Evaluation of competence in ultrasound-guided procedures-a generic assessment tool developed through the Delphi method.

OBJECTIVES: To develop a generic and objective tool for assessing competence in percutaneous ultrasound-guided procedures. METHODS: Interventional ultrasound experts from the Nordic countries were invited to participate in a three-round Delphi process. A steering committee was formed to manage the process. In round 1, the experts were asked to suggest all aspects to consider when assessing competence in US-guided procedures. Suggestions were analyzed and condensed into assessment items. In round 2, the expert panel rated these items on a 1-5 scale and suggested new items. Items with a mean rating of ≤ 3.5 were excluded. In round 3, the expert panel rated the list items and suggested changes to the items. RESULTS: Twenty-five experts were invited, and response rates in the three rounds were 68% (17 out of 25), 100% (17 out of 17), and 100% (17 out of 17). The three-round Delphi process resulted in a 12-item assessment tool, using a five-point rating scale. The final assessment tool evaluates pre-procedural planning, US technique, procedural technique, patient safety, communication, and teamwork. CONCLUSIONS: Expert consensus was achieved on a generic tool for assessment of competence in percutaneous ultrasound-guided procedures-the Interventional Ultrasound Skills Evaluation (IUSE). This is the initial step in ensuring a valid and reliable method for assessment of interventional US skill. KEY POINTS: • Through a Delphi process, expert consensus was achieved on the content of an assessment tool for percutaneous ultrasound-guided procedures-the Interventional Ultrasound Skills Evaluation (IUSE) tool. • The IUSE tool is comprehensive and covers pre-procedural planning, US technique, procedural technique, patient safety, communication, and teamwork. • This is an important step in ensuring valid and reliable assessment of interventional US skills.

Effects of marine n-3 fatty acid supplementation in renal transplantation: A randomized controlled trial.

Marine n-3 fatty acids (FAs) may exert beneficial effects on inflammation, fibrosis, and endothelial function, which could preserve renal graft function. In this randomized controlled trial, 132 Norwegian renal transplant recipients received either 2.6 g of marine n-3 FAs or olive oil (control) daily for 44 weeks, in addition to standard care. Thirty patients did not complete the trial. The primary endpoint was change (Δ) in measured glomerular filtration rate (mGFR) during follow-up. We found no significant difference in Δ mGFR between the marine n-3 FA group and controls (6.7 vs 3.8 mL/min per 1.73 m2 , P = .15). Significant beneficial effects from marine n-3 FA supplementation were, however, seen in secondary endpoints plasma triglycerides, plasma high-sensitivity C-reactive protein, and brachial artery flow-mediated dilation. In the per-protocol population, the renal graft indices percent interstitial fibrosis and Chronic Allograft Damage Index also were significantly lower in the marine n-3 FA group. The cumulative incidence of adverse events did not differ between the marine n-3 FA group (n = 218) and controls (n = 240). In conclusion, marine FA supplementation did not improve renal function compared with controls, but was safe, lowered plasma triglyceride and high-sensitivity C-reactive protein levels, and improved endothelial function (Clinical.Trials.gov identifier NCT01744067).

Enhanced liver fibrosis score predicts transplant-free survival in primary sclerosing cholangitis.

UNLABELLED: There is a need to determine biomarkers reflecting disease activity and prognosis in primary sclerosing cholangitis (PSC). We evaluated the prognostic utility of the enhanced liver fibrosis (ELF) score in Norwegian PSC patients. Serum samples were available from 305 well-characterized large-duct PSC patients, 96 ulcerative colitis patients, and 100 healthy controls. The PSC patients constituted a derivation panel (recruited 1992-2006 [n = 167]; median age 41 years, 74% male) and a validation panel (recruited 2008-2012 [n = 138]; median age 40 years, 78% male). We used commercial kits to analyze serum levels of hyaluronic acid, tissue inhibitor of metalloproteinases-1, and propeptide of type III procollagen and calculated ELF scores by the previously published algorithm. Results were also validated by analysis of ELF tests using the ADVIA Centaur XP system and its commercially available reagents. We found that PSC patients stratified by ELF score tertiles exhibited significantly different transplant-free survival in both panels (P < 0.001), with higher scores associated with shorter survival, which was confirmed in the validation panel stratified by ELF test tertiles (P = 0.003). The ELF test distinguished between mild and severe disease defined by clinical outcome (transplantation or death) with an area under the curve of 0.81 (95% confidence interval [CI] 0.73-0.87) and optimal cutoff of 10.6 (sensitivity 70.2%, specificity 79.1%). In multivariate Cox regression analysis in both panels, ELF score (hazard ratio = 1.9, 95% CI 1.4-2.5, and 1.5, 95% CI 1.1-2.1, respectively) was associated with transplant-free survival independently of the Mayo risk score (hazard ratio = 1.3, 95% CI 1.1-1.6, and 1.6, 95% CI 1.2-2.1, respectively). The ELF test correlated with ultrasound elastography in separate assessments. CONCLUSION: The ELF score is a potent prognostic marker in PSC, independent of the Mayo risk score.

