Extent Of Dilation Research Articles

Capillary responses to functional and pathological activations rely on the capillary states at rest

Brain capillaries play a crucial role in maintaining cellular viability and thus preventing neurodegeneration. The aim of this study was to characterize the brain capillary morphology at rest and during neural activation based on a big data analysis from three-dimensional microangiography. Neurovascular responses were measured using a genetic calcium sensor expressed in neurons and microangiography with two-photon microscopy, while neural acivity was modulated by stimulation of contralateral whiskers or by a seizure evoked by kainic acid. For whisker stimulation, 84% of the capillary sites showed no detectable diameter change. The remaining 10% and 6% were dilated and constricted, respectively. Significant differences were observed for capillaries in the diameter at rest between the locations of dilation and constriction. Even the seizures resulted in 44% of the capillaries having no detectable change in diameter, while 56% of the capillaries dilated. The extent of dilation was dependent on the diameter at rest. In conclusion, big data analysis on brain capillary morphology has identified at least two types of capillary states: capillaries with diameters that are relatively large at rest and stable over time regardless of neural activity and capillaries whose diameters are relatively small at rest and vary according to neural activity.

Pupil dilation and constriction in the skate Leucoraja erinacea in a simulated natural light field.

The skate Leucoraja erinacea has an elaborately shaped pupil, whose characteristics and functions have received little attention. The goal of our study was to investigate the pupil response in relation to natural ambient light intensities. First, we took a recently developed sensory-ecological approach, which gave us a tool for creating a controlled light environment for behavioural work: during a field survey, we collected a series of calibrated natural habitat images from the perspective of the skates' eyes. From these images, we derived a vertical illumination profile using custom-written software for quantification of the environmental light field (ELF). After collecting and analysing these natural light field data, we created an illumination set-up in the laboratory, which closely simulated the natural vertical light gradient that skates experience in the wild and tested the light responsiveness - in particular the extent of dilation - of the skate pupil to controlled changes in this simulated light field. Additionally, we measured pupillary dilation and constriction speeds. Our results confirm that the skate pupil changes from nearly circular under low light to a series of small triangular apertures under bright light. A linear regression analysis showed a trend towards smaller skates having a smaller dynamic range of pupil area (dilation versus constriction ratio around 4-fold), and larger skates showing larger ranges (around 10- to 20-fold). Dilation took longer than constriction (between 30 and 45 min for dilation; less than 20 min for constriction), and there was considerable individual variation in dilation/constriction time. We discuss our findings in terms of the visual ecology of L. erinacea and consider the importance of accurately simulating natural light fields in the laboratory.

Dilation properties of coherent Nearly-Linear models

Dilation is a puzzling phenomenon within Imprecise Probability theory: when it obtains, our uncertainty evaluation on event A is vaguer after conditioning A on B, whatever is event B in a given partition B. In this paper we investigate dilation with coherent Nearly-Linear (NL) models. These are a family of neighbourhood models, obtaining lower/upper probabilities by linear affine transformations (with barriers) of a given probability, and encompass several well-known models, such as the Pari-Mutuel Model, the ε-contamination model, the Total Variation Model, and others. We first recall results we recently obtained for conditioning NL model with the standard procedure of natural extension and separately discuss the role of the alternative regular extension. Then, we characterise dilation for coherent NL models. For their most relevant subfamily, Vertical Barrier Models (VBM), we study the coarsening property of dilation, the extent of dilation, and constriction. The results generalise existing ones established for special VBMs. As an interesting aside, we discuss in a general framework how logical (in)dependence of A from B or extreme evaluations for A influence dilation.

