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M P Meza

Publications and source records attributed to M P Meza.

At least 19 recordsLinked to original sources
PubMed2001

MRCP in the evaluation of pancreaticobiliary disease in children.

BACKGROUND: Radiologic assessment of pancreaticobiliary ductal disease (PBDD) in children currently consists of physiologic tests (radionuclide examinations) or invasive anatomic studies (ERCP and PTC). An accurate noninvasive and reproducible examination that can direct the subsequent need for more invasive studies would be helpful in this patient group. OBJECTIVE: To determine the effectiveness of MRCP as a screening tool for PBBD in the pediatric population. MATERIALS AND METHODS: Over the last year, 33 patients ranging from 7 months to 20 years of age were prospectively evaluated with MRCP on a 1.5 T magnet. One patient was examined twice, several months apart. Thirteen patients had liver transplants. Coronal SPGR and heavily T-2W FSE cross-sectional images were obtained. Standard and oblique 2- to 6-cm-thick slab SSFSE (single-shot fast spin echo) acquisition and 3D MIP reconstruction of 2D FSE images were obtained in the planes of the CBD and pancreatic duct. Nine studies were performed with the patient under sedation with chloral hydrate or nembutal and fentanyl with quiet respiration, and the non-sedated patients were assessed with single breath hold or quiet respiration. Three patients received secretin. MRCP results were correlated with ERCP (9), PTC (7), liver biopsy (13), clinical information (6), surgery (3), and autopsy (2). RESULTS: All 34 studies performed were considered diagnostic. Periportal fluid, proximal bowel fluid, and gallbladder distention did not significantly diminish the diagnostic information in any cases. Motion artifact did not cause serious degradation in image quality. MRCP depicted abnormalities including stones, stricture, intraductal tumor, and extrinsic compression, all of which were confirmed at ERCP, PTC ( two unsuccessful in patients with non-dilated ducts by MRCP), surgery, liver biopsy, and autopsy. There were no false-negative examinations. Normal pancreatic studies performed to exclude pancreas divisum were followed without additional clinical or laboratory evidence of pancreatitis. Secretin administration increased the conspicuity of the pancreatic duct in two of three patients. CONCLUSION: MRCP is a fast non-invasive method of evaluating the pancreatic duct and biliary tree in children. A normal MRCP may obviate the need for PTC or ERCP. Abnormalities detected on MRCP can direct the type of intervention.

Adolescent↗
PubMed2000

Intrahepatic chemoembolization in unresectable pediatric liver malignancies.

OBJECTIVE: To determine the effectiveness of a new multidisciplinary approach using neoadjuvant intrahepatic chemoembolization (IHCE) and liver transplant (OLTx) in patients with unresectable hepatic tumors who have failed systemic chemotherapy. MATERIALS AND METHODS: From November 1989 to April 1998, 14 children (2-15 years old) were treated with 50 courses of intra-arterial chemotherapy. Baseline and post-treatment contrast-enhanced CT and alpha-fetoprotein levels were performed. Seven had hepatoblastoma, and 7 had hepatocellular carcinoma (1 fibrolamellar variant). All patients had subselective hepatic angiography and infusion of cisplatin and/or adriamycin (36 courses were followed by gelfoam embolization). The procedure was repeated every 3-4 weeks based on hepatic function and patency of the hepatic artery. RESULTS: Six of 14 children received orthotopic liver transplants (31 courses of IHC). Pretransplant, 3 of 6 showed a significant decrease in alpha-fetoprotein, while only 1 demonstrated a significant further reduction in tumor size). Three of 6 patients are disease free at this time. Three of 6 patients died of metastatic tumor 6, 38, and 58 months, respectively post-transplant. One of 14 is currently undergoing treatment, has demonstrated a positive response, and is awaiting OLTx. Three of 14 withdrew from the program and died. Four of 14 patients developed an increase in tumor size, developed metastatic disease, and were not transplant candidates. Two hepatic arteries thrombosed, and one child had a small sealed-off gastric ulcer as complications of intrahepatic chemoembolization. CONCLUSION: The results of intrahepatic chemoembolization are promising and suggest that some children who do not respond to systemic therapy can be eventually cured by a combination of intrahepatic chemoembolization orthotopic liver transplant. Alpha-fetoprotein and cross-sectional imaging appear to be complementary in evaluating tumor response. IHCE does not appear to convert an anatomically unresectable lesion to a candidate for partial hepatectomy.

