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Biomedical subjects

L A Mack

Publications and source records attributed to L A Mack.

At least 19 recordsLinked to original sources
PubMed2005

Education is the key to quality of surgery for rectal cancer.

Surgical quality assurance is a central issue in the treatment of rectal cancer and has led to substantial improvements in sphincter preservation, local control, and overall survival. Education or training as well as volume of practice are often cited as the major predictors of quality outcomes. While volume is a simple measure to analyze, it is likely a superficial or surrogate measure of quality surgery. It has been conclusively demonstrated that education, from total mesorectum excision workshops to nation-wide educational initiatives are effective methods of improving quality of care for the rectal cancer patient. New methods of quality assurance and improvement are being developed including prospective quality registers, the synoptic operative report, and pathology audits. It is imperative that improved measures of quality, other than volume, be implemented to audit our own practices, hospitals and regions with the goal of identifying issues that will improve outcomes for rectal cancer patients.

Canada↗
PubMed2004

Groin soft tissue tumors--a challenge for local control and reconstruction: a prospective cohort analysis.

BACKGROUND AND OBJECTIVES: Groin soft tissue tumors are associated with high local recurrence rates of 16-48% and postoperative complications in 40-68%. Neoadjuvant chemoradiation and aggressive reconstructive techniques were utilized to improve local control and complication rates in this challenging area. METHODS: Nine patients in this prospective series were treated with neoadjuvant chemoradiation (30 mg IV doxorubicin x 3d followed by 300 cGy/d x 10d) followed by surgery and two patients received radiation (5,000 cGy with tissue spacer) followed by surgery for tumors with a pelvic/retroperitoneal component. Surgery included resection plus reconstruction of the abdominal wall, myocutaneous flaps for large defects, and vascular reconstruction as necessary. RESULTS: The 11 consecutive patients presented with Stage I (30%), II (40%), or III (30%) disease. Four patients (36%) were operated on for possible incarcerated hernia prior to referral and two (18%) presented with recurrent tumors. Pathology included 10 sarcomas and 1 desmoid tumor; tumor grade was low (30%), moderate (40%), or high (30%). Local control (mean follow-up 55 months; minimum follow-up 36 months) and limb salvage rate was 100%. Minor wound complications not requiring re-operation occurred in three patients, lymphedema in two, and there were no postoperative hernias. CONCLUSIONS: Preoperative therapy provides excellent local control of groin soft tissue tumors. Current surgical techniques allow extensive resection with limb salvage, dependable primary wound healing and long-term integrity of the abdominal wall.

Abdominal Wall↗
PubMed1996

Three-dimensional ultrasonic angiography using power-mode Doppler.

To visualize the vascular anatomy of parenchymal organs, we have developed a system for producing three-dimensional ultrasonic angiograms (3D USA) from a series of two-dimensional power-mode Doppler ultrasound (PDU) scans. PDU scans were acquired using a commercial scanner and image-registration hardware. Two-dimensional images were digitized, and specially designed software reconstructed 3D volumes and displayed volume-rendered images. The geometric accuracy of our system was assessed by scanning a flow phantom constructed from tubing. The system was tested on patients by scanning native and transplanted kidneys, and placentas. Three-dimensional images of the phantoms depicted the spatial relationships between flow within the tubing segments and contained less than 1 mm of geometric distortion. Three-dimensional images of the kidney and placenta demonstrated that spatial relationships between vasculature structures could be visualized with 3D USA. Applications of this new technique include analysis of vascular anatomy and the potential assessment of organ perfusion.

Angiography↗
PubMed1996

Isolated fetal choroid plexus cysts and karyotype analysis: is it necessary?

The purpose of this study was to evaluate the risk of fetal aneuploidy in the presence of isolated choroid plexus cysts and to evaluate the results obtained from our institution and those reported previously in the English literature. All patients with fetal choroid plexus cysts on prenatal ultrasonography were offered genetic counseling and amniocentesis for fetal karyotyping. Seven of 274 fetuses, 2.6% (95% confidence interval = 1.0 to 5.2%), with isolated choroid plexus cysts were aneuploid. Literature analysis located 23 other reports of 1537 fetuses with isolated choroid plexus cysts; 26 were karyotypically abnormal, 1.7% (95% confidence interval = 1.0 to 2.4%). When evaluating only those patients whose indication for amniocentesis was choroid plexus cysts (i.e., eliminating those patients with advanced maternal age or abnormal serum screening) the risk of having a fetus with trisomy 18 changed little, 1.9% (95% confidence interval = 0.4 to 5.5%). Our data, combined with those of the literature, suggest that the risk of finding an abnormal fetal karyotype in the presence of isolated choroid plexus cysts is at least 1% and may be as high as 2.4%. On the basis of these results, genetic counseling and prenatal diagnosis should be offered to these patients.