In patients with type 1 diabetes simultaneous pancreas and kidney transplantation preserves long-term kidney graft ultrastructure and function better than transplantation of kidney alone.

AIMS/HYPOTHESIS: In patients with type 1 diabetes and end-stage renal disease (ESRD) we aimed to determine whether long-term normoglycaemia, as achieved by successful simultaneous pancreas and kidney (SPK) transplantation, would preserve kidney graft structure and function better than live donor kidney (LDK) transplantation alone. METHODS: Estimated GFR (eGFR) was calculated in SPK (n = 25) and LDK (n = 17) recipients in a stable phase 3 months after transplantation and annually during follow-up. Kidney graft biopsies were obtained at follow-up for measurement of glomerular volume (light microscopy), glomerular basement membrane (GBM) and podocyte foot process widths and mesangial volume fraction (electron microscopy). RESULTS: SPK and LDK recipients were similar in age and diabetes duration at engraftment. Donor age was higher in the LDK group. Median follow-up time was 10.1 years. Mean HbA1c levels during follow-up were 5.5 ± 0.4% (37 ± 5 mmol/mol) and 8.3 ± 1.5% (68 ± 16 mmol/mol) in the SPK and LDK group, respectively (p < 0.001). Compared with SPK recipients, LDK recipients had wider GBM (369 ± 109 nm vs 281 ± 57 nm; p = 0.008) and increased mesangial volume fraction (median 0.23 [range 0.13-0.59] vs 0.16 [0.10-0.41]; p = 0.007) at follow-up. Absolute eGFR change from baseline was -11 ± 21 and -23 ± 15 ml min(-1) 1.73 m(-2) (p = 0.060), whereas eGFR slope was -1.1 (95% CI -1.7, -0.5) and -2.6 (95% CI -3.1, -2.1) ml min(-1) 1.73 m(-2) per year in the SPK and LDK group, respectively (p = 0.001). CONCLUSIONS/INTERPRETATION: In patients with type 1 diabetes and long-term normoglycaemia after successful SPK transplantation, kidney graft ultrastructure and function were better preserved compared with LDK transplantation alone.

Color Doppler ultrasound-guided transducer compression of post biopsy bleeding of kidney transplants.

BACKGROUND: Color Doppler ultrasound (CDUS) has a potential of early detection of post biopsy bleeding. We describe CDUS guidance in planning, acquisition, and, in the case of bleeding, compression of the needle tract in biopsy procedures of kidney transplants. METHODS: Eighty-three kidney transplant biopsy procedures performed on clinical indication were performed in 71 adult patients, 25 women, mean age 51 years, using CDUS and 18-G biopsy needles. Bleeding needle tracts were compressed using CDUS guidance. RESULTS: CDUS immediately detected blood leakage and facilitated compression of the bleeding needle tract in 34 (41%) of the 83 procedures, including 53 (25%) of 215 needle passes. In 34 bleeding procedures, the mean duration of the longest bleeding time after a needle pass was 124 seconds (median, 20 seconds; range, 3-1440 seconds). In 12 of these procedures (35%), the bleeding time was 30 seconds or more. In six procedures (18%), a bleeding of 120 seconds or more was observed. Complications included seven small hematomas. Five hematomas developed in procedures where the longest duration CD bleeding was 120 seconds or more. CONCLUSIONS: CDUS detects bleeding and facilitates direct transducer compression of the needle tract in a substantial portion of biopsy procedures of kidney transplants. Only minor hematomas occurred.

Tissue elasticity estimated by acoustic radiation force impulse quantification depends on the applied transducer force: an experimental study in kidney transplant patients.