Adolescent↗
PubMed1999

Hyperbaric oxygen therapy for hepatic artery thrombosis after liver transplantation in children.

Early hepatic artery thrombosis (HAT) after pediatric orthotopic liver transplantation (OLT) can cause significant morbidity and mortality, leading to liver failure or septic complications requiring urgent retransplantation. Experimental evidence that hyperbaric oxygen (HBO) may ameliorate hepatic ischemic-reperfusion injury led to this study of HBO in pediatric liver transplant recipients who developed HAT. Children undergoing OLT under primary tacrolimus immunosuppression and University of Wisconsin organ preservation between August 1, 1989, and December 31, 1998, who developed HAT were the basis for this study. Patients who developed HAT between March 1, 1994, and December 31, 1998, were treated with HBO therapy until signs of ischemia resolved (absence of fever, normalizing liver injury test results) or for 2 weeks. The pediatric OLTs performed from August 1, 1989, to February 28, 1994, who developed HAT served as a control group. Primary outcome measures were survival, retransplantation rate, time to retransplantation, incidence of hepatic gangrene, and days to collateral formation. Three hundred seventy-five consecutive pediatric patients underwent 416 OLTs between August 1, 1989, and December 31, 1998. Thirty-one patients (7.5%) developed HAT at a mean time of 8.2 days (range, 1 to 52 days) post-OLT. In 17 patients, HBO treatment was begun within 24 hours of HAT or immediately after the revascularization attempt and performed twice daily for 90 minutes at 2.4 atmospheres pressure. Fourteen patients were treated without HBO. None of the HBO-treated patients developed hepatic gangrene. Eight HBO patients (47%) were bridged to retransplantation at a mean time of 157 days (range, 3 to 952 days) after initial OLT and all survived. Mean time to retransplant in the control group was 12.7 days (range, 1 to 64 days). HBO was well tolerated without significant complications. Although there was no significant difference in survival or retransplantation rates, HBO significantly delayed retransplantation, potentially by hastening the development of hepatic artery collaterals.

Arterial Occlusive Diseases↗
PubMed1999

Insulin sensitivity in African-American children with and without family history of type 2 diabetes.

OBJECTIVE: African-Americans are at increased risk for type 2 diabetes. We have previously demonstrated that African-American children are hyperinsulinemic and insulin resistant compared with their white American peers. The aim of the present investigation was to assess the impact of family history of type 2 diabetes on insulin sensitivity in African-American children. RESEARCH DESIGN AND METHODS: A total of 13 prepubertal healthy children with negative family history (FH-) and 9 with positive family history (FH+) of type 2 diabetes underwent a 3-h hyperinsulinemic (40 mU x m(-2) x min(-1))-euglycemic clamp study to assess insulin sensitivity. The groups were comparable for age, pubertal status, total body adiposity determined by dual-energy X-ray absorptiometry, abdominal adiposity assessed by computed tomography scan at the level of L4-5 lumbar vertebra, and physical fitness measured by maximal oxygen consumption (VO2max). RESULTS: The FH+, compared with the FH-, group had lower insulin-stimulated glucose disposal (10.9+/-1.2 vs. 14.2+/-0.9 mg x kg(-1) x min(-1), P = 0.035) and lower nonoxidative glucose disposal (5.7+/-0.8 vs. 8.3+/-0.6 mg x kg(-1) x min(-1), P = 0.015), with no differences in rates of glucose oxidation, fat oxidation, or insulin-mediated free fatty acid suppression. Fasting hepatic glucose production assessed with [6,6-2H2]glucose and basal rates of glucose and fat oxidation were not different between the two groups. CONCLUSIONS: These data suggest that in African-American children, family history of type 2 diabetes is a risk factor for insulin resistance. These children manifest important metabolic alterations, including impaired insulin-stimulated total and nonoxidative glucose disposal early in the first decade of life. We propose that this familial tendency, combined with environmental influences, could lead to type 2 diabetes decades later.

Basal Metabolism↗
PubMed1998

Left mainstem bronchial narrowing: a vascular compression syndrome? Evaluation by magnetic resonance imaging.

