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PubMedDate not supplied

[Hydrodynamic and biochemical adaptation to perfusion pressure profile in isolated hypothermic renal perfusion].

OBJECTIVES: To evaluate hydrodynamic, biochemical and pathologic consequences of positive forced pressure on hypothermic isolated renal perfusions in comparison to softly progressive administration of perfusion solution. MATERIAL AND METHOD: 16 hypothermic experimental pig renal perfusion o 180 min completed under constant flow conditions. A vacuum computer-controlled pump was used. A comparison was performed of the results obtained by two groups of organs (forced perfusion pressure -I.B.- and soft perfusion pressure -I.S.). RESULTS: Even though perfusion flor did not offer significant differences among both groups at the end of the procedure, I.B. group showed medium perfusion pressure and renal vascular resistance values significantly higher. Nitric oxide metabolites concentration was also greater in I.B. group. Finally, these kidneys showed more tubular cell aedema and glomerular shrinkage in comparison to I.S. group. CONCLUSIONS: Sharp and forced hypothermic perfusion of the isolated kidney don't increase flow perfusion values. Inversely, hydrodynamic and pathologic results are worst in comparison to soft and progressive organ perfusion.

Adaptation, Physiological↗
PubMedDate not supplied

High prevalence of asymptomatically poor muscle perfusion of lower extremities measured in type II diabetes patients with abnormal myocardial perfusion.

Foot problems are the most common cause of hospital admission in patients with type II diabetes mellitus (DM). Poor muscle perfusion of lower extremities is thought to be the major component in the pathogenesis of foot problems. Therefore, it is important and interesting to investigate if high prevalence of poor muscle perfusion of lower extremities in type II DM patients with abnormal myocardial perfusion and more cardiovascular risk factors. We used a well-established and noninvasive radionuclide method (Xe-133 muscle washout) to objectively evaluate the anterior tibial muscle perfusion of 60 type II DM male patients without symptoms/signs of peripheral vascular disease (PVD) in the lower extremities. The patients were separated into groups according to the myocardial perfusion imaging results and cardiovascular risk factor survey. Meanwhile, 30 normal male controls with a matched age distribution were also included for comparison. The muscle perfusions were of significant difference (P-values <.05) between (1) 60 type II DM patients (1.84+/-0.43 ml/100 g/min) and 30 normal controls (2.95+/-0.52 ml/100 g/min), (2) 24 patients with abnormal myocardial perfusion (1.31+/-0.45 ml/100 g/min) and 36 patients with normal myocardial perfusion (2.24+/-0.48 ml/100 g/min), as well as (3) 28 patients with more cardiovascular risk factors (1.33+/-0.46 ml/100 g/min) and 22 patient with less cardiovascular risk factors (2.22+/-0.49 ml/100 g/min). Based on Xe-133 muscle washout method, we concluded that the muscle perfusion in the lower extremities of type II DM patients without symptoms/signs of PVD is significantly decreased and related to abnormal myocardial perfusion and more cardiovascular risk factors.

Aged↗
PubMed2006

Pulmonary perfusion in acute pulmonary embolism: agreement of MRI and SPECT for lobar, segmental and subsegmental perfusion defects.

PURPOSE: To assess prospectively the agreement of magnetic resonance (MR) pulmonary perfusion with single-photon emission computed tomography (SPECT) perfusion for perfusion defects down to the subsegmental level in patients with suspected pulmonary embolism (PE). MATERIAL AND METHODS: In 41 patients with suspected PE, contrast-enhanced MR pulmonary perfusion (3D-FLASH, TR/TE 1.6/0.6 ms) was compared to SPECT perfusion on a per-examination basis as well as at the lobar, segmental, and subsegmental level. RESULTS: The MRI protocol was completed in all patients, and mean examination time was 3 min 56 s. MR perfusion showed a very high agreement with SPECT (kappa value per examination 0.98, and 0.98, 0.83, and 0.69 for lobar, segmental, and subsegmental perfusion defects, respectively). Of 15 patients with PE, MR perfusion detected 14 cases. CONCLUSION: The very high agreement of MR perfusion with SPECT perfusion enables the detection of subtle findings in suspected PE.

