Extending the role of liposuction in body contouring with ultrasound-assisted liposuction

The initial experience with ultrasound-assisted liposuction in treating difficult fibrous areas, such as gynecomastia, hitherto not uniformly responsive to traditional suction-assisted lipoplasty, has led to the evolution and improvement of ultrasound-assisted liposuction techniques. This prospective study examined 114 consecutive patients treated with ultrasound-assisted liposuction over a 13-month period, from September of 1996 to September of 1997. The means by which this procedure helps achieve fat contouring differs from that of suction-assisted lipoplasty. Ultrasound-assisted liposuction removes fat through a fat emulsification process termed "cavitation," whereas suction-assisted lipoplasty achieves contouring through the mechanical avulsion of fat. The technique for the use of ultrasound-assisted liposuction has changed significantly from our initial series of patients to our current technique. To optimize the benefits of both ultrasound-assisted and traditional suction-assisted lipoplasty, we use a three-stage technique consisting of infiltration, ultrasound-assisted sculpturing, and suction-assisted lipoplasty for evacuation and final contouring. This has decreased our operative time, minimized complications, and optimized our body contouring results. Data were collected intraoperatively, including treatment times, treatment volumes, and treatment areas for both suction-assisted and ultrasound-assisted lipoplasty. A total of 114 patients were treated with ultrasound-assisted liposuction between September of 1996 and September of 1997. There were 23 male patients and 91 female patients. In general, the average total volume removed with this procedure decreased by about 50 percent throughout the series, whereas the suction-assisted lipoplasty volume increased correspondingly by 50 percent. Overall, suction-assisted lipoplasty volume was approximately two times ultrasound-assisted liposuction volume in the same area. Exceptions to this include the dense fibrous areas such as the back and male breast, where aspiration volumes were approximately equal. The total ultrasound-assisted liposuction treatment times were reduced after our initial 30 patients, and suction-assisted lipoplasty times increased. Total aspiration rates in our later patients averaged 36.2 cc/per minute for ultrasound-assisted and 58.4 cc/per minute for suction-assisted lipoplasty, whose rates were approximately 1.5 to 2 times faster than for ultrasound-assisted liposuction in most areas. After using this technology in our initial series of 30 patients, it became apparent that ultrasound was not a substitute for suction-assisted lipoplasty but rather a natural complement. We have found that the marriage of the techniques enhances results and minimizes complications, such as seromas, which have been reported to be 11.4 percent with ultrasound-assisted liposuction alone and are 2.6 percent in our series.     

Suppression of kindling epileptogenesis in rats by intrahippocampal cholinergic grafts

The objective of our study was to investigate the effects of ultrasonic energy on tissues, using a porcine model, performed under various instrumental and procedural parameters. Domestic pigs were anesthetized and prepared for surgery. An incision was made on the side of the hip randomly assigned to the right or left side. Tumescence solution was infiltrated via a blunt tip, small diameter cannula, followed by performance of standard liposuction. On the contralateral side, a similar incision was made. For ultrasonic liposuction experiments without the sheath, a percutaneous introducer was inserted into the incision, which was protected at the entry site from contact with the cannula. Tumescence solution was infiltrated via a blunt tip, small diameter cannula, and then the site was treated with ultrasonic energy at maximum output from the machine with liposuction concurrent through the hollow cannula. The experiments with the sheath did not require a pretreatment with tumescence solution but consisted of tumescence solution pumped through the sheath at a low infusion rate, with concurrent treatment utilizing ultrasonically assisted liposuction through the central lumen of the cannula. In all cases, the lipoaspirate was preserved for biochemical analysis. After treatment, the pigs were euthanized, and samples for histopathology were taken. The pigs were then perfused with a radio-opaque solution through the left ventricle following preperfusion with saline. The groups were ultrasound-assisted liposuction with sheath (n = 3), ultrasound-assisted without sheath (n = 4), and tumescence alone (n = 1), with standard liposuction performed on the contralateral side for all ultrasound-assisted liposuction animals. The lipoaspirates from the ultrasonically assisted liposuction with the sheath showed significantly less blood loss (measured as hemoglobin in the aspirate) than standard liposuction (p = 0.012) at comparable levels of fat (measured as triglycerides in the aspirate). The lipoaspirates from ultrasound-assisted liposuction without the sheath showed blood loss comparable to that experienced with standard liposuction. The ratio of hemoglobin to triglyceride was lowest in the ultrasound-assisted group with (p = 0.01) and without (p = 0.06) the sheath when compared to traditional liposuction. In both of these treated groups, the radiograms of the perfused areas showed significantly less vascular disruption when compared with suction-assisted liposuction. Histopathologic examination of specimens taken from various treated areas showed substantial tissue damage comparable in ultrasound- and suction-assisted liposuction treated groups. This preliminary experimental study showed that ultrasound-assisted lipoplasty is comparable to traditional suction-assisted lipoplasty. Treatment with ultrasound provided more significant hemoglobin/triglyceride ratios, indicative of more lipid aspirated per hemoglobin lost, and better preservation of vascular tissues as demonstrated by our perfusion studies. Treatment with the sheath showed a significantly lower hemoglobin release with a diminished volume infused into the subcutaneous space during the procedure.     