Long term opiate abuse and common biliary duct dilatation

Background: Acalculous common bile duct dilation secondary to chronic opioid use is a rare event that has largely only been reported in case reports. Although it is typically discovered incidentally in asymptomatic patients, it should not be ignored due to overlap with more serious hepatobiliary pathology. This especially true given the increasing use of methadone and increased risk of complications in the patients receiving this medication. Methods: Learning objectives: 1. Showcase the typical risk factors and clinical presentation of a patient with methadone-induced common bile duct dilation 2. Discuss the imaging modalities used to confirm diagnosis 3. Demonstrate the clinical importance of this finding and how it may impact future management of patients. Results: 64-year-old African American male with past medical history of HIV/AIDS hepatitis C, chronic obstructive pulmonary disease, chronic kidney disease and opioid dependence was admitted for COPD exacerbation and respiratory failure. The patient’s hospital course was complicated by sepsis. Incidentally, common bile duct dilation of 1.1 cm was discovered on CT thorax. Despite no patient complaints of nausea, vomiting, or right upper quadrant pain, the degree of dilation warranted further investigation. Laboratory studies revealed a normal bilirubin level and only mildly elevated liver enzymes. MRCP revealed bile duct dilation extending from the common bile duct into the intrahepatic ducts. Despite the extent of dilation, the patient remained asymptomatic throughout the hospital course. Conclusion: As evidenced by this case, common bile duct dilation due to chronic opioid use is typically a benign finding. However, due to the increased frequency of methadone use in patients with Hepatitis C, a diagnostic work-up is still required to rule out hepatocellular carcinoma and cirrhosis. Imaging options include endoscopic ultrasound, Endoscopic retrograde cholangiopancreatography, and Magnetic resonance cholangiopancreatography. Once a diagnosis is made, clinicians should be aware of possible complications which most notably include cholangitis secondary to biliary stasis, impaired liver function due to backflow of bile, and pancreatitis. The frequency of complications is not widely studied, but may be warranted as the use of methadone increases.

Gold nanoparticles that target degraded elastin improve imaging and rupture prediction in an AngII mediated mouse model of abdominal aortic aneurysm

Background: Abdominal aortic aneurysms (AAA) are characterized by a progressive disruption and weakening of the extracellular matrix (ECM) leading to dilation of the aorta which can be fatal if not treated. Current diagnostic imaging modalities provides little insight on the varying degree of ECM degeneration that precedes rupture in AAAs. Targeted delivery of contrast agents such as gold nanoparticles (GNPs) that bind to degraded matrix could prove useful when combined with computed tomography (CT) to provide a non-invasive surrogate marker of AAA rupture potential.Methods: AAAs were induced by chronic infusion of angiotensin II (AngII) into low density-lipoprotein receptor-deficient (LDLr -/-) mice in combination with a high-fat diet. Abdominal ultrasound was used to monitor disease progression and to assess the circumferential strain throughout the cardiac cycle. At six weeks, GNPs conjugated with an elastin antibody (EL-GNP) were injected retro-orbitally. Mice were euthanized 24 hours after EL-GNP injection, and aortas were explanted and scanned ex-vivo with a micro-CT system. Histological assessment and 3D models of the aneurysms with micro-CT were used to determine the EL-GNPs distribution. Isolated vessel burst pressure testing was performed on each aneurysmal aorta to quantify rupture strength and to assess rupture location.Results: Aneurysms were found along the suprarenal aorta in AngII infused mice. Darkfield microscopy indicated EL-GNPs accumulation around the site of degraded elastin while avoiding the healthy and intact elastin fibers. Using nonlinear regression, the micro-CT signal intensity of EL-GNPs along the suprarenal aortas correlated strongly with burst pressures (R2=0.9415) but not the dilation as assessed by ultrasound measurements.Conclusions: Using an established mouse model of AAA, we successfully demonstrated in vivo targeting of EL-GNPs to damaged aortic elastin and correlated micro-CT-based signal intensities with burst pressures. Thus, we show that this novel targeting technique can be used as a diagnostic tool to predict the degree of elastin damage and therefore rupture potential in AAAs better than the extent of dilation.