Aneuploidy↗
PubMed1995

Hepatic arterial anatomy: demonstration of normal supply and vascular variants with three-dimensional CT angiography.

Three-dimensional (3D) helical computed tomographic (CT) angiography is a promising method of determining vascular anatomy. This technique is useful in delineating the arterial anatomy of the liver, demonstrating the normal anatomy and vascular variants in a highly visual fashion. The "typical" hepatic arterial anatomy occurs in only 55% of the population, and numerous variants exist; the standard classification system for hepatic arterial anatomy includes 10 variations. After helical scanning, postprocessing with reconstruction algorithms such as shaded surface display and maximum-intensity projection provides highly graphic, easily understandable views of vascular anatomy. The 3D CT angiograms, with their global view of the anatomy and inherent advantage of volumetric rotation of the vascular system, are useful to surgeons and others with limited experience in interpreting axial anatomy. Determination of hepatic arterial anatomy with 3D CT angiography has already been shown to be clinically useful in patients being evaluated for liver transplantation.

Adult↗
PubMed1995

Ultrasonography.

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Humans↗
PubMed1995

Hepatic arterial anatomy in transplantation candidates: evaluation with three-dimensional CT arteriography.

PURPOSE: To assess the utility of three-dimensional (3D) hepatic helical computed tomographic (CT) arteriography as a replacement for conventional angiography in the evaluation of the arterial anatomy of patients being considered for liver transplantation. MATERIALS AND METHODS: Three-dimensional CT arteriograms were obtained in 115 patients. Seventeen patients also underwent conventional angiography, and 16 patients who did not undergo angiography underwent hepatic transplantation. RESULTS: Among the 3D CT arteriograms, 106 delineated the major arteries that supplied the liver. Nine were considered technical failures. In the 17 patients with angiographic correlation, there was only one marked disagreement with 3D CT arteriography. In the 16 patients with surgical correlation, no marked discrepancies were found. CONCLUSION: In transplantation candidates, successful 3D CT arteriography was as accurate as angiography in the assessment of hepatic arterial anatomy. It was also safer, more convenient, and more easily tolerated. Conventional CT plus 3D CT arteriography was only 25% as expensive as the cost of conventional CT and conventional angiography.

Adult↗
PubMed1995

Renal perfusion: pharmacologic changes depicted with power Doppler US in an animal model.

PURPOSE: To evaluate the ability of power Doppler ultrasonography to depict changes in renal perfusion after pharmacologic manipulations. MATERIALS AND METHODS: Six domestic swine were intubated and anesthetized. The right renal artery was catheterized for injection of epinephrine (100 micrograms) and papaverine (2 mg/kg). Intraarterial blood pressure, heart rate, and oxygen saturation were measured continuously. Longitudinal images of the kidney were obtained, and the power Doppler color map was analyzed subjectively and by computer at baseline and at the time of maximum drug effect. RESULTS: Epinephrine produced vasoconstriction with a diminished power Doppler color map and a decrease in both subjective and computer scores. After papaverine-induced vasodilatation, the power Doppler map was enhanced, as reflected by increased subjective and computer scores. CONCLUSION: The power Doppler color map reflects anticipated changes in renal perfusion after alterations in blood flow by vasoactive drugs.

Animals↗
PubMed1995

Fetal aqueductal stenosis diagnosed sonographically: how grave is the prognosis?

