunotherapy (RIT). MATERIALS AND METHODS: Thirty adult patients who had advanced B-cell malignancies (25 NHL and 5 CLL) had progressed despite standard therapy; 12 patients entered the trial with Karnofsky performance status (KPS) of equal to or greater than 60. Patients were treated with a series of intravenous doses of 131I-Lym-1 with a goal of reaching a cumulative dose in each patient of at least 300 mCi. All patients were Lym-1 reactive. Clinical responses and immediate toxicity were evaluable in all 30 patients and delayed toxicity in 26. RESULTS: Toxicity to Lym-1 antibody occurred with 28% of the 176 doses and was transient. Human antimouse antibodies (HAMA) were generated in 30% after a mean of 4 doses, but interrupted therapy in only 10% of the patients. Thrombocytopenia was dose-limiting; there were no deaths due to toxicity. Tumor regression occurred in 25 (83%) of the patients and was great enough, and durable enough, in 17 (57%) to qualify them as responders; 13 NHL patients and 4 CLL patients. Advanced disease often interrupted therapy prematurely. However, 18 patients received at least 180 mCi of 131I-Lym-1; 17 (94%) of these responded to the therapy. CONCLUSION: Although advanced disease often interrupted therapy prematurely, the results from 131I-Lym-1 therapy are clearly promising and warrant additional trials.

Adult↗