Matrimid®/polysulfone blend mixed matrix membranes containing ZIF-8 nanoparticles for high pressure stability in natural gas separation

Abstract Plasticization is of important concern in high pressure natural gas separation. Majority of the pure polymers and MOF-MMM systems suffer from plasticization at low pressures. Combination of polymer blending and MMM approach could lead to plasticization resistant membranes with improved membrane performance. In this work, the gas separation performance of Matrimid® and PSF blend membranes containing ZIF-8 nanoparticles, were studied. The effect of ZIF-8 loading on the gas transport and plasticization behavior of the blend-MOF MMMs was investigated. Gas permeability measurements of PI/PSF-ZIF-8 MMMs showed significant improvements in permeability of both CO2 and CH4, compared to pure reference polymer membrane. At a high loading of 30 wt% ZIF-8, MMM showed an enhancement of 136% in CO2 permeability compared to the pure PI/PSF membrane, while the selectivity stayed constant. This increase in the permeability could be related to the moderate increase in sorption capacity and faster diffusion of gases through the ZIF-8 nanoparticles. More detailed analysis of the gas transport performance of the MMMs showed that the CO2 permeability and the CO2/CH4 selectivity were mainly governed by the increase in CO2 diffusion coefficient. Blend MMMs were considerably more resistant to plasticization phenomenon compared to the pure PI membrane. For pure gases, native PI/PSF blend membrane showed a plasticization pressure of ∼18 bar, which increased to ∼25 bar up to 30 wt% ZIF-8 loading. Short and long CO2 exposure time experiments, with different upstream pressures, showed that the permeability stayed constant in time at pressures below the plasticization pressure while a noticeable increase in permeability was recorded in time at higher pressures. Additionally, these experiments showed that the extent of dilation in the pure PI/PSF membrane was much higher compared to the PI/PSF-ZIF-8 MMMs. In mixed gas (50/50 mol% CO2/CH4) experiments, the pure PI/PSF membrane and the MMMs did not show plasticization over the pressure range investigated, as confirmed by a constant mixed gas CH4 permeability and nearly constant selectivity with pressure. While the pure PI and PI-ZIF-8 MMMs showed the plasticization behavior. Comparing the mixed gas performance of PI/PSF-ZIF-8 membranes with that of pure PI/PSF membranes at high pressures an increase of 197% in CO2 permeability and 30% in CO2/CH4 selectivity was obtained. These results showed that the combination of polymer blending and the mixed matrix membrane approach offers a simple and economically versatile tool to approach higher CO2 permeabilities and CO2/CH4 selectivities while maintaining a stable separation performance in processes involving higher CO2 partial pressures.

Value of MR imaging in the diagnosis of intraductal papillary neoplasm of the bile duct

To analyze the value of MR imaging in diagnosis of intraductal papillary neoplasm of the bile duct (IPN-B). Fourteen patients with intraductal papillary neoplasms of the bile duct confirmed by surgical pathology were included in this study. The patients underwent MR routine plain scanning and enhancement scanning (including T1WI, T2WI with fat suppression, FALSH T1WI, and three-phase enhancement scanning), diffusion weighted imaging(DWI) and magnetic resonance cholangiopancreatography (MRCP) before operation. The imaging data were reviewed and analyzed retrospectively in comparison with the surgical and pathological results. In these patients, 7 cases had tumors located in the left lobe, 2 cases had tumors in both the left and right lobes, 2 cases in the hepatic hilum, 2 cases in the common bile duct, and 1 case in both the right lobe and the common bile duct. Solitary or multiple intraductal masses could be found in 12 cases, with 11 cases appeared as papillary masses and one case as flat mass. In the other two cases the tumor was not visible (one case had too many stones, and in another case the tumor was too small). The tumors in the 12 cases showed hypointensity on T1WI and hyperintensity on T2WI. On the dynamic contrast-enhanced MRI, 11 cases showed mild and one showed moderate enhancement in arterial phase, and all the cases showed mildly and gradually delayed enhancement. On DWI, the lesion areas showed high signal intensity in all the cases, and the ADC value of the tumor area (1.697×10(-3)mm(2)/s) was significantly lower than that of the normal bile (3.973×10(-3)mm(2)/s) (t = -10.94, P < 0.05). Twelve cases demonstrated filling defects on primary MRCP coronary thin section images. On 3D-reconstruction MRCP images, 7 cases exhibited diffuse bile duct dilatation with the tumor areas more prominent, 3 cases exhibited aneurysmal bile dilatation, while the rest 4 cases exhibited segmental or lobar bile duct dilatation ( including 2 with invisible tumors ). In the 3 cases with aneurysmal bile dilatation, the multiple directions of MRCP images helped to find the communication between the aneurysmal dilatation and the bile duct. All the cases showed significant proximal bile duct dilatation (the extent of dilatation >100%), and 9 cases also showed distal bile duct dilatation. Bile duct stones were noted in 6 cases, 4 at the tumor area, and the other 2 away from the tumor area. No adjacent tissue invasion and no distal tissue or lymph node metastasis were observed. Intraductal papillary neoplasms of the bile ducts have characteristic imaging appearances on MRI, and MRI is an important method helpful to making correct diagnosis.