Liposuction: procedure for focal volume reduction and body contour remodeling

Liposuction is the most commonly used procedure for focal reduction of body fat deposits and remodeling the body contour. The procedure consists in aspirating fat from lamellar deposits using a vacuum source connected to a cannula that is passed bluntly through fatty tissue. Adjuncts to the procedure include infiltration of solutions to aid in fat removal or to limit blood loss and the application of ultrasonic energy to lyse fat cells before suction aspiration. Surgical history, theory, procedures, indications, potential complications, and guidelines are discussed herein.     

The impact of liposuction on body fat

Routine liposuction has very low perioperative complication rates and is thus considered to be innocuous. Some authors have even proposed that large-volume liposuction could be therapeutic. However, because subcutaneous adipose tissue has nutritional and thermodynamic metabolic functions proportional to the absolute amount and the distribution of fat, it is possible that removal of subcutaneous adipose tissue might be detrimental. We measured the amount of fat removed by large-volume (>1000 cc) liposuction and expressed the results in terms of absolute and relative changes in total body fat and in visceral adipose tissue (nonsubcutaneous adipose tissue) in 63 normal weight to mildly obese women (n = 51) and men (n = 12). Aspiration of 1.5 +/- 0.7 kg (mean +/- SD) of lipid in women removed 9.2 +/- 3.2 percent of body fat or 10.5 percent of subcutaneous adipose tissue corresponding to a 12-percent increase in the ratio of visceral to subcutaneous adipose tissue. One third of the women (n = 17) had a mean increase of 16 percent (range 13 to 21 percent) in the proportion of visceral fat. In the 12 men, aspiration of 1.7 +/- 0.6 kg of lipid removed 9.8 +/- 2.9 percent of body fat or 12.7 +/- 3.6 percent of subcutaneous adipose tissue, resulting in a 14-percent increase in the ratio of visceral to subcutaneous fat. The correlation between aspirate and body mass index was 0.57 (p < 0.001). Although large-volume subcutaneous liposuction removed relatively little body fat, it led to significant increases in the proportion of visceral adipose tissue. Because the proportion of visceral adipose tissue is a risk factor for metabolic complications of obesity, the metabolic effects of large-volume liposuction need to be evaluated.     

Liver transplantation: review of the literature. Part 3: Medical complications

The first attempted human orthotopic liver transplantation, in 1963, involved a child with biliary atresia, who died on the operating table as a result of uncontrollable coagulopathy. Improvements in immunosuppression, surgical technique, medical imaging and postoperative care, as well as more stringent patient selection, have allowed the development of liver transplantation and its universal acceptance as the treatment for a variety of liver diseases. The radiologist plays a major role in the multidisciplinary transplantation team and must be familiar with each stage of orthotopic liver transplantation and its associated complications. In the first article of this series (Can Assoc Radiol J 1997;48[3]: 171-178), the authors reviewed the anatomic features and current concepts relevant to orthotopic liver transplantation. In the second article (Can Assoc Radiol J 1997;48[4]: 231-242), they discussed the vascular and biliary complications of the operation. This, the third and final article in the series, covers the medical complications.     