BACKGROUND AND OBJECTIVE: Vascular compression of the left mainstem bronchus (LMSB) between the descending aorta (DA) and pulmonary artery (PA) has been suggested as a cause for LMSB narrowing in children. These anatomic relationships have not been compared with those in children with a normal LMSB. Materials and methods. We undertook a retrospective review of the medical and radiologic records of 10 symptomatic young children (1-19 months, 5 boys, 5 girls) with MR demonstration of LMSB narrowing and compared them to 40 young children without great vessel or bronchial abnormality on MR (1 week-19 months, 28 boys, 12 girls). Chest MR evaluation included assessment of airway and great vessel anatomy with specific attention to the course of the LMSB and its relationship to the adjacent DA and PA. The position of the DA in relation to the spine was carefully evaluated. RESULTS: Five children had focal and five had diffuse LMSB narrowing. DA position at the level of the crossing LMSB: in 40% of symptomatic children the DA was located in front of the adjacent vertebral body; in 40%, 1/2-3/4 and in 20% 1/4-1/2 of the circumference of the DA was located anterior to the spine. In the control group, the DA was prespinal in 10%, with a trend toward a more paraspinal location of the DA. The trend toward a difference in position of the DA between symptomatic and control patients was statistically significant (P < 0.05). DA position was not related to age (up to 19 months). At the level where the LMSB crossed the DA, a segment of the PA was located anterior to the LMSB, more often the right PA (RPA) or pulmonary bifurcation in symptomatic children and the left PA (LPA) in controls. No correlation was apparent between length of LMSB narrowing and DA or PA position. Chest radiographic abnormalities, when present, were subtle. Excellent MR/bronchoscopic correlation of LMSB narrowing was found in nine of the ten symptomatic children. One child underwent posterior aortopexy and ligation of the ligamentum arteriosum. CONCLUSION: LMSB narrowing is well-defined by MR imaging. While a prespinal position of the DA occurs in some children as a normal variant, it is more common and more marked in children with LMSB narrowing. Vascular compression of the LMSB between an anteriorly positioned DA and the pulmonary artery appears to be important in children with symptomatic LMSB narrowing.

Aorta, Thoracic↗
PubMed1997

Magnetic resonance imaging of the pediatric airway.

OBJECTIVE: To determine the role of magnetic resonance imaging (MRI) and how it relates to endoscopy as well as to other imaging modalities in the evaluation of pediatric airway disorders. DESIGN: A review study of children with various distal airway disorders over a 3-year period. Surgical procedures as well as all diagnostic imaging modalities were reviewed and analyzed with respect to clinical outcome. SETTING: Academic tertiary care children's hospitals. PATIENTS: Forty-nine children between the ages of 1 week and 14 years with the signs and symptoms of distal airway disorders. INTERVENTIONS: Forty-five of 49 children underwent airway endoscopy. Fourteen children also underwent fluoroscopy and 4 underwent echocardiography. When indicated, open surgical repair was performed and used to verify findings in 32 cases. RESULTS: Magnetic resonance imaging was the most accurate modality in defining extrinsic airway abnormalities. The findings of echocardiography were incorrect in 2 of 4 cases, and fluoroscopy, although accurate for tracheal narrowing and tracheomalacia, often could not elucidate that exact cause or missed left mainstem bronchial compression. Furthermore, tracheal narrowing to 50% or greater on MRI correlated 100% with the need for surgical intervention. CONCLUSIONS: Magnetic resonance imaging is a useful modality that has allowed us to accurately diagnose extrinsic pediatric tracheal abnormalities. In certain cases, MRI scans can be obtained prior to endoscopy. In those cases, definitive endoscopy and open repair are performed at the same procedure instead of at 2 separate procedures (ie, one for diagnostic endoscopy and the other for definitive repair).

Adolescent↗
PubMed1997

Thoracic neuroblastoma: what is the best imaging modality for evaluating extent of disease?