The prevalence of bronchiectasis in patients with Marfan syndrome.

An association has been suggested between Marfan syndrome (MFS) and the nodular bronchiectatic form of lung disease caused by non-tuberculous mycobacteria (NTM). We evaluated the prevalence of bronchiectasis in 79 adult patients with MFS using computed tomography (CT) imaging. Airway dilation indicative of bronchiectasis (22/79, 28%) and bronchioloectasis (10/79, 13%) were relatively common, although the extent of dilation was not severe and was frequently confined to a single lobe. However, bronchiolitis was evident in only three patients (4%), and no patient was diagnosed with NTM lung disease.

Direct observation of microbubble interactions with ex vivo microvessels.

The interaction between microbubbles with tissue is poorly understood. Experimental evidence, supported by numerical simulations, suggests that bubble dynamics is highly constrained within blood vessels. To investigate this further, a high-speed microimaging system was set up to study the effects of acoustically activated microbubbles on microvessels in ex vivo rat mesentery tissues. The microbubble-perfused tissues were placed under a microscope and insonified with MHz ultrasound. A variety of interactions was observed by a high-speed camera: arterioles, venules, and capillaries were all recorded to dilate and invaginate by activated microbubbles. For small diameter microvessels, dilation and invagination were nearly symmetric, and bubble-induced rupture of the vessel was observed at high pressure. For larger microvessels, the portion of the vessel nearest the bubble coupled the strongest to the bubble dynamics, and the extent of dilation was smaller than invagination. Tissue jetting toward the bubble was recorded in many cases. The interaction of multiple bubbles inside microvessels was also observed. Bubble oscillation, vessel wall velocity, and tissue jet velocity were quantitatively measured. Invagination of vessel walls, especially tissue jetting, may be the major mechanism for tissue injury by a bubble. [Work supported by NIH 5R01EB000350.]

Measurement of Supercritical CO2 Plasticization of Poly(tetrafluoroethylene) Using a Linear Variable Differential Transformer

From measurements utilizing a linear variable differential transformer (LVDT), poly(tetrafluoroethylene) is found to undergo unusually high linear dilation in CO2 at high temperatures and pressures. The extent of dilation and the dilational profiles are shown to depend strongly on molecular weight and crystallinity. It is also shown that the conditions at which melting and sintering occur can be identified from LVDT measurements. After the first heating cycle in CO2, unsintered samples (PTFE-230, -600, -1000, and U-PTFE) show a Tm identical to PTFE (327 °C) instead of the higher pre-CO2 Tm. This observation indicates that these samples were sintered during the LVDT measurements. ΔHf was constant for pre-CO2 PTFE-230, -600, and -1000, but after sintering, crystallinity decreased with increasing molecular weight. In contrast to the precipitous drop for U-PTFE, ΔHf for PTFE-230, -600, and -1000 remained above 70 J/g. Chain entanglement effects on crystallization are modest for these low molecular weight materials. For lower molecular weight samples (PTFE-230, -600, and -1000), Tm depression and melt flow were observed. For the high molecular weight samples (PTFE and U-PTFE), Tm depression in CO2 also occurs, but exceptionally high molecular weight and chain entanglement preclude melt flow. Both PTFE and U-PTFE are unusual in that melting is signaled by an increase in dilation rather than the usual loss of shape or “slumping” due to melt flow. Despite the hydrostatic pressure effect, PTFE melting point depression in supercritical CO2 was found to be approximately 30 °C.