OBJECTIVE: Aqueductal stenosis is a common cause of fetal hydrocephalus. Published studies of neonates with aqueductal stenosis have noted variable outcomes, with normal development seen in 24-86% of cases. In an attempt to better assess long-term outcomes in cases diagnosed in utero and to determine what prenatal sonographic findings might be used to predict prognosis, a retrospective analysis of patients with aqueductal stenosis was done. MATERIALS AND METHODS: Fifty-three consecutive cases of aqueductal stenosis discovered in utero at two high-risk obstetrical centers in Seattle between 1980 and 1993 were studied. Parents elected to continue pregnancy in 39 of these cases. Two months to 10 years of long-term follow-up was available in 30 patients, who form our study group. Prenatal sonograms, postnatal cranial ultrasound, and head CT and MR were evaluated. Prenatal sonographic data collected included the biparietal diameter, size of the lateral and third ventricles, the ratio of the two, and thickness of the frontoparietal cortical mantle. Medical records provided an assessment of development based on physical examination, meeting of major milestones, and neuropsychological testing. The in utero diagnosis of aqueductal stenosis was confirmed by postnatal CT, MR imaging, sonography, or autopsy. RESULTS: Within the study group of 30 patients, eight died in the postnatal period and four died subsequently. Of the 22 patients with adequate postnatal follow-up, moderate or severe developmental delay was present in 16 (73%). Normal developmental milestones were met in only three (10%) of all 30 patients and in 14% of those surviving the neonatal period. Although size of the lateral and third ventricles was not a useful predictor of long-term prognosis, the ratio of the two, as well as thickness of the frontoparietal cortical mantle, was weakly associated with long-term prognosis. No correlation was found between biparietal diameter and outcome. CONCLUSION: As compared with previous reports, prenatal diagnosis of aqueductal stenosis carries a grave prognosis. Twelve of the 30 patients died, for an overall mortality of 40%. Normal development was seen in only 10%, significantly less than in prior studies.

Cerebral Aqueduct↗
PubMed1995

Evaluation of the portal venous system before liver transplantation: value of phase-contrast MR angiography.

OBJECTIVE: The purpose of this study was to assess the accuracy of phase-contrast MR angiography with gadolinium in evaluating the patency and blood flow direction of the portal venous system; the presence, extent, and type of varices; and the patency of surgical decompressive shunts in patients before liver transplantation. This information is essential in management and care of patients with chronic liver disease and portal hypertension and those who are candidates for liver transplantation. SUBJECTS AND METHODS: Twenty-four patients with portal venous hypertension were evaluated with phase-contrast MR angiography. Two patients had surgical splenorenal shunts and one had a mesocaval shunt. Phase-contrast angiograms were acquired as a series of two-dimensional sequential coronal sections during breath-holding and after IV administration of gadopentetate dimeglumine. Correlative findings from color flow Doppler sonography, contrast-enhanced CT scanning, and conventional angiography were available in 23, 20, and 10 patients, respectively, and were used as standards. The images from each technique were analyzed independently for patency of and flow direction in the portal vein, splenic vein, superior mesenteric vein, and surgically created shunts, and for detection, distribution, and extent of five variceal groups. RESULTS: Findings from phase-contrast MR angiography completely agreed with those of sonography, CT scanning, and conventional angiography. The main portal vein was patent in 18 patients, stenosed in one, partially thrombosed in one, and occluded in four. Phase-contrast MR angiography correctly showed hepatofugal flow in three patients and hepatopetal flow in 17 patients. Both the splenic and superior mesenteric veins were patent in 20, partially thrombosed in one, and occluded in three cases. Phase-contrast MR angiograms showed 85% of the variceal groups, and MR rating of variceal size was not significantly different from that of CT rating. Phase-contrast MR angiography correctly showed the patency of all three surgical decompressive shunts. CONCLUSION: Phase-contrast MR angiography is accurate for evaluating the patency and flow direction of the portal venous system, detecting and determining the distribution and extent of varices, and assessing the patency of surgically created shunts. Therefore, it is a reliable and noninvasive technique that can provide crucial information in the preoperative workup of liver transplant recipients.

Adult↗
PubMed1995

Association of sonographically detected subacromial/subdeltoid bursal effusion and intraarticular fluid with rotator cuff tear.