BACKGROUND: Thoracic neuroblastoma accounts for 15% of all cases of neuroblastoma. A minority of children with thoracic neuroblastoma will have dumbbell tumors, i.e., intraspinal extension, but only half these patients will have neurologic signs or symptoms. HYPOTHESIS: MR imaging is the single best test to evaluate the extent of thoracic and spinal disease in thoracic neuroblastoma after the diagnosis of a mass is established on plain film. MATERIALS AND METHODS: A retrospective multi-institutional investigation over 7 years of all cases of thoracic neuroblastoma (n = 26) imaged with CT and/or MR were reviewed for detection of the extent of disease. The chest film, nuclear bone scan, and other imaging modalities were also reviewed. The surgical and histologic correlation in each case, as well as the patients' staging and outcome, were tabulated. RESULTS: The chest radiograph was 100% sensitive in suggesting the diagnosis. MR imaging was 100% sensitive in predicting enlarged lymph nodes, intraspinal extension, and chest wall involvement. CT was 88% sensitive for intraspinal extension but only 20% sensitive for lymph node enlargement. CT was 100% sensitive in detecting chest wall involvement. Direct comparison of CT and MR imaging in six cases revealed no difference in detection of enlarged lymph nodes or chest wall involvement. Neither test was able to detect remote disease, as noted by bone scan. CONCLUSION: The chest film is 100% sensitive in suggesting the diagnosis of thoracic neuroblastoma; MR imaging appears to be the single best test for detecting nodal involvement, intraspinal extension, and chest wall involvement.

Adolescent↗
PubMed1997

Computed tomography grade of splenic injury is predictive of the time required for radiographic healing.

It is largely unknown when a child who has suffered a splenic laceration can return to full unrestricted activity. The purpose of this prospective study is to establish whether the grade of splenic injury is predictive of the length of time required for radiographic healing, and to determine whether there are any adverse long-term sequelae after resumption of unlimited activity. Sixty-nine patients underwent successful nonoperative management (NOM) of computed tomography (CT)-documented splenic injury over a 4-year period. Fifty-eight patients completed follow-up. Mean age was 9.8 years (range, 1 to 17) and mean injury severity score (ISS) was 14.4 (range, 4 to 38). Mechanisms of injury were motor vehicle accident (n = 11), motor vehicle pedestrian (n = 5), falls (n = 13), bike crashes (n = 12), sports (n = 8), all-terrain vehicle (n = 4), and horse (n = 5). The CT-documented injury was identified by discharge ultrasound scan (US) in all cases. There were no long-term complications. Mean time to US healing in grade I (n = 9), II (n = 26), III (n = 19), IV (n = 4) injuries was 3.1, 8.2, 12.1, and 20.7 weeks, respectively. P values were significant (P < .01) in all cases when compared with the next lower injury grade. The time to radiographic healing is directly proportional to the severity of the splenic injury. There was excellent correlation between the initial CT scan and identification of the injury on the discharge US. No long-term complications leg, delayed splenic rupture, splenic pseudocyst) were seen in this study. Pediatric patients who have suffered splenic injury can safely return to full unrestricted activity when the US documents healing.

Adolescent↗
PubMed1997

Management of blunt splenic trauma: significant differences between adults and children.

BACKGROUND: Although highly successful in children, nonoperative management of blunt splenic injury in adults is less defined. The purpose of this study was to determine whether mechanism of injury, grade of splenic injury, associated injuries, and pattern of injury differ between adults and children (younger than 15 years of age). METHODS: Four hundred eleven patients (293 adults and 118 pediatric patients) with blunt splenic injury were admitted to an affiliated adult/pediatric trauma program from 1989 to 1994. Computed tomography (CT) scans were interpreted in a blinded fashion. Mechanism of injury was significantly different for adults versus children (p < 0.05): motor vehicle crash (66.9% versus 23.7%), motorcycle (8.8% versus 0.8%), sports (2.4% versus 16.9%), falls (8.8% versus 25.4%), pedestrian/automobile (4.4% versus 11.0%), bicycle (1.4% versus 9.3%), and other (7.3% versus 12.7%). RESULTS: Higher injury severity scores, lower Glasgow Coma Scales, and higher mortality indicated that the adults were more severely injured than the children. Fifty-nine percent of the adults and 7% of the children required immediate laparotomy for splenic injury. Both CT grade and quantity of blood on CT predicted the need for exploration in adults but not in children. An injury severity score above 15 and high-energy mechanisms correlated with the need for operative intervention. CONCLUSIONS: Rather than children simply being physically different, they are injured differently than adults, hence the high rate of nonoperative management.