Implantation of Penile Prosthesis in Cases of Corporeal Fibrosis: Modified Shaeer's Excavation Technique

Implantation of penile prosthesis in case of corporeal fibrosis poses a greater risk of complications because of the blinded aggression involved. Penoscopic excavation and ultrasonography-guided excavation can decrease these complications but still have limitations. This work described the combination of penoscopy-guided and ultrasound-guided excavation in a trial to eliminate the limitations inherent to both. Twelve patients with penile fibrosis were operated upon. A guide wire was inserted under ultrasound monitoring, along which penoscopic corporotomy and resection was performed. Ultrasound was also used to monitor penoscopic excavation toward the tip of the corpus cavernosum and crus. Ease of the procedure, safety, extent of dilatation, and girth of prosthesis implanted. The procedure was relatively easy. Ten cases were dilated up to size 13.5 Hegar, and two up to size 14. Size 13 prosthesis was implanted in all cases. The relative safety of the procedure, the low incidence of complications, the possibility of restoring length and girth to an extent, and the resultant generous dilatation of the corpora for accommodating a sizable unhindered inflatable penile prosthesis all make ultrasound-guided penoscopic corporotomy and resection a valid option for prosthesis implantation in cases of penile fibrosis.

Primary Stability of Osteochondral Grafts Used in Mosaicplasty

The goal of our experiments was to determine the primary stability of osteochondral grafts used in mosaicplasty. The effect of graft diameter and dilation, as well as multiple grafting, were studied in a porcine model. Single osteochondral grafts, 4.5 and 6.5 mm in diameter, and multiple grafts were transplanted from the trochlea of porcine femurs to the weight-bearing area of the lateral femoral condyle. In the multiple grafting series, 3 grafts 4.5 mm in diameter were transplanted either in a row or in circular fashion. The grafts were first pushed in level with the surrounding cartilage surface, then they were pushed 3 mm below cartilage level. The push-in forces were measured. The effect of graft diameter and the extent of dilation on primary stability were studied as well as the influence of multiple grafting. In the case of 4.5-mm grafts, the mean level push-in force was 43.5 N, and pushing 3 mm below cartilage level required a mean of 92.5 N (n = 13). In the case of 6.5-mm grafts, level push-in required a mean of 76.2 N, and for pushing 3 mm below cartilage level a mean of 122.2 N force had to be used (n = 14). The length of the drill hole and the dilation were both 20 mm in each setting. When using 20-mm long drill holes and 15-mm dilation length, the values above were found to be 36.6 N and 122.5 N in the case of 4.5-mm grafts (n = 12). Mean level push-in force in the first (row) multiple series was 31.8 N, and pushing 3 mm below cartilage level required a mean of 52.17 N (n = 7). In the second series (circle), level push-in required a mean of 30.44 N, and for pushing 3-mm below cartilage level a mean of 54.33 N force had to be used (n = 9). In the control series (1 single graft) the mean level push-in force was 38.7 N, and pushing 3 mm deeper required a mean of 86.8 N (n = 9). These results suggest that grafts of greater diameter are more stable in absolute values and stability may be increased by shorter dilation length, whereas level push-in forces do not increase significantly. There is no difference in primary stability between grafts implanted in a row or in circular fashion, and multiple grafts may not be as stable as single grafts in the initial period after transplantation. This is a randomized, controlled in vitro animal trial that helps us to better understand the primary stability of osteochondral grafts and to refine surgical techniques as well as postoperative protocols.