Acute Disease↗
PubMedDate not supplied

Multiphasic perfusion computed tomography in hyperacute ischemic stroke: comparison with diffusion and perfusion magnetic resonance imaging.

PURPOSE: The purpose of this study was to compare multiphasic perfusion computed tomography (CT) with diffusion and perfusion magnetic resonance imaging (MRI) in predicting final infarct volume, infarct growth, and clinical severity in patients with hyperacute ischemia untreated by thrombolytic therapy. METHOD: Multiphasic perfusion CT was performed in 19 patients with ischemic stroke within 6 hours of symptom onset. Two CT maps of peak and total perfusion were generated from CT data. Diffusion-weighted imaging (DWI) and perfusion MRI were obtained within 150 minutes after CT. Lesion volumes on CT and MRI were compared with final infarct volume and clinical scores, and mismatch on CT or MRI was compared with infarct growth. RESULTS: The lesion volume on the CT total perfusion map strongly correlated with MRI relative cerebral blood volume (rCBV), and that on the CT peak perfusion map strongly correlated with MRI relative cerebral blood flow (rCBF) and rCBV (P < 0.001). The lesion volume on unenhanced CT or DWI moderately correlated with final infarct volume, but only lesion volume on unenhanced CT weakly correlated with baseline clinical scores (P = 0.024). The lesion volumes on the CT peak perfusion map and MRI rCBF similarly correlated with final infarct volume and clinical scores and more strongly than those on mean transit time (MTT) or time to peak (TTP). DWI-rCBF or CT mismatch was more predictive of infarct growth than DWI-MTT or DWI-TTP mismatch. CONCLUSION: Multiphasic perfusion CT is useful and of comparable utility to diffusion and perfusion MRI for predicting final infarct volume, infarct growth, and clinical severity in acute ischemic stroke.

Acute Disease↗
PubMed1994

The effects of perfusion rate and NG-nitro-L-arginine methyl ester on cirazoline- and KCl-induced responses in the perfused mesenteric arterial bed of rats.

1. The purpose of this study was to characterize the effect of NG-nitro-L-arginine methyl ester (L-NAME) on the perfusion rate/pressure relations, and on the pressor responses induced to cirazoline and KCl in isolated, perfused mesenteric arterial beds from normotensive and spontaneously hypertensive rats. 2. The basal perfusion pressure of arterial beds perfused with either physiological salt solution (PSS) or PSS containing 1% polyvinylpyrrolidone increased as the perfusion rate increased. L-NAME, in concentrations up to 100 microM, failed to alter the basal pressure regardless of the perfusion rate and viscosity; however, at 5 microM, it potentiated cirazoline-induced vasoconstriction at each of the perfusion rates. 3. L-NAME but not D-NAME caused a leftward shift of cirazoline concentration-response curves with a marked increase in the maximal response. The potentiating action of L-NAME was abolished in arterial beds perfused with a Ca(2+)-free physiological salt solution and also in beds denuded of endothelium by an infusion of distilled water for 5 min. 4. In endothelium-intact and -denuded preparations, L-NAME potentiated KCl pressor responses; the endothelium-independent potentiation of KCl pressor activity was stereospecific, time-independent and was not prevented by the presence of dexamethasone (0.5 microM) in the perfusion medium. However, L-NAME failed to potentiate vasoconstriction obtained to KCl in arterial beds denervated by cold storage (4-5 degrees C) for 2 days. 5. The absence of K+ in the perfusate did not inhibit the ability of L-NAME to potentiate alpha-adrenoceptor-mediated pressor responses, and nor did L-NAME inhibit KCl-induced vasodilatation in preconstricted arteries. It was thus concluded that L-NAME does not affect Na+/K(+)-ATPase activity. 6. No differences in the potentiating ability of L-NAME on either cirazoline- or KCl-mediated pressor responses were apparent between normotensive Sprague Dawley (SD), Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats.7. Our data thus provide evidence that: the presence of a vasoconstrictor is required for basal nitricoxide (NO) release in the mesenteric arterial bed from either normotensive or spontaneously hypertensive rats; L-NAME causes potentiation of cirazoline- and KCl-induced vasoconstriction respectively by inhibiting endothelial and neuronal NO synthase(s). Furthermore, our data indicate that NO synthase activity is not impaired in the mesenteric arterial bed of spontaneously hypertensive rats.