OBJECTIVES: Acoustic radiation force impulse (ARFI) quantification estimates tissue elasticity by measuring shear-wave velocity (SWV) and has been applied to various organs. We evaluated the impact of variations in the transducer force applied to the skin on the SWV ultrasound measurements in kidney transplant cortex and ARFI's ability to detect fibrosis in kidney transplants. METHODS: SWV measurements were performed in the cortex of 31 patients with kidney allografts referred for surveillance biopsies. A mechanical device held the transducer and applied forces were equal to a compression weight of 22, 275, 490, 975, 2,040 and 2,990 g. RESULTS: SWV group means were significantly different by repeat measures ANOVA [F(2.85,85.91) = 84.75, P < 0.0005 for 22, 275, 490, 975 and 2,040 g compression weight] and also by pairwise comparisons. Biopsy specimens were sufficient for histological evaluation in 29 of 31 patients. Twelve had grade 0, 11 grade 1, five grade 2 and one grade 3 fibrosis. One-way ANOVA showed no difference in SWV performed with any of the applied transducer forces between grafts with various degrees of fibrosis. CONCLUSION: SWV measurements in kidney transplants are dependent on the applied transducer force and do not differ in grafts with different grades of fibrosis. KEY POINTS: • Acoustic radiation force impulses (ARFI) can quantify tissue elasticity during ultrasound examinations. • Elasticity estimated by ARFI in kidney transplants depends on applied transducer force. • ARFI quantification cannot detect renal allograft fibrosis. • ARFI elasticity estimates may in general vary with applied transducer force.

Renal Cell Carcinoma and Kidney Transplantation: A Narrative Review.

Kidney transplant recipients (KTRs) are at increased risk of developing renal cell carcinoma (RCC). The cancer can be encountered at different steps in the transplant process. RCC found during work-up of a transplant candidate needs treatment and to limit the risk of recurrence usually a mandatory observation period before transplantation is recommended. An observation period may be omitted for candidates with incidentally discovered and excised small RCCs (<3 cm). Likewise, RCC in the donor organ may not always preclude usage if tumor is small (<2 to 4 cm) and removed with clear margins before transplantation. After transplantation, 90% of RCCs are detected in the native kidneys, particularly if acquired cystic kidney disease has developed during prolonged dialysis. Screening for RCC after transplantation has not been found cost-effective. Treatment of RCC in KTRs poses challenges with adjustments of immunosuppression and oncologic treatments. For localized RCC, excision or nephrectomy is often curative. For metastatic RCC, recent landmark trials in the nontransplanted population demonstrate that immunotherapy combinations improve survival. Dedicated trials in KTRs are lacking. Case series on immune checkpoint inhibitors in solid organ recipients with a range of cancer types indicate partial or complete tumor response in approximately one-third of the patients at the cost of rejection developing in ~40%.

Contrast enhanced ultrasound in the detection of liver metastases: a prospective multi-centre dose testing study using a perfluorobutane microbubble contrast agent (NC100100).

OBJECTIVE: To conduct a dose testing analysis of perfluorobutane microbubble (NC100100) contrast-enhanced ultrasound (CEUS) to determine the optimal dose for detection of liver metastases in patients with extra-hepatic primary malignancy. METHODS: 157 patients were investigated with conventional US and CEUS. CEUS was performed following intravenous administration of perfluorobutane microbubbles (using one dose of either 0.008, 0.08, 0.12 or 0.36 µL/kg body weight). Three blinded off-site readers recorded the number and locations of metastatic lesions detected by US and CEUS. Contrast enhanced CT and MRI were used as the "Standard Of Reference" (SOR). Sensitivity, specificity and accuracy of liver metastasis detection with US versus CEUS, for each dose group were obtained. Dose group analysis was performed using the Chi-square test. RESULTS: 165 metastases were present in 92 patients who each had 1-7 lesions present on the SOR. Sensitivity of US versus CEUS (for all doses combined) was 38% and 67% (p = 0.0001). The 0.12 dose group with CEUS (78%) had significantly higher sensitivity and accuracy (70%) compared to other dose groups (p < 0.05). CONCLUSION: The diagnostic performance of CEUS is dose dependent with the 0.12 µL/kg NC100100 dose group showing the greatest sensitivity and accuracy in detection of liver metastases.