Measurement of the ultrasonic attenuation of fat at high frequency

RATIONALE AND OBJECTIVES: High-frequency ultrasound devices are often limited by a decreased depth of acoustic imaging caused by the increased attenuation of tissue at high frequencies. We investigated the role of adipose tissue in this phenomenon. METHODS: A substitution technique was used to calculate the ultrasonic attenuation (decibels per centimeter) of fresh samples of sheep rumen, omental fat, and back fat and swine back fat and various concentrations of bovine milk fat at 22 degrees C and 37 degrees C for frequencies of 15 and 20 MHz. RESULTS: The attenuation was significantly higher for sheep adipose tissue than for the intestinal wall, in descending order, omental fat, back fat, and rumen wall (P < 0.01). A correlation was found between bovine milk fat concentrations and attenuation at both frequencies (R2 > 0.9). The attenuation of adipose tissues decreased significantly with an increase in temperature (P < 0.01), whereas the attenuation of sheep rumen showed no significant change (P > 0.1). CONCLUSIONS: The ultrasonic attenuation of fat may contribute to limitations on the use of high-frequency ultrasound in clinical situations in which adipose tissue is present.     

Extracranial neuroblastomas and neurological complications

Between October 1989 and March 1997, 25 pediatric inpatients were treated for primary extracranial neuroblastoma (NB; n=20) or ganglioneuroblastoma (GNB; n=5) at the University of Istanbul, Institute of Pediatric Oncology, and these children were the subjects of this retrospective study. Seventeen (68%) of these patients experienced 19 neurological complications during the course of their disease. Fourteen had nervous system metastases or invasion. Nonmetastatic complications, including CNS infections (n=3) and new onset of seizures (n=2) secondary to metabolic encephalopathy were seen in 5 cases. By the time of the final analysis of the results, 8 of the 17 patients with neurological complications had died, 7 had either been lost to follow-up (n=4) or were in the terminal stage of their disease (n=3), and 2 were in remission. Both of the patients who were in remission had dumbbell neuroblastoma (DNB), and 1 of them, with congenital DNB, also had neurological sequelae, characterized by paraplegia and neurogenic bladder. Neurological complications occurred in 68% of NB and GNB cases. Metastatic complications were more common than nonmetastatic complications and had a poor prognosis. Neurological complications were the primary cause of mortality in this study, mortality being related to neurological complications in 63% of cases, and the final outcome was worse than expected. However, regardless of any differences in social, economic and geographic factors and different treatment protocols for NB in different pediatric oncology institutions, neurological complication rates in pediatric NB are similar in all.     

Acute, life-threatening complications of lung transplantation

Acute, life-threatening complications of lung transplantation are common in all reported series. The clinical courses and images of 70 patients who underwent heart-lung (n = 5), bilateral sequential lung (n = 31), or single-lung (n = 38) transplantation were retrospectively reviewed. Sixty-five acute, life-threatening complications occurred in 26 patients (37%) within 3 months after transplantation. Nine deaths occurred as a result of these complications for a mortality rate due to acute complications of 13%. The deaths were a result of bleeding (n = 4), sepsis (n = 2), severe acute rejection and adult respiratory distress syndrome (n = 1), multiorgan failure (n = 1), and diffuse alveolar damage and respiratory failure (n = 1), a distribution of causes similar to those in other reported series. Specific diagnoses that can be made with imaging include hemothorax, lung torsion, pneumomediastinum, pulmonary embolism, pneumothorax, bronchial anastomotic dehiscence, lung collapse, paralysis of the diaphragm, and sternal dehiscence.     