Adrenergic alpha-Agonists↗
PubMed1978

Stretch receptor control of renin release in perfused rat kidney: effect of high perfusate potassium.

1. These studies were conducted in the isolated perfused rat kidney to determine the effect of high perfusate K on the renin release induced by low perfusion pressure, renal vasoconstriction and isoprenaline, and to determine whether the magnitude of the K-induced inhibition equalled that observed with renal vasodilation and high perfusion pressure. 2. Raising perfusate K concentration from 4.2 to 56 mM suppressed basal renin release, and the 56 mM-K inhibited the renin release induced by low perfusion pressure (50 mmHg) or phenylephrine (0.83 micrometers). 3. Isoprenaline (0.79 micrometers) induced a marked increase in renin release; but high perfusate K, propranolol (0.28 mM), papaverine (0.39 mM), or high perfusion pressure (150 mmHg) inhibited this effect. 4. It is concluded that high perfusate K has a powerful inhibitory effect on the renin release induced by renal hypotension, vasoconstriction, and isoprenaline infusion, and that this effect may be mimicked by high perfusion pressure or renal vasodilation. A mechanism is proposed whereby these signals may inhibit renin release by depolarizing the juxtaglomerular granular cells.

Animals↗
PubMed2002

Hepatic haemodynamics: interrelationships between contrast enhancement and perfusion on CT and Doppler perfusion indices.

This study compares three techniques that evaluate hepatic haemodynamics for the detection of metastatic liver disease to determine the interrelationships between the techniques and to assess their equivalence. The three techniques studied were dedicated CT measurements of hepatic enhancement, CT measurements of perfusion and Doppler perfusion indices. 53 patients with proven malignancies of either breast or colon underwent a single location dynamic CT for measurement of hepatic perfusion and enhancement, whilst a subset of 12 patients underwent both CT perfusion and Doppler perfusion studies. Statistically significant correlations were found between CT arterial phase enhancement and CT arterial perfusion (r=0.612, p<0.001), and between both of these parameters and Doppler arterial flow (r=0.867, p<0.001 and r=0.842, p<0.001, respectively). Significant correlations were also found between both the ratio of CT arterial enhancement to peak enhancement and the CT arterial perfusion with the Doppler perfusion index (r=0.797, p=0.002 and r=0.725, p=0.008, respectively). Combined CT arterial and portal perfusion correlated with peak liver enhancement (r=0.614, p< 0.001), but Doppler measurements of portal flow did not correlate with any CT parameter. Increased arterial enhancement, perfusion or flow are valuable additional radiological signs for the presence of hepatic metastases that can be elicited by incorporating any one of these methods into existing imaging protocols.

Adult↗
PubMed1992

Ventilation-perfusion relationships in isolated blood-free perfused rabbit lungs.

The multiple inert gas elimination technique (MIGET) was applied to blood-free perfused isolated rabbit lungs. Commonly accepted criteria for reliability of the method were found to be fulfilled in this model. Ventilation-perfusion (VA/Q) distributions in isolated control lungs corresponded to those repeatedly detected under physiological conditions. In particular, a narrow unimodal dispersion of perfusate flow was observed: perfusion of low-VA/Q areas ranged below 1% and shunt flow approximately 2-3%; perfusion of high-VA/Q regions was not detected. Gas flow was characterized by narrow dispersion in the midrange-VA/Q areas. Application of a low level of PEEP (1 cmH2O) reduced shunt flow to less than 1%, and low-VA/Q areas were no longer noted. By using this PEEP-level, stable gas exchange conditions were maintained for greater than 5 h of extracorporeal perfusion. Graded embolization with small air bubbles caused a typical rightward shift (to higher VA/Q ratios) of mean ventilation, associated with the appearance of high-VA/Q regions and an increase in dead space ventilation. Mean perfusion was shifted leftward, and shunt flow was approximately doubled. Whole lung lavage with saline for washout of surfactant evoked a progressive manifold increase in shunt flow, accompanied by a moderate rise of perfusate flow to low-VA/Q areas. We conclude that the MIGET can be applied to isolated blood-free perfused rabbit lungs for assessment of gas exchange and that typical patterns of VA/Q mismatch are reproduced in this model.