Spontaneous regression of initially elevated peak systolic velocity in renal transplant artery.

There is limited knowledge about the incidence, clinical implication and spontaneous course of transplant renal artery stenosis detected early after renal transplantation. We performed Doppler ultrasound examination of the transplant artery(s) 2 months after transplantation in 98 consecutive patients and peak systolic velocity (PSV) was measured. All patients with an elevated PSV ≥1.8 m/s were reexamined 20 months later and clinical data were followed for 3 years. At the initial examination 2 months after transplantation 15 recipients had a PSV ≥1.8 m/s, mean value for PSV 2.5 (1.8-3.6) m/s, whereas 83 recipients had a normal PSV of 1.3 (0.7-1.7) m/s (P<0.01). At baseline there were no statistical significant differences in clinical parameters between the high PSV versus normal PSV recipients. Twenty (15-28) months after transplantation 14 patients with initial elevated PSV were re-examined. There was an overall mean reduction in PSV of 0.5 (-0.7 to 1.2) m/s from 2.4 (1.8-3.4) m/s to 1.9 (1.2-3.1) m/s (P=0.02). Detection of a high PSV early after transplantation did not affect graft function or blood pressure 3 years after engraftment. We conclude that a high PSV, at 2 months after engraftment, seems to be more of an 'incidental finding' that should be re-challenged and carefully interpreted.

Assessment of renal allograft fibrosis by acoustic radiation force impulse quantification--a pilot study.

Chronic allograft nephropathy characterized by interstitial fibrosis and tubular atrophy is a major cause of renal transplant failure. Acoustic radiation force impulse (ARFI) quantification is a promising noninvasive method for assessing tissue stiffness. We evaluated if the method could reveal renal transplant fibrosis. In a prospective study, 30 adult renal transplant recipients were included. ARFI quantification, given as shear wave velocity (SWV), of the renal cortex was performed by two observers. SWV was compared to grade of fibrosis (0-3) in biopsies. The median SWV was 2.8 m/s (range: 1.6-3.6), 2.6 m/s (range: 1.8-3.5) and 2.5 m/s (range: 1.6-3) for grade 0 (n = 12), 1 (n = 10) and grades 2/3 (n = 8) fibrosis respectively. SWV did not differ significantly in transplants without and with fibrosis (grade 0 vs. grade 1, P = 0.53 and grade 0 vs. grades 2/3, P = 0.11). The mean intraobserver coefficient of variation was 22% for observer 1 and 24% for observer 2. Interobserver agreement, expressed as intraclass correlation coefficient was 0.31 (95% CI: -0.03 to 0.60). This study does not support the use of ARFI quantification to assess low-grade fibrosis in renal transplants. ARFI quantification in its present stage of development has also high intra- and interobserver variation in renal transplants.

Non-invasive assessment of renal allograft fibrosis by dynamic sonographic tissue perfusion measurement.

BACKGROUND: Chronic allograft nephropathy (CAN) characterized by interstitial fibrosis and tubular atrophy is a major cause of renal transplant failure. The diagnosis can currently only be verified by a graft biopsy. PURPOSE: To evaluate whether non-invasive dynamic color Doppler sonographic parenchymal perfusion measurements are different in grafts with various degrees of biopsy proven renal transplant fibrosis. MATERIAL AND METHODS: Forty-nine adult patients were prospectively included. Four patients were excluded. Color Doppler videos from the renal cortex were recorded. Perfusion in the renal cortex was evaluated using a software package which calculates color pixel area and flow velocity, encoded by each pixel inside a region of interest of a video sequence. The software calculates parameters that describe tissue perfusion numerically. Two of these, the perfusion intensity and tissue pulsatility index, were compared to grade of interstitial fibrosis (0-3) in biopsies. Observer agreement was evaluated in a subset of 12 patients. RESULTS: Of the 45 patients analyzed, 18 patients had grade 0, 18 had grade 1, seven had grade 2 and two had grade 3 fibrosis. The mean perfusion intensity of grade 0 was significantly higher than that of grade 2 and 3 fibrosis in the proximal cortical layer (1.65 m/s vs. 0.84 m/s, P = 0.008). No significant difference was found between grade 0 and grade 1 fibrosis. Perfusion intensity was correlated to estimated glomerular filtration rate (Pearson r 0.51, P = 0.001, R(2) = 0.26 and 0.46, P = 0.001, R(2) = 0.22 in the distal and proximal cortex, respectively). Inter-observer agreement of the perfusion intensity, expressed as intraclass correlation coefficient was 0.69 in the proximal part of the cortex. Intra-observer agreement was 0.85 for observer 1 and 0.82 for observer 2. CONCLUSION: Perfusion intensity assessed by dynamic color Doppler measurements is significantly reduced in allografts with grade 2 and 3 fibrosis compared to allografts without fibrosis. Further studies involving longitudinal assessment of allografts undergoing protocol biopsies would be of interest.