OBJECTIVE: Although an association between sonographically detected joint fluid and rotator cuff disease has been reported, the significance of sonographically detected subacromial/subdeltoid bursal effusion has not been studied. We examined a group of patients who had shoulder sonography and surgery to determine the association between bursal and joint effusion and surgically proved tears of the rotator cuff. MATERIALS AND METHODS: We retrospectively reviewed the preoperative shoulder sonography reports of 163 patients for the presence of fluid within the subacromial/subdeltoid bursa or glenohumeral joint. Surgical reports were obtained to determine the status of the rotator cuff. The sonographic reports of 232 asymptomatic shoulders were also reviewed to determine the prevalence of fluid within the subacromial/subdeltoid bursa or the glenohumeral joint. RESULTS: Sixty-seven (41%) of the 163 patients had a joint effusion, bursal fluid, or both. Joint effusion alone was seen in 35 patients. Fourteen of these had a normal rotator cuff at surgery, and 21 had a rotator cuff tear (sensitivity, 22%; specificity, 79%; positive predictive value, 60%). Bursal fluid alone was seen in 10 patients, seven of whom had a rotator cuff tear (sensitivity, 7%; specificity, 96%; positive predictive value, 70%). In 22 patients, fluid was seen in both the bursa and the joint; 21 had surgically proved rotator cuff tears (sensitivity, 22%; specificity, 99%; positive predictive value, 95%). Of the 232 asymptomatic shoulders, 16 (6.9%) had isolated joint effusions, eight (3.4%) had isolated bursal effusions, and four (1.7%) had both joint and bursal effusions. CONCLUSION: The sonographic finding of intraarticular fluid alone (without bursal fluid) has both a low sensitivity and a low specificity for the diagnosis of rotator cuff tears. However, the finding of fluid in the subacromial/subdeltoid bursa, especially when combined with a joint effusion, is highly specific and has a high positive predictive value for associated rotator cuff tears. Sonographically detected fluid in both the joint and the bursa is an uncommon finding in asymptomatic shoulders. The sonographic observation of fluid in the subacromial bursa, either isolated or combined with a joint effusion, should prompt a careful evaluation of the supraspinatus tendon for tear.

Acromion↗
PubMed1995

Rotator cuff.

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Adult↗
PubMed1994

Meningomyelocele: management in utero and post natum.

We report a four year follow-up of 39 of 47 infants born after pre-labour Caesarean section and 68 of 79 born vaginally. Loss of motor function due to late complications was more frequent in the Caesarean section group (Fisher's Exact; P = 0.004). However, the means of the differences between the X-ray levels (measured as the last intact vertebral arch seen on standard anteroposterior roentgenograms of the spinal column) subtracted from the motor levels still favour Caesarean section (mean = 3.24; SD = 2.7) over vaginal delivery (mean = 1.2; SD = 2.7) (Student's t-test; P = 0.0003). The frequencies of other complications, death and neonatal meningitis, were not significantly different. Another 38 infants born by Caesarean section after labour were more paralysed (mean of X-ray and motor difference = 1.8, SD = 2.2) following rupture of amniotic membranes than those with intact amniotic membranes with or without labour (mean = 3.4; SD = 2.2) (Student's t-test; P = 0.0067). The differences between X-ray and motor levels for patients born by Caesarean section with intact amniotic membranes and without labour (mean = 3.6; SD = 2.4) were not significantly different from those with labour and intact amniotic membranes (mean = 2.89; SD = 1.5). The number of new cases of meningomyelocele presenting to our clinic has decreased from an average of 30 per year between 1970 and 1987 to 14 between 1988 and 1992.

Cesarean Section↗
PubMed1994

A comparison between preoperative magnetic resonance and intraoperative ultrasound tumor volumes and margins.

A major obstacle in surgical neuro-oncology is differentiating the interface between tumor and normal brain. Twenty-two brain tumors were evaluated preoperatively with magnetic resonance imaging. Intraoperative ultrasonography was used to guide surgical resection of these tumors, and results were compared with surgical and pathologic findings. Ultrasound tumor volume estimates were larger than T1 gadolinium-enhanced and T1 non-gadolinium-enhanced volumes, but these differences did not reach statistical significance. Similarly T2 volumes were larger than the corresponding sonographic volumes, except for the subset of low-grade gliomas, and in that instance the difference was small, but again the differences were not statistically significant. Ultrasonography enhanced identification of infiltrating tumor cells beyond falsely underestimated tumor margins as defined by T1 images. Ultrasound images helped differentiate edema as seen on T2 images from solid tumor and normal brain. The information gained from ultrasound images can be used to enhance tumor resection and improve patient survival and quality of life.

Adolescent↗
PubMed1994

The outcome of fetal myelomeningocele brought to term.

14 years experience with 354 infants born with myelomeningocele are reviewed in view of prelabor and pre-rupture of amniotic membranes vs vaginal delivery or delivery by cesarian section after labor and rupture of amniotic membrane. The apparent lack of effect of severity of impairment determined by prenatal diagnosis on parental decision to carry their baby to term, the negative effect on motor function of kyphos or congenital kyphoscoliosis, the equivocal effect of breech presentation with or without rupture of amniotic membranes and the beneficial effect of prelabor and prerupture of membranes delivery of selected infants is discussed. The need for further multiple center, collaborative study to identify the contribution of a number of factors influencing the outcome of fetuses diagnosed as having myelomeningocele is emphasized.

Breech Presentation↗