Animals↗
PubMed1992

Effect of angiotensin II-induced changes in perfusion flow rate on chlorothiazide transport in the isolated perfused rat kidney.

Angiotensin II was used as a probe to study the effect of changes in perfusate flow rate on the renal clearance parameters of chlorothiazide in the isolated perfused rat kidney. Perfusion studies were performed in five rats with no angiotensin II present in the perfusate and in five rats with a 1-4 ng/min infusion of angiotensin II into the perfusate. Angiotensin II had a dramatic effect on the renal hemodynamics, resulting in a 43% decrease in perfusate flow, a 16% decrease in glomerular filtration rate (GFR), and a 45% increase in filtration fraction. Values for the fractional excretion of glucose were low and consistent, with or without angiotensin II. Although the unbound fraction (fu) of chlorothiazide was unchanged between treatments, the renal (CLr) and the secretion clearances were reduced by about 50% in the presence of angiotensin II; the excretion ratio [ER = CLr/(fu.GFR)] was reduced by 38% with angiotensin II present in the perfusate. Analysis of the data was complicated by the presence of a capacity-limited transport for renal tubular secretion. Transport parameters (+/- SD) were obtained and the corrected intrinsic secretory clearance [(Vmax/GFR)/Km] of chlorothiazide was 123 +/- 18 without angiotensin II vs. 72.8 +/- 30.0 with angiotensin II. These results demonstrate that alterations in organ perfusion can significantly reduce the clearance parameters of chlorothiazide in the rat IPK. These flow-induced changes in intrinsic secretory transport may reflect perturbations other than that of perfusion flow rate alone.

Angiotensin II↗
PubMed1992

An improved technique for isolated perfusion of rat livers and an evaluation of perfusates.

We have modified the apparatus for isolated rat liver perfusion (IPRL) in order to be able to perform two perfusions simultaneously. In addition, we studied the quality and stability of livers by comparison of five different perfusates: Blood (Group A), Original Krebs Henseleit buffer (Group B), Krebs buffer with glucose (Group C) or bovine serum albumin (BSA) added, (Group D). In a last group (E) albumin, glucose, and taurocholic acid were added to Krebs. After 180 min of perfusion, livers perfused with solutions including 2% albumin (Group D, E) had a significantly higher release of hepatocellular and endothelial cell (purine nucleoside phosphorylase) enzymes and lower bile production as compared to Groups A, B, and C (P less than 0.0001). Increasing levels of purine nucleoside phosphorylase (PNP), a reflection of damage to the microvascular endothelium preceded the increases in hepatocellular enzymes. Histologically, damages of sinusoidal endothelial cells and hepatocytes are appreciated moderate to severe in Groups D and E, slight to mild in Groups A and B, and not significant in Group C. These results suggest that BSA may have toxic effects to the perfused rat liver. These data also confirm that the IPRL modified for simultaneous perfusion of two livers is efficient, and that with this technique the rat liver can be optimally perfused for up to 3 hr with oxygenated Krebs Henseleit buffer without additives (Group B) and without blood. These two improvements should allow those performing studies with perfused rat livers to obtain data in a more efficient, accurate, and inexpensive fashion.

Animals↗
PubMed1983

Hypothermic perfusion of human kidney carcinoma: effects on viability and perfusate distribution.

A more deteriorating effect on tumour tissue than on normal renal parenchyma by hypothermic perfusion has previously been observed. The purpose of this study was to further evaluate changes in the perfusate distribution and the viability of normal cortical tissue and of kidney carcinoma during hypothermic perfusion. Tumour-involved kidneys obtained by nephrectomy from 12 patients were studied either with regard to viability, as measured with the Na+-K+ pump function in incubated tissue slices, or with regard to perfusate flow, as analysed with an isotope labelled microsphere technique. Six days of hypothermic perfusion decreased the potassium content in the tumour tissue, while it was mainly unchanged in the cortical tissue. The steady-state level of potassium in incubated slices reflected that the transmembrane K+ influx was unchanged after 6 days of perfusion in normal cortical tissue, whereas a significant reduction was observed in the tumour tissue. The relative perfusate flow in the tumour, when compared to the normal kidney cortex flow, was reduced from 60% after 1 hr of perfusion to 30% after 6 days of perfusion.