Early detection of complications in pancreas transplants by microdialysis catheters, an observational feasibility study.

BACKGROUND: Despite advances in immunosuppression and surgical technique, pancreas transplantation is encumbered with a high rate of complication and graft losses. Particularly, venous graft thrombi occur relatively frequently and are rarely detected before the transplant is irreversibly damaged. METHODS: To detect complications early, when the grafts are potentially salvageable, we placed microdialysis catheters anteriorly and posteriorly to the graft in a cohort of 34 consecutive patients. Glucose, lactate, pyruvate, and glycerol were measured at the bedside every 1-2 hours. RESULTS: Nine patients with graft venous thrombosis had significant lactate and lactate-to-pyruvate-ratio increases without concomitant rise in blood glucose or clinical symptoms. The median lactate in these patients was significantly higher in both catheters compared to non-events (n = 15). Out of the nine thrombi, four grafts underwent successful angiographic extraction, one did not require intervention and four grafts were irreversibly damaged and explanted. Four patients with enteric anastomosis leakages had significantly higher glycerol measurements compared to non-events. As with the venous thrombi, lactate and lactate-to-pyruvate ratio were also increased in six patients with graft surrounding hematomas. CONCLUSIONS: Bedside monitoring with microdialysis catheters is a promising surveillance modality of pancreatic grafts, but differentiating between the various pathologies proves challenging.

Clinical utility of microbubble contrast-enhanced ultrasound in the diagnosis of hepatic artery occlusion after liver transplantation.

To evaluate the frequency of use and the diagnostic accuracy of real-time contrast-enhanced ultrasound (CEUS) in the diagnosis of hepatic artery occlusion after liver transplantation. One hundred and fifty-two liver transplantations in 142 adult subjects, comprising 80 male patients and 62 female patients, were studied. After surgery, liver circulation was routinely assessed by conventional Doppler ultrasound (US). Wherever the examiners were not confident about the state of the circulation, CEUS was performed with one or more doses of a sulfur hexafluoride (SF-6)-containing second-generation contrast agent intravenously. Clinical follow up including repeat Doppler US, computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) of the liver vasculature were used as reference standards. During the first month after transplantation, Doppler US was inconclusive with regard to patency of the hepatic artery (HA) circulation in 20 (13 %) of 152 transplantations. CEUS was performed in these patients, and detected six cases of HA thrombosis (HAT) in five transplants. CEUS correctly ruled out HA occlusion in 15 transplants. All HA occlusions occurred during the first 14 days after transplantation. In the subset of transplantations examined with CEUS, the sensitivity, specificity and accuracy of CEUS were 100%. In approximately 13% of cases, conventional Doppler US did not provide sufficient visualization of the HA after liver transplantation. In these cases, correct diagnosis was achieved by supplementary CEUS.

Long-term clinical outcome of paediatric kidneys transplanted to adults.