Comparative study on the radiographic and CT findings of peroxyacetic acid corrosive esophagitis

目的 探讨过氧乙酸腐蚀性食管炎的X线和CT特征.方法分析7例过氧乙酸烧伤的消化道X线和CT资料.结果 7例过氧乙酸腐蚀性食管炎主要X线表现为食管中下段管腔严重不规则狭窄,管壁僵硬、蠕动消失,正常黏膜皱襞消失,狭窄以上食管呈不同程度扩张;主要CT表现为中下段狭窄区管壁呈不规则性明显增厚,密度偏低,外缘模糊,周围脂肪线消失,食管上段有不同程度扩张.结论 X线和CT检查可以清楚显示狭窄段部位、范围和程度,食管壁及周围受累情况,以指导临床制定治疗方案。

Near-surface deformation under scratches in polypropylene blends. Part I Microscopic characterization of deformation

A microstructural characterization approach has been developed to study the mechanisms of near-surface deformation under surface scratches in injection-molded polypropylene blends with over 20% rubber modifier (thermoplastic polyolefin or TPO). The near-surface microstructure of the material before and after scratching was characterized with different techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical microscopy and X-ray diffraction. It was observed that the TPO material plastically deformed by forming shear band structure under surface scratches. Materials inside shear band dilated and the extent of dilation could be measured from the characteristic angles between the shearband boundary and rubber particles. At a higher applied normal load (>200 g for the test in this study), evidence for surface fracture was observed. At even higher loads (>400 g), significant amounts of sub-surface voiding were observed, due to the delamination between the rubber phases and the polypropylene matrix. The observation of both the dilation of materials inside shearbands and the subsurface voiding at high normal loads advanced the understanding of scratching whitening mechanism in this kind of important materials. It was observed that the talc additives had no obvious influence on shear band nucleation and propagation. Results obtained in this study suggest that a strong interfacial adhesion between rubber phase and PP matrix is crucial to improving the scratching resistance of rubber modified polypropylene blends.

Dilatometric study of martensitic transformation in NiTiCu and NiTi shape memory alloys

Dilatometric measurements have been carried out for the study of nature of martensitic transformation in the NiTiCu and NiTi shape memory alloy wire samples. Investigation has been done in the heat-treat temperature range 300–800°C. NiTiCu exhibits only single stage A → M martensitic transformation in the entire heat-treat temperature range indicating the suppression of R-phase by Cu substitution. NiTi shows the two-stage A → R → M martensitic transformation in the heat-treat temperature range 340–410°C and the single-stage A → M martensitic transformation above heat-treat temperature 410°C. The extent of dilation during phase transformation decreases with increasing heat-treat temperature in both the alloys. Effect of first 15 thermal cycles on transformation temperatures in both the alloys has been studied. It is found that transformation temperatures are unaffected with thermal cycles in NiTiCu whereas considerable decrease in transformation temperatures has been observed in the case of NiTi. The stability of transformation temperatures in NiTiCu during M ↔ A transformation against thermal cycling may be attributed to the associated smaller thermal hysteresis compared to NiTi.

Cyclic Motion of Ischemic Ventricular Wall Area and Hydrodynamics of the Blood during Ejection

Analysis of dimensional changes of ischemic left ventricular wall segments evidenced a dilation immediately after onset of ejection; thereafter, contraction appears delayed but almost regular. This biphasic systolic wall motion was correlated in a retrospective study to parameters indicating local intramural disorders, intraventricular load changes, and hydrodynamics of the blood during ejection. Hemodynamic data stored on a 16-track tape recorder were analyzed from 12 consecutive experiments in anesthetized dogs in which the left circumflex coronary artery (LCX) was gradually narrowed (coronary flow restriction greater than or equal to 50%). Left ventricular and aortic pressure, aortic blood velocity (v), acceleration/deceleration (dv/dt), and instantaneous stroke volume (m = integral of v*dt), and segment lengths of normal and ischemic myocardial regions (sonomicrometry) were numerically evaluated with 5 msec resolution. Systolic shortening of the intact myocardium correlates with the diminution of the intraventricular volume during ejection (r greater than 0.98). In contrast, ischemic segments dilate early during systole when the blood is accelerated; the extent of dilation depends on the degree of coronary flow reduction. The time course of lengthening coincides with the development of force F = m*dv/dt (r greater than 0.90) originating from regularly contracting parts of the ventricle. During blood deceleration, ischemic wall segments shorten as F turns to negative (r greater than 0.95). Thus, the wall motion of ischemic myocardial regions is modulated by the hydrodynamic force resulting from acceleration and deceleration of blood consecutively impeding and supporting the systolic function of the ischemic myocardium in the course of ejection.