Adult↗
PubMed1987

Effects of ischemia and perfusion temperature on the synthesis of stress-induced (heat shock) proteins in isolated and perfused rat hearts.

Isolated and perfused rat hearts were examined by 2-dimensional gel electrophoresis and liquid scintillation counting to determine the effect of ischemia or perfusion temperature on protein synthesis. Isolated hearts were subjected to ischemia at either 4 degrees, 20 degrees, or 30 degrees C and then perfused at 37 degrees C and radio-labeled with [3H]-leucine from 0.5 to 2.5 h of perfusion. Following 0.5 h of 4 degrees C or 0.2 h of 20 degrees C ischemia, minimal or no effect was seen by fluorography on the patterns of protein synthesis and there was no apparent synthesis of the stress-induced (heat shock) protein with Mr = 71,000 (SP71). After 4.0 h of 4 degrees C or 0.5 h of 20 degrees C ischemia, SP71 was detectable on fluorograms. After 17 h of 4 degrees C or 1 h of 20 degrees C or 30 degrees C ischemia, SP71 was a prominent spot on fluorograms; the percentage incorporation of precursor into SP71 was significantly increased and overall incorporation of precursor into protein appeared depressed. Following 17 h at 4 degrees C, during which time the buffer was continuously oxygenated, percentage incorporation of precursor into SP71 was only moderately increased, suggesting that hypoxia was responsible for the high level of SP71 synthesis. The effect of perfusion temperature was initially examined using a perfusion method which results in a moderate synthesis of SP71 at 37 degrees C between 2.5 and 4.5 h of perfusion. Fluorograms revealed synthesis of some normal proteins at all temperatures, with little or no synthesis of SP71 at 31 degrees and 34 degrees C, moderate synthesis at 37 degrees C, and intense synthesis at 40 degrees C. The percentage incorporation of precursor into SP71 and total incorporation of precursor appeared depressed at 31 degrees C and 34 degrees C, from that at 37 degrees C, while at 40 degrees C, percentage incorporation of precursor into SP71 was significantly increased but overall incorporation of precursor into protein appeared depressed. When SP71 synthesis was induced by 17 h of 4 degrees C ischemia, hearts were sensitive to a lower perfusion temperature (34 degrees C); the percent incorporation of precursor into SP71 was significantly reduced from that seen at 37 degrees C. Interestingly, the effect of prolonged ischemia on protein synthesis (increased synthesis of SP71; suppression of overall synthesis) is the same as the heat shock response seen after perfusion at 40 degrees C.

Animals↗
PubMed1997

The effects of perfusion conditions on melphalan distribution in the isolated perfused rat hindlimb bearing a human melanoma xenograft.

An isolated rat hindlimb perfusion model carrying xenografts of the human melanoma cell line MM96 was used to study the effects of perfusion conditions on melphalan distribution. Krebs-Henseleit buffer and Hartmann's solution containing 4.7% bovine serum albumin (BSA) or 2.8% dextran 40 were used as perfusates. Melphalan concentrations in perfusate, tumour nodules and normal tissues were measured using high-performance liquid chromatography (HPLC). Increasing the perfusion flow rates (from 4 to 8 ml min(-1)) resulted in higher tissue blood flow (determined with 51Cr-labelled microspheres) and melphalan uptake by tumour and normal tissues. The distribution of melphalan within tumour nodules and normal tissues was similar for both Krebs-Henseleit buffer and Hartmann's solution; however, tissue concentrations of melphalan were significantly higher for a perfusate containing 2.8% dextran 40 than for one containing 4.7% BSA. The melphalan concentration in the tumour was one-third of that found in the skin if the perfusate contained 4.7% BSA. In conclusion, this study has shown that a high perfusion flow enhances the delivery of melphalan into implanted tumour nodules and normal tissues, and a perfusate with low melphalan binding (no albumin) is preferred for maximum uptake of drug by the tumour.