BACKGROUND: We have earlier shown an increase in the size and excellent graft function of paediatric kidneys transplanted to adults up to 1 year following transplantation. This study was performed to assess the long-term outcome of these transplants. METHODS: From a primary cohort of 19 adults, receiving a first kidney transplant from a paediatric donor <10 years of age, 16 patients were available for a complete long-term follow-up, 5-9 years post-transplant. Of these, eight patients were transplanted with a donor of <5 years. All medical files and registry data of the cohort, from the time of transplantation to the follow-up time point, were recalled and events were registered. The patients' general condition, body weight, blood and urine tests, blood pressure (BP), use of antihypertensive agents and GFR were recorded. To explore the temporal increment in the size of paediatric donor kidneys transplanted to adults, the maximal cranio-caudal length of the kidneys from the time of transplantation to follow-up was established by ultrasound. Volumes (length x width x thickness x pi/6) of en bloc kidneys versus single paediatric kidneys and adult-to-adult transplants were compared. RESULTS: Long-term (7 years, median) patient and graft survival was 95% and 89%, respectively. Mean serum creatinine was 85 micromol/l (range, 32-131). The mean estimated GFR was 84 ml/min/1.73 m(2). The mean BP was 134/79 mmHg (range, 120-185/70-90). The number of antihypertensive agents used was not statistically different from the number used at 1 year post-transplant. None of the patients had significant proteinuria as a sign of hyperfiltration injury of the graft. There were no statistically significant increases in the maximal cranio-caudal length of the transplanted kidney(s) from 1 year post-transplant to follow-up; however, the en bloc kidneys tended to be larger than single paediatric grafts (240 ml and 204 ml) and adult-to-adult grafts (170 ml). CONCLUSION: Paediatric kidneys transplanted to adults should be considered as excellent for transplantation on a long-term basis.

Increased peak systolic velocity in the renal artery of paediatric kidneys transplanted to adult recipients.

BACKGROUND: Paediatric kidneys transplanted to adult recipients increase in size after transplantation. It is unknown if the renal artery diameter increases concomitantly with the kidney. This study was performed to assess if peak systolic velocity (PSV) in the renal arteries of paediatric kidneys transplanted to adult recipients is comparable to PSV in the renal arteries of adult kidneys transplanted to adult recipients. Subjects and methods. Fifteen adult patients with paediatric renal transplants were examined with ultrasound Doppler and compared with a control group of adult recipients with adult transplants. MR angiography (MRA) or intra-arterial angiography (IA) was performed in patients with elevated PSV. MRA renal diameters of the paediatric transplants were compared with adult transplants. RESULTS: The mean maximum PSV of the paediatric kidneys was 2.0 m/s (0.9-3.8), almost twice compared with the adult grafts transplanted to adult recipients, 1.1 m/s (0.7-1.6), P < 0.001. Seven paediatric transplants had a PSV >1.8 m/s, but only two had significant stenosis on MRA/IA. All patients had excellent blood pressure and renal function. The mean diameter of the paediatric renal arteries was 4.1 mm (3.4-6.0), whereas the mean for the adult renal arteries was 5.6 mm (4.8-6.9), P = 0.02. CONCLUSION: Adult recipients of paediatric kidneys have significantly higher maximum PSV in the renal artery compared to adult recipients of adult grafts. The significantly smaller renal artery diameter might explain the high PSV. A PSV >1.8 m/s by itself does not necessarily indicate transplant renal artery stenosis in paediatric kidneys transplanted to adult recipients, but should be related to clinical findings.

[Radiofrequency ablation of colorectal liver metastases]. / Radiofrekvensablasjon av kolorektale levermetastaser.

BACKGROUND: Radiofrequency (RF) ablation is a method that uses electrical current for thermal destruction of solid tumours. We present our experience with RF ablation in a patient population with non-resectable colorectal liver metastases. MATERIAL AND METHODS: 17 of the 23 patients with non-resectable liver metastases treated with RF ablation at Rikshospitalet University Hospital from 2003 to 2006, were included in a prospective non-randomized study with standardized follow-up. RESULTS: RF ablation was used to treat one liver metastasis in each patient, and was combined with liver resection in seven patients. The median follow-up time after RF ablation was 29 months (14-55). One-year survival was 100% and survival after both two and three years was 67%. Follow-up examinations revealed local tumour progression at the RF-treated site in eight patients, intrahepatic recurrences not related to the RF-treated site in eight patients and extrahepatic recurrence in nine patients. Four patients with intrahepatic recurrence were re-treated with a curative intent. DISCUSSION: Long-term survival is possible after RF ablation of selected patients with non-resectable colorectal liver metastases. Local tumour progression, intrahepatic- and extrahepatic tumour recurrence is common after RF ablation. Systematic follow-up can identify tumour recurrences that may be re-treated with a curative intent. Liver resection should still be considered the gold standard for patients with resectable colorectal liver metastases.

[CT colonography: a new method for detecting colorectal cancer and polyps]. / CT-kolografi for påvisning av kreft og polypper i tykktarm.