Vaginal birth after cesarean

The cesarean birth rate has continued to climb despite efforts to counteract this trend. A major reason for this rise is the practice of doing an elective repeat cesarean. Our study used a statistical model of meta-analysis to analyze the findings of 29 individual studies that looked at the association between the success of a trial of labor and various preexisting conditions. We hypothesized that various preexisting factors, including cephalopelvic disproportion, previous breech, previous vaginal delivery, more than one previous cesarean, use of oxytocin, and the length of labor and extent of dilatation in the previous cesarean, would affect the prediction of the outcome of a trial of labor. After determining odds ratios for the individual preexisting factors from the individual studies, we calculated overall odds ratios which incorporated the findings from all of the studies. For previous cephalopelvic disproportion, the odds were 0.5 for a successful trial of labor; for prior breech, 2.1; for women with a previous vaginal delivery, 2.1; for women who had had more than one cesarean, 0.7; and for women receiving oxytocin, 0.3. We were unable to analyze other preexisting factors because the data were not available, but short discussions of some of these other factors are offered. Even though the success rates do vary with the different preexisting factors, the clinician may anticipate a greater than 50% chance for success in any individual labor.

Diuresis Renography

In 20 patients investigated for unilateral upper urinary tract obstruction diuresis renography was performed simultaneously with 131I-hippuran and 99Tcm-MAG3 using a gamma camera with dual isotope facilities. Furosemide was administered routinely 20 min after radionuclide injection. No significant differences were found in fractional share between the two kidneys, time to maximal activity, residual activity at 20 and 30 min, or rate of emptying after furosemide administration. The MAG3 curves showed, however, better counting statistics and on scintigrams with MAG3 more anatomic details (extent of dilation and site of obstruction) could be seen. It is concluded, that MAG3 is superior to hippuran in the evaluation of patients with possible unilateral upper urinary tract obstruction by diuresis renography.

Diuresis Renography

In 20 patients investigated for unilateral upper urinary tract obstruction diuresis renography was performed simultaneously with 131I-hippuran and 99Tcm-MAG3 using a gamma camera with dual isotope facilities. Furosemide was administered routinely 20 min after radionuclide injection. No significant differences were found in fractional share between the two kidneys, time to maximal activity, residual activity at 20 and 30 min, or rate of emptying after furosemide administration. The MAG3 curves showed, however, better counting statistics and on scintigrams with MAG3 more anatomic details (extent of dilation and site of obstruction) could be seen. It is concluded, that MAG3 is superior to hippuran in the evaluation of patients with possible unilateral upper urinary tract obstruction by diuresis renography.

Investigation of the dilated urinary tract.

Dilatation of the urinary tract does not necessarily imply obstruction, and other factors may be operative: maldevelopment, infection, reflux, and polyuria. Obstruction of the urinary tract in intra-uterine life is associated with renal dysplasia: the original obstructive lesion may be transient but the consequent dysplasia and dilatation may be permanent. Routine antenatal ultrasound identifies a new population of infants with urinary tract dilatation, many of whom remain asymptomatic and would not otherwise have come to medical attention: the natural history and appropriate schedules of investigation and management of this group are still being evaluated. Anatomical imaging by ultrasound establishes the presence and extent of dilatation. Micturating cystourethrography, intravenous urography and antegrade pyelography establish the site but not the functional significance of an obstructive lesion. Isotope renal scanning with 99mTc-DTPA may identify an acutely obstructed kidney with a decrease renal uptake, prolonged parenchymal transit time, and delayed clearance of the isotope from the renal pelvis after furosemide. However, such analyses often give equivocal results in infants with poor renal function and markedly dilated urinary tracts. Obstructive uropathy should be seen as a disturbance of the normal pressure-flow relationships in the urinary tract, and be defined and investigated as such. Antegrade perfusion with renal pelvic pressure measurements has technical pitfalls, but is the definitive method of establishing upper tract obstruction. Videocystourethrography is the established method of investigating the lower urinary tract in older children but needs further development to be applicable to infants.