Animals↗
PubMed2002

Nifedipine improves blood flow and oxygen supply, but not steady-state oxygenation of tumours in perfusion pressure-controlled isolated limb perfusion.

Isolated limb perfusion allows the direct application of therapeutic agents to a tumour-bearing extremity. The present study investigated whether the dihydropyridine-type Ca(2+)-channel blocker nifedipine could improve blood flow and oxygenation status of experimental tumours during isolated limb perfusion. Perfusion was performed by cannulation of the femoral artery and vein in rats bearing DS-sarcoma on the hind foot dorsum. Perfusion rate was adjusted to maintain a perfusion pressure of 100-140 mmHg throughout the experiment. Following equilibration, nifedipine was continuously infused for 30 min (8.3 microg min(-1) kg(-1) BW). During constant-pressure isolated limb perfusion, nifedipine can significantly increase perfusion rate (+100%) and RBC flux (+60%) through experimental leg tumours. "Steal phenomena" in favour of the surrounding normal tissue and oedema formation were not observed. Despite the increased oxygen availability (+63%) seen upon application of this calcium channel blocker, nifedipine does not result in a substantial reduction of tumour hypoxia, most probably due to an increase in O(2) uptake with rising O(2) supply to the tumour-bearing hind limb. Nifedipine application during isolated limb perfusion can enhance tumour microcirculation and may therefore promote the delivery (pharmacokinetics) of anti-cancer drugs to the tumour and by this improve the efficacy of pressure-controlled isolated limb perfusion.

Animals↗
PubMed2003

Effects of different perfusates on functional parameters of isolated perfused dog kidneys.

BACKGROUND: The isolated perfused canine kidney has been established as a valid model for conducting both renal physiology and transplantation research. This model is of particular importance for developing new strategies to improve graft function after renal transplantation. In the present study, a newly developed method using isolated haemoperfused porcine kidneys was adapted for use in canine kidneys. In contrast to haemoperfusion, synthetic perfusion media can be standardized and can prevent the initiation of blood-mediated reperfusion reactions. Thus, an additional aim was to determine whether blood could be replaced by synthetic cell-free perfusion solutions. METHODS: Canine kidneys (n = 30) were harvested from donors euthanized in veterinary practices for causes unrelated to the present study. The kidneys were isolated and perfused with autologous blood or cell-free synthetic electrolyte buffer (Tyrode solution). During perfusion, we monitored renal perfusate flow (RPF), glomerular filtration rate (GFR), electrolyte and glucose reabsorption, oxygen consumption and urine concentration. RESULTS: Changes in perfusion medium did not affect the RPF. In contrast, GFR, urine concentration and oxygen consumption were significantly higher, whereas fractional excretion of sodium and glucose were significantly lower in blood- than in Tyrode-perfused kidneys. CONCLUSIONS: This system offers a simple model for studying whole-organ functional alterations after acute renal ischaemia. Renal function indicators were below values reported during in vivo physiological conditions. These functions were better conserved when kidneys were perfused with autologous blood than with Tyrode.

Animals↗
PubMed1998

Impact of immunoadsorption on complement activation, immunopathology, and hepatic perfusion during xenogeneic pig liver perfusion.

BACKGROUND: The impact of antibody adsorption by immunoapheresis on liver damage, complement activation, and hepatic perfusion was evaluated against the background of an application in extracorporeal pig liver perfusion for hepatic coma. METHODS: Eighteen pig livers were ex vivo perfused close to physiological conditions with fresh human blood for 4 hr. The influence of the perfusion circuit was investigated by perfusions of the circuit in the absence of livers (group 1 [G1]; n=5). Livers were xenoperfused without modifications in group 2 (G2; n=6). In group 3 (G3; n=6), pure Sepharose columns were used prior to liver perfusion. Immunoapheresis with Ig-Therasorb 100 columns was used in group 4 (G4; n=6). RESULTS: IgG was reduced by 95%, IgM by 72%, and IgA by 82% in G4, but only by about 30% in G3 (P<0.05). C4d, Bb fragment, and C3a levels were significantly lower in G4 than in G3 and G2 (P<0.05) after 180 min. Immunoadsorption diminished antibody and complement deposition as well as hepatocellular damage in G4. Portal angiographies demonstrated improved hepatic perfusion in G4. CONCLUSION: Immunoapheresis reduced organ damage as well as complement activation and improved hepatic perfusion during xenogeneic pig liver perfusion.