Fetal complications of amniography

In a series of 241 amniograms, there were two cases of fetal tissue damage resulting from the subcutaneous injection of contrast material. Details of these two cases are given and the damage sustained illustrated. Measures designed to prevent such complications are outlined, together with recommendations for its management, should such a complication occur.     

Safety considerations and fluid resuscitation in liposuction: an analysis of 53 consecutive patients

There is no agreement as to appropriate fluid resuscitation in patients undergoing liposuction. This has assumed greater significance, as surgeons have undertaken larger volume aspirations (> or = 4 liters) and the potential complications of hypovolemia and fluid overload have materialized. This prospective study of 53 consecutive healthy patients undergoing liposuction using a superwet technique served to develop general guidelines for safe perioperative fluid management, especially in regard to large-volume aspirations. In this context, "aspirate" is defined as the total fat and fluid that is removed during liposuction. All patients were monitored using standard noninvasive hemodynamic monitoring. Thirty-six patients were monitored perioperatively with Foley catheters. The 53 patients underwent liposuction alone. We did not include patients who underwent concurrent aesthetic surgical procedures because our intention was to establish fluid administration guidelines for the liposuction patient. There were no significant complications in our series. The intraoperative fluid ratio, defined as (intravenous fluid + infiltrate)/aspirate, was 2.1 for the small-volume group and 1.4 for the large-volume group. These values were significantly different (p < .001, t test). Average urine output in the operating room and recovery room and on the floor was satisfactory (> 0.5 to 1 cc/kg/hr) and did not relate to volume aspirated (p = 0.21, 0.91, and 0.6, respectively, t test). Four patients who underwent "large-volume" aspirations (> or = 4 liters) had transient hypotension, which was immediately responsive to crystalloid fluid boluses in the first postoperative hours. All other patients required only maintenance intravenous crystalloid postoperatively until oral intake had been resumed. There were no statistically significant differences in postoperative fluid administration between the small- and large-volume groups. Ninety-three percent of patients were discharged within 24 hours of surgery. Our suggested guidelines for fluid resuscitation based on this retrospective study are as follows: (1) small volume (< 4 liters aspirated): maintenance fluid + subcutaneous wetting solution; (2) large volume (> or = 4 liters aspirated): maintenance fluid + subcutaneous wetting solution + 0.25 cc of intravenous crystalloid per cc of aspirate removed after 4 liters. This formula has since been used in the care of 94 patients who have undergone liposuction exclusively. All patients have had unremarkable hospital courses. These guidelines do not replace sound clinical judgment. Good communication between the surgeon and anesthesiologist is critical to optimal patient care and safety.     

Abdominal obesity and its metabolic complications: implications for the risk of ischaemic heart disease

Although the health hazards of obesity are well established, obese individuals are not all at equal risk of developing a disease, which reflects the heterogeneity of this condition. The regional distribution of body fat is now recognized as a very important component of the obesity-related health hazards. Epidemiological studies have shown that abdominal obesity, that is, a preponderance of fat in the abdominal area, is a better predictor of both cardiovascular disease and type 2 diabetes than obesity per se. It is now generally accepted that the fat located within the abdominal cavity, the visceral fat, is the best correlate of most of the highly atherogenic metabolic complications seen in individuals with abdominal obesity. These include, among others, insulin resistance and hyperinsulinaemia, hypertriglyceridaemia, reduced plasma high-density lipoprotein (HDL) cholesterol concentrations and an increased number of small, dense low-density lipoprotein (LDL) particles. This review summarizes the evidence that these metabolic complications may account to a large extent for the increased risk of cardiovascular disease associated with abdominal/visceral obesity. Abdominal obesity may be the most prevalent denominator of highly atherogenic dyslipidaemic and hyperinsulinaemic/insulin-resistant states in affluent, sedentary societies. Targeting individuals with this high-risk trait in primary prevention is therefore crucial if we are truly to have an impact on the incidence of cardiovascular disease.     