Accidents, Traffic↗
PubMed1997

Diagnosis and management of left main stem bronchus compression.

There are four major variants of congenital vascular tracheal compression: innominate artery, aberrant subclavian, aorta or aortic arch anomaly, and pulmonary artery sling. These forms of vascular compression typically involve the trachea and/or the right main stem bronchus. We present eight cases of congenital vascular compression involving the left main stem bronchus. These cases represent a poorly understood variant of vascular tracheal compression. This variant represents approximately 10% of our pediatric tracheobronchial compression or stenosis patients. The finding, both noted endoscopically and now illustrated by magnetic resonance imaging, is caused by compression of the left main stem bronchus between the descending aorta and a portion of the pulmonary artery. Frequently, the descending aorta is in an abnormal anterior position with relation to the thoracic spine. Recognition of this entity is important in our experience and has influenced clinical management. In four of eight children, it required a surgical procedure directed toward the relief of the left main stem compression.

Abnormalities, Multiple↗
PubMed1996

Left pulmonary artery sling: diagnosis and delineation of associated tracheobronchial anomalies with MR.

BACKGROUND: The left pulmonary artery sling anomaly (SLPA) has generated controversy about its diagnosis, imaging and management particularly with regard to associated tracheobronchial anomalies. Objective. To evaluate the role of MR imaging in defining airway and vascular relationships in SLPA. MATERIALS AND METHODS: Retrospective review of the imaging and clinical records of three children with SLPA who underwent MRI including three dimensional image reconstruction. MR was compared and correlated with other imaging methods: plain chest radiographs (3); bronchoscopy (3); barium esophagram (1); echocardiography (2); cineangiography (2). RESULTS: MRI was vastly superior to other methods for clearly depicting airway and vascular anatomy and interrelationships. Good quality imaging and safe sedation was easily achieved in young infants. MR also provided accurate noninvasive evaluation of the reconstructed pulmonary artery and airway postoperatively. CONCLUSION: MR is capable of differentiating the two subtypes of SLPA. Specific delineation of vascular and airway anatomy and spatial relationships is essential for surgical management: reimplantation of LPA in type I and both LPA reimplantation and airway reconstruction in type II because of associated long segment airway stenosis.

Airway Obstruction↗
PubMed1996

Perflubron as a gastrointestinal MR imaging contrast agent in the pediatric population.

OBJECTIVE: To evaluate the safety and efficacy of orally administered perflubron for bowel recognition on MR imaging in a pediatric population. MATERIALS AND METHODS: A multicenter trial evaluated 39 pediatric subjects before and after ingestion of perflubron with T1-, proton-density, and T2-weighted sequences through the abdomen and/or pelvis. Post-contrast images were compared with pre-contrast images. Safety was evaluated through assessment of adverse events, clinical laboratory parameters, and vital signs. RESULTS: With regard to efficacy analysis, improvement in the percent of bowel darkened was observed for 85 % of the subjects on T1-weighted images and for 95 % of the subjects on proton-density and T2-weighted images. For images of the abdominal region, the percent of bowel darkened was improved for 90-92 % of the subjects across pulse sequences. Improvement rates for the images of the pelvic region ranged from 71 % to 100 %. For at least 75 % of the subjects, proton-density and T2-weighted images of the body and tail of the pancreas, left lobe of the liver, mesenteric fat, and pathological tissue were improved relative to predosing images. Twenty-three percent of the subjects experienced some adverse effects, most of which were minor and related to the digestive system. Clinical laboratory and vital sign evaluations revealed no trends associated with the administration of perflubron. CONCLUSION: Perflubron is a relatively safe and effective gastrointestinal MR contrast agent in the pediatric population.

Abdomen↗
PubMed1996

Intestinal stricture following seat belt injury in children.

The most commonly reported intestinal injury from seat belts in children is perforation. A rarely reported late sequela following this type of injury is posttraumatic intestinal stricture (PTIS). A review of the literature reveals a common clinical pattern of presentation in children and adults but an apparent difference in the pathophysiologic mechanism between the pediatric and adult patient. Recently, we treated two children with PTIS. Each case is discussed, and a pathophysiological mechanism for this injury in children is proposed. Recommendations are made for the evaluation and treatment of these uncommon complications of seat belt-related blunt intestinal injury.