BACKGROUND: CT colonography is a new method for the detection of colorectal cancer and polyps. MATERIAL AND METHODS: The article is based upon a review of the literature in PubMed (1994-2005) for CT colonography, as well as the authors' own experience. RESULTS: The seven largest publications show 55-94% sensitivity and 92-98% specificity for polyps > or = 10 mm. Compared to conventional CT examinations, the method has different requirements for patient preparation and technique. Our own experience so far is limited, but promising. INTERPRETATION: CT colonography seems to be a good alternative to the barium enema examination and a suitable supplement to incomplete colonoscopy. Hands-on training of radiologists is required before optimal results can be obtained.

Contrast-enhanced ultrasound identifies reduced overall and regional renal perfusion during global hypoxia in piglets.

OBJECTIVE: It is well known from both clinical experience and animal research that renal hypoxia may lead to temporary or permanent renal failure, the severity being dependent largely on the duration and grade of the hypoxia. The medulla is more susceptible to hypoxic injury than the cortex because approximately 90% of the renal blood flow supplies the cortex. Various methods have been applied to evaluate renal perfusion in both experimental and clinical settings, including magnetic resonance imaging, computed tomography, laser Doppler, and contrast-enhanced ultrasound (CEUS). PURPOSE: The aim of this study was to evaluate changes in overall and regional renal perfusion with CEUS in response to global hypoxia. MATERIAL AND METHODS: Twelve newborn anesthetized piglets were exposed to general hypoxia with a fraction of inspired oxygen of 8% of 30 minutes duration. Resuscitation was performed with either 100% oxygen (n = 6) or air (21% oxygen) (n = 6) for 30 minutes followed by 7 hours of reoxygenation with air. Before, during, and after hypoxia, the left kidney was examined with CEUS using 0.2 mL IV of SonoVue followed by 2 mL saline flush. Five additional piglets served as controls. The kidney was examined using a 9-MHz linear transducer with low mechanical index (0.21) and pulse inversion contrast program. One region of interest was drawn in the renal cortex and 1 in the medulla to obtain the corresponding time intensity curves (TICs). From these curves, the peak intensity (PI), time to peak (TTP), upslope of the curve, area under the curve, and mean transit time (MTT) were recorded. Also, the renal arteriovenous transit time (AVTT) was registered. The resistance index (RI) was repeatedly measured in the renal artery. Contrast-enhanced ultrasound was repeated at regular intervals until the animals were sacrificed 8 hours after the hypoxic period. RESULTS: In the group of 12 piglets subjected to hypoxia, RI increased from 0.69 ± 0.08 at baseline to 0.99 ± 0.09 during hypoxia (P < 0.01), indicating severe general renal vasoconstriction. The AVTT increased from 2.6 ± 0.5 seconds at baseline to 6.7 ± 2.8 seconds during hypoxia (P < 0.001). The PI in the cortex decreased from a mean value of 38.6 ± 6.1 dB at baseline to 30.3 ± 9.7 dB during hypoxia (P < 0.05). In the medulla, only a minor, nonsignificant reduction in PI was observed during hypoxia. In the medulla, TTP and MTT increased from 6.4 ± 1.5 and 9.2 ± 1.7 seconds at baseline to 14.6 ± 8.4 seconds (P < 0.01) and 15.2 ± 5.6 seconds (P < 0.01), respectively, during hypoxia. In the cortex, no statistically significant changes in TTP or MTT were observed during hypoxia. A return to near-baseline values was observed for TTP, PI in both the medulla and cortex, as well as for RI and AVTT within 1 to 3 hours after hypoxia, and they remained relatively constant for the duration of the experiment.Less than 1 hour after the hypoxia, PI both in the cortex and the medulla was significantly higher in the group resuscitated with air than in the group resuscitated with 100% oxygen, 36.0 ± 4.3 versus 27.2 ± 2.2 dB (P < 0.05) and 33.3 ± 8.2 versus 21.1 ± 2.0 dB (P < 0.01), respectively. CONCLUSION: Global hypoxia induced changes in overall and regional renal perfusion detectable with CEUS. Cortical and medullary flows were affected differently by hypoxia; a strong increase in medullary TTP and MTT was observed, indicating a reduction in medullary blood flow velocity. In the cortex, a significant reduction in PI was found, probably because of a reduction in cortical blood volume. A faster recovery of both medullary and cortical PI in the group resuscitated with air could indicate that air might be more beneficial for renal perfusion than hyperoxia during resuscitation after renal hypoxia.