Acute Disease↗
PubMed2006

Assessment of differential pulmonary blood flow using perfusion magnetic resonance imaging: comparison with radionuclide perfusion scintigraphy.

OBJECTIVES: We sought to assess the agreement between lung perfusion ratios calculated from pulmonary perfusion magnetic resonance imaging (MRI) and those calculated from radionuclide (RN) perfusion scintigraphy. MATERIALS AND METHODS: A retrospective analysis of MR and RN perfusion scans was conducted in 23 patients (mean age, 60 +/- 14 years) with different lung diseases (lung cancer = 15, chronic obstructive pulmonary disease = 4, cystic fibrosis = 2, and mesothelioma = 2). Pulmonary perfusion was assessed by a time-resolved contrast-enhanced 3D gradient-echo pulse sequence using parallel imaging and view sharing (TR = 1.9 milliseconds; TE = 0.8 milliseconds; parallel imaging acceleration factor = 2; partition thickness = 4 mm; matrix = 256 x 96; in-plane spatial resolution = 1.87 x 3.75 mm; scan time for each 3D dataset = 1.5 seconds), using gadolinium-based contrast agents (injection flow rate = 5 mL/s, dose = 0.1 mmol/kg of body weight). The peak concentration (PC) of the contrast agent bolus, the pulmonary blood flow (PBF), and blood volume (PBV) were computed from the signal-time curves of the lung. Left-to-right ratios of pulmonary perfusion were calculated from the MR parameters and RN counts. The agreement between these ratios was assessed for side prevalence (sign test) and quantitatively (Deming-regression). RESULTS: MR and RN ratios agreed on side prevalence in 21 patients (91%) with PC, in 20 (87%) with PBF, and in 17 (74%) with PBV. The MR estimations of left-to-right perfusion ratios correlated significantly with those of RN perfusion scans (P < 0.01). The correlation was higher using PC (r = 0.67) and PBF (r = 0.66) than using PBV (r = 0.50). The MR ratios computed from PBF showed the highest accuracy, followed by those from PC and PBV. Independently from the MR parameter used, in some patients the quantitative difference between the MR and RN ratios was not negligible. CONCLUSIONS: Pulmonary perfusion MRI can be used to assess the differential blood flow of the lung. Further studies in a larger group of patients are required to fully confirm the clinical suitability of this imaging method.

Contrast Media↗
PubMed2002

Normothermic blood perfusion of isolated rabbit kidneys. III. In vitro physiology of kidneys after perfusion with Euro-Collins solution or 7.5 M cryoprotectant (VS4).

Cryopreservation of solid organs might be possible using a mixture of cell-permeable agents, cryoprotectants (CPA), which are designed to completely preclude ice crystal formation during cooling to cryogenic temperatures. The effects of a specific prototype solution (VS4) were evaluated by normothermic blood perfusion in vitro. Rabbit kidneys were divided into three groups: untreated controls ( n=7), Euro-Collins (EC)-perfused controls ( n=6) and VS4 (49%, w/v) CPA-perfused kidneys ( n=7). After a 2-h blood perfusion, five of the seven CPA-perfused kidneys developed polyuria (0.21 mlxmin(-1)xg(-1)) relative to untreated controls (0.07 mlxmin(-1)xg(-1)) or EC-perfused kidneys (0.06 mlxmin(-1)xg(-1)), owing to the lower reabsorption of water (34.3%), Na(+) (34.2%) and glucose (35.6%). Furthermore, two kidneys were non-functional with virtually no urine production. Reduced tubular function was associated with reduced oxygen consumption (3.6 versus 2.3 versus 2.0 micromolexmin(-1)xg(-1) for controls, EC- and CPA-perfused kidneys, respectively) and increased weight gain (17% versus 20% versus 30%, respectively) after blood perfusion. Therefore, the current results provide insight into both the physiological effects of VS4 and the limits of reversibility of renal pathophysiological states. Our results also indicate that in vitro monitoring of oxygen consumption and weight gain of perfused organs could be used as predictors of renal function.

Animals↗