Adult↗
PubMed1996

Is computed tomography a useful adjunct to the clinical examination for the diagnosis of pediatric gastrointestinal perforation from blunt abdominal trauma in children?

Perforations of the gastrointestinal (GI) tract, compared to solid organ injuries, are a relatively infrequent sequela of blunt abdominal trauma in children. The purpose of this study is to review retrospectively the diagnostic modalities used in 30 children with proven traumatic intestinal perforations treated at one institution. Since computed tomography with intravenous and oral GI contrast is commonly used in the diagnosis of suspected solid organ injury from blunt abdominal trauma, we evaluated retrospectively the computed tomographic (CT) scan findings in these children in an attempt to accurately predict or suggest GI perforation. Between January 1987 and December 1993, 5,795 children were admitted. Three hundred fifty suffered blunt abdominal trauma of which 30 patients (8.5%) required surgery for a GI perforation and formed the basis for this study. Data collected were mechanisms of injury, results of admission and serial clinical examinations, results of radiologic imaging, associated injuries, operative findings, and outcome. Follow-up was obtained on all patients and averaged 2.5 years. Blows to the abdomen (handlebars, cars, kicks) were the most common cause of perforation, followed by seatbelt injuries. Eleven patients underwent immediate laparotomy an average of 0.75 hours after admission. The indication for surgery was shock (three), clinically apparent peritonitis (five), and free air on plain abdominal radiograph (three). Nineteen patients underwent "later" laparotomy, an average of 3.4 hours after admission, all because of the eventual development of peritonitis. Retrospective review of these CT scans revealed free air anterior to the liver in three, and the remaining 16 had CT findings suggestive of GI injury such as free fluid, focal fluid-filled thick-walled bowel loops, and mesenteric infiltration. There were five (26%) false negative CT scans performed an average of 5.0 hours after injury. We believe serial physical examinations are the gold standard for diagnosing pediatric GI perforation from blunt abdominal trauma. The CT scan may be a useful adjunct to the diagnosis of an intestinal perforation in patients who have no immediate indication for surgery. Presently, the only CT finding that is an absolute indication for laparotomy is free air (in the absence of pulmonary/mediastinal injury or barotrauma). The other CT "findings" need to be validated prospectively.

Abdominal Injuries↗
PubMed1996

Direct injury to the cervical spine of a child by a lap-shoulder belt resulting in quadriplegia: case report.

Most pediatric cervical spine injuries from seat-belt restraints result from hyperflexion of the neck without direct injury to the spine from the restraining device. We report what we believe to be the first case of direct injury to the cervical spine by the shoulder component of a lap-shoulder seat belt. This resulted in quadriplegia. The mechanism of injury and recommendations to obviate such injuries are discussed.

Accidents, Traffic↗
PubMed1995

Osteoid osteoma: percutaneous excision using a CT-guided coaxial technique.

OBJECTIVE: We describe a coaxial technique for percutaneous, CT-guided removal of osteoid osteoma in children. SUBJECTS AND METHODS: The study included eight children aged 3 years to 15 years 9 months who had signs and symptoms of osteoid osteoma. The diagnoses were confirmed by CT scans. Seven of nine lesions were removed manually with a coaxial technique and a trephine. Power tools were added to the technique in the other two cases. Removal of the nidus was confirmed by postprocedural CT scans and by histologic examination. RESULTS: All CT-guided excisions were technically successful, and only one minor complication occurred. One recurrence at 13 months was successfully treated percutaneously. CONCLUSION: CT-guided coaxial removal of osteoid osteoma is a safe and effective treatment. Increasing experience and the use of power tools in selected cases helps to shorten the procedure.

Adolescent↗
PubMed1993

Imaging of mediastinal masses in children.

Conventional radiographs show the mediastinum to be the most frequent location of thoracic masses in children. The compartmental approach to evaluation of pediatric mediastinal masses is advised. Compartmental localization and lesion internal characteristics are best determined by cross-sectional imaging techniques. These techniques as well as the causes and significance of the common pediatric mediastinal masses are discussed. Imaging of the thymus is emphasized because normal thymic tissue can mimic pathologic conditions and the thymus is a common thoracic location for neoplasms in children.

Child↗