Reducing early technical complications in gastric bypass surgery

BACKGROUND: The incidence of complications following gastric bypass surgery has decreased markedly over the last 30 years; nevertheless, significant morbidity and mortality is still associated with this procedure. Much of the improved risk of this technique can be attributed to the numerous modifications that have taken place in its evolution. METHODS: We compared our series of 640 primary cases of vertical banded gastroplasty-Roux-en-Y gastric bypass (VBG-RGB), a form of gastric bypass, with gastric bypass series reported in the literature from 1966 to 1996. Incidences considered were those of subphrenic abscess, gastrointestinal leaks, obstruction of the excluded segment of gastrointestinal tract, splenectomy and death. RESULTS: The overall trend during the last 30 years has been a reduction in the rate of major complications. In our series, we had one major complication, a subphrenic abscess. This compares favorably with the incidence of major complications reported in the literature. CONCLUSIONS: The gastric bypass is a significantly safer operation today than three decades ago. We believe that the relatively low complication rate of VBG-RGB results from: (1) the anatomic location of the gastric pouch; (2) the type of stapling device used in its construction; (3) a pouch outlet restricted by a prosthetic band rather than a narrow anastomosis; and (4) the construction of a retrocolic, retrogastric Roux-en-Y gastrojejunal anastomosis.     

Use of preoperative subcutaneous "wetting solution" and epidural block anesthesia for liposuction in the office-based surgical suite

Uniform saturation of subcutaneous fat using the "wetting solution" formula described by Klein for his "tumescent technique" has been shown to decrease operative blood loss associated with liposuction procedures and to eliminate the requirement for general anesthesia for selected patients. However, we found this infusate provided an inadequate level of anesthesia for many of our patients. We use preoperative infusion of Klein's epinephrine and lidocaine containing wetting solution in our lipoplasty practice only for control of blood loss and postoperative pain. Our anesthetic of choice for liposuction is the epidural block technique, which provides consistent intraoperative comfort for the patient. We report our experience with 85 consecutive lipoplasty patients who underwent liposuction under epidural anesthesia after subcutaneous fat perfusion with Klein's wetting solution. Our epidural block technique uses the rapidly metabolized local anesthetic agent, chloroprocaine, which has the lowest systemic toxicity risk of any local anesthetic agent. Chloroprocaine's anesthetic characteristics are particularly well suited for the outpatient surgery patient with few undesirable side effects.     

Liver transplantation: review of the literature. Part 2: Vascular and biliary complications

The first attempted human orthotopic liver transplantation, in 1963, involved a child with biliary atresia, who died on the operating table as a result of uncontrollable coagulopathy. Improvements in immunosuppression, surgical technique, medical imaging and postoperative care, as well as more stringent patient selection, have allowed the development of liver transplantation and its universal acceptance as the treatment for a variety of liver diseases. The radiologist plays a major role in the multidisciplinary transplantation team and must be familiar with each stage of orthotopic liver transplantation and its associated complications. In the first article of this series (Can Assoc Radiol J 1997;48[3]:171-178), the authors reviewed the anatomic features and current concepts relevant to orthotopic topic liver transplantation. In this, the second article, they discuss the vascular and biliary complications of the operation, and the third article will cover the medical complications.     

Late complications in patients with pectoral defibrillator implants with transvenous defibrillator lead systems: high incidence of insulation breakdown

As the majority of ICDs with transvenous leads are now implanted in the pectoral region, complications associated with the technique are being identified. To determine the incidence of lead complications in patients with transvenous defibrillator leads and ICDs implanted in the pectoral region, 132 unselected consecutive patients with transvenous defibrillator leads had ICDs implanted in the pectoral region. Three lead systems were used: (1) lead system 1 (45 patients) consisted of a transvenous pacing sensing lead and a superior vena cava coil with a submuscular patch used for defibrillation; (2) lead system 2 (36 patients) utilized a CPI Endotak lead system; and (3) lead system 3 (51 patients) utilized a Medtronic Transvene lead system. Patients were followed for 3-54 months (cumulative 2,269, mean 18 months). The average duration of follow-up with the three systems was 32, 12 and 11 months, respectively. At 30 months follow-up, all three lead systems had a low incidence of complications. However, there was a 13% overall incidence (45% actuarial incidence) of erosion of the insulation of the pacing sensing lead of system 1 at 50 months of follow-up. All lead complications were seen in patients with ICDs whose weights were > 195 g and volumes > 115 cc. The erosion was probably a consequence of the pressure by the large ICD against the lead in the pectoral pocket. Follow-up with lead systems 2 and 3 is relatively short (average 12 months) but no lead erosions were seen. Pectoral implantation of ICDs with long transvenous leads and large generators is associated with a moderate risk of late complications in the form of insulation breaks caused by pressure of the generator against the leads. The use of less redundant leads coupled with smaller ICDs will probably eliminate this complication.     

Relationships between dietary fat, body fat, and serum lipid profile in prepubertal children

OBJECTIVE: The purpose of the study was to test the hypothesis that dietary fat components were associated with the serum lipid profile independent of ethnicity, body fat, and fat distribution in prepubertal children. RESEARCH METHODS AND PROCEDURES: Sixty-six children (45 African American and 21 Caucasian), aged from 4 to 10 years, were recruited into the study. Dietary total fat, saturated fat, monounsaturated fat, and polyunsaturated fat were estimated by averaging two 24-hour diet recalls. Fasting serum triacylglycerol, total cholesterol, and high-density lipoprotein cholesterol were analyzed, and low-density lipoprotein cholesterol (LDL-C) was calculated by the method of Friedewald. Body composition and fat distribution were measured by dual energy X-ray absorptiometry and computed tomography. RESULTS: Children in both ethnic groups tended to overreport their dietary intake relative to total energy expenditure by 18%. African American children consumed more energy from total fat (35.3% vs. 31.5%, p<0.05), saturated fat (13.7% vs 12.2%, p<0.05), protein (16.4% vs. 13.2%, p=0.02), and less from carbohydrate (48% vs. 57.1%, p<0.01) than Caucasian children. There was no significant correlation between dietary fat and either serum lipids or body fat indices after adjusting for nonfat energy intake and total lean tissue mass. Total body fat (r=0.32), subcutaneous abdominal adipose tissue (r=0.39), and intra-abdominal adipose tissue (r=0.42) were positively related to serum triacylglycerol; these associations remained significant in a multiple linear regression model in which body fat indices were adjusted for ethnicity, total lean tissue, dietary total fat, and nonfat intake. DISCUSSION: Our results do not support a link between dietary fat and serum lipids; instead, our data suggest that body fat may play a more important role than dietary fat in the course of cardiovascular disease development in prepubertal children.     

Subcutaneous abdominal fat and thigh muscle composition predict insulin sensitivity independently of visceral fat

Whether visceral adipose tissue has a uniquely powerful association with insulin resistance or whether subcutaneous abdominal fat shares this link has generated controversy in the area of body composition and insulin sensitivity. An additional issue is the potential role of fat deposition within skeletal muscle and the relationship with insulin resistance. To address these matters, the current study was undertaken to measure body composition, aerobic fitness, and insulin sensitivity within a cohort of sedentary healthy men (n = 26) and women (n = 28). The subjects, who ranged from lean to obese (BMI 19.6-41.0 kg/m2), underwent dual energy X-ray absorptiometry (DEXA) to measure fat-free mass (FFM) and fat mass (FM), computed tomography to measure cross-sectional abdominal subcutaneous and visceral adipose tissue, and computed tomography (CT) of mid-thigh to measure muscle cross-sectional area, muscle attenuation, and subcutaneous fat. Insulin sensitivity was measured using the glucose clamp technique (40 mU.m-2.min-1), in conjunction with [3-3H]glucose isotope dilution. Maximal aerobic power (VO2max) was determined using an incremental cycling test. Insulin-stimulated glucose disposal (Rd) ranged from 3.03 to 16.83 mg.min-1.kg-1 FFM. Rd was negatively correlated with FM (r = -0.58), visceral fat (r = -0.52), subcutaneous abdominal fat (r = -0.61), and thigh fat (r = -0.38) and positively correlated with muscle attenuation (r = 0.48) and VO2max (r = 0.26, P < 0.05). In addition to manifesting the strongest simple correlation with insulin sensitivity, in stepwise multiple regression, subcutaneous abdominal fat retained significance after adjusting for visceral fat, while the converse was not found. Muscle attenuation contributed independent significance to multiple regression models of body composition and insulin sensitivity, and in analysis of obese subjects, muscle attenuation was the strongest single correlate of insulin resistance. In summary, as a component of central adiposity, subcutaneous abdominal fat has as strong an association with insulin resistance as visceral fat, and altered muscle composition, suggestive of increased fat content, is an important independent marker of insulin resistance in obesity.     

Typical complications and their control after restorative proctocolectomy

The overall rate of complications after ileal pouch-anal anastomosis is 60%. This rate, however, includes complications such as bowel-obstruction and hernias. Pouch-related complications occur after ileal pouch-anal anastomosis with a frequency of 15-25%. In an analysis of the recent literature the main risk factors are: tension of the ileal pouch-anal anastomosis, anastomotic leakage, lack of protective ileostomy, preoperatively undiagnosed Crohn's disease and the experience of the surgeon. We classified pouch related-complications into (1) surgical complications (leakage, bleeding, pelvic sepsis, fistulas); (2) technical problems (long S-pouch spout, rectal cuff stenosis, etc.); (3) functional problems (anal sphincter insufficiency, night incontinence, hypermotility, evacuation disorders); (4) pouchitis; (5) pouch neoplasias. Pathogenesis, diagnostic features, and medical and surgical therapy are discussed in detail. In our own series of 11 pouch-redo operations we had 6 pouch fistulas (3 related to Crohn's disease, 3 postoperative fistulas), 3 wrongly constructed pouches, 1 chronic pouchitis and 1 long S-pouch spout. In 3 cases the pouch had to be excised completely. Two patients remained with a permanent ileostomy. In 6 patients the pouch could be preserved on long term. Due to the technical complexity, the need to understand pathophysiology and the need for a differentiated diagnostic procedure, this operation should be performed only in specialised centers.     

The effect of abdominal wall morphology on ultrasonic pulse distortion. Part I. Measurements

The relative importance of the fat and muscle layers of the human abdominal wall in producing ultrasonic wavefront distortion was assessed by means of direct measurements. Specimens employed included six whole abdominal wall specimens and twelve partial specimens obtained by dividing each whole specimen into a fat and a muscle layer. In the measurement technique employed, a hemispheric transducer transmitted a 3.75-MHz ultrasonic pulse through a tissue section. The received wavefront was measured by a linear array translated in the elevation direction to synthesize a two-dimensional aperture. Insertion loss was also measured at various locations on each specimen. Differences in arrival time and energy level between the measured waveforms and computed references that account for geometric delay and spreading were calculated. After correction for the effects of geometry, the received waveforms were synthetically focused. The characteristics of the distortion produced by each specimen and the quality of the resulting focus were analyzed and compared. The measurements show that muscle produces greater arrival time distortion than fat while fat produces greater energy level distortion than muscle, but that the distortion produced by the entire abdominal wall is not equivalent to a simple combination of distortion effects produced by the layers. The results also indicate that both fat and muscle layers contribute significantly to the distortion of ultrasonic beams by the abdominal wall. However, the spatial characteristics of the distortion produced by fat and muscle layers differ substantially. Distortion produced by muscle layers, as well as focal images aberrated by muscle layers, show considerable anisotropy associated with muscle fiber orientation. Distortion produced by fat layers shows smaller-scale, granular structure associated with scattering from the septa surrounding individual fat lobules. Thick layers of fat may be expected to cause poor image quality due to both scattering and bulk absorption effects, while thick muscle layers may be expected to cause focus aberration due to large arrival time fluctuations. Correction of aberrated focuses using time-shift compensation shows more complete correction for muscle sections than for fat sections, so that correction methods based on phase screen models may be more appropriate for muscle layers than for fat layers.