Doppler ultrasonographic evaluation of tissue revascularization following connective tissue graft at implant sites

AIM

To assess the Doppler ultrasonographic tissue perfusion at dental implant sites augmented with connective tissue graft (CTG) using coronally advanced flap (CAF) or tunnel technique (TUN).

MATERIALS AND METHODS

Twenty-eight patients presenting with isolated healthy peri-implant soft-tissue dehiscence (PSTD) were included in this randomized clinical trial. PSTDs were treated with either CAF + CTG or TUN + CTG. Ultrasound scans were taken at baseline, 1 week, 1 month, 6 months and 12 months. Tissue perfusion at the mid-facial, mesial and distal aspects of the implant sites was assessed by colour Doppler velocity (CDV) and power Doppler imaging (PDI). Early vascularization of the graft and the flap at 1 week and at 1 month were evaluated via dynamic tissue perfusion measurements (DTPMs), including flow intensity (FI), mean perfusion relief intensity (pRI) and mean perfused area (pA).

RESULTS

Regression analysis did not reveal significant differences in terms of mid-facial CDV and PDI changes between CAF and TUN over 12 months (p > .05), while significant differences between the two groups were observed at the interproximal areas (p < .001 for both CDV and PDI changes). Higher early DTPMs were observed at the TUN-treated sites in terms of mean FI of the graft (p = .027) and mean FI (p = .024) and pRI of the flap (p = .031) compared with CAF-treated sites at 1 week. Assessment of the FI direction showed that CTG perfusion at 1 week and at 1 month mainly occurred from the flap towards the implant/bone. Early tissue perfusion outcomes were found to be associated with the 12-month mean PSTD coverage and mucosal thickness gain.

CONCLUSIONS

Doppler ultrasonography shows tissue perfusion changes occurring at implant sites augmented with CTG. The main differences in tissue perfusion between CAF and TUN were observed at the interproximal sites, with early perfusion associated with clinical and volumetric outcomes at 12 months.

Ultrasound Doppler Flow Parameters Are Independently Associated with Renal Cortex Contrast-Enhanced Multidetector Computed Tomography Perfusion and Kidney Function

BACKGROUND

The assessment of kidney perfusion has an emerging significance in many diagnostic applications. However, whether and which of the ultrasound Doppler parameters better express renal cortical perfusion (RCP) was not shown. The study aimed to prove the usefulness of Doppler ultrasound parameters in the assessment of RCP regarding low-dose contrast-enhanced multidetector computer tomography (CE-MDCT) blood flow.

METHODS

Thirty non-stenotic kidneys in twenty-five hypertensive patients (age 58.9 ± 19.0) with mild-to-severe renal dysfunction were included in the study. Resistive index (RI) and end-diastolic velocity (EDV) in segmental arteries, color Doppler dynamic RCP intensity (dRCP), RI (dRI), pulsatility index (dPI), and CE-MDCT blood flow (CBF) in the renal cortex were estimated.

RESULTS

CBF correlated significantly with age, estimated glomerular filtration rate (eGFR), RI, EDV, dRI, dPI, and dRCP. In separate multivariable backward regression analyses, RI (R² = 0.290, p = 0.003) and dRCP (R² = 0.320, p = 0.001) were independently associated with CBF. However, in the common ultrasound model, only dRCP was independently related to CBF (R² = 0.317, p = 0.001). Only CBF and EDV were independently associated with eGFR (R² = 0.510, p < 0.001).

CONCLUSIONS

Renal cortical perfusion intensity is the best ultrasound marker expressing renal cortical perfusion. In patients with hypertension and kidney dysfunction, renal resistive index and end-diastolic velocity express renal cortical perfusion and kidney function, respectively.

Prognostic value of intraoperative measurements of renal tissue oxygenation and microcirculation on renal function in partial nephrectomy

BACKGROUND

Partial nephrectomy (PNx) can be associated with macrocirculatory and microcirculatory alterations, ultimately leading to acute kidney injury (AKI). Measuring kidney tissue oxygenation (μHbO2) and microcirculation during open PNx might be feasible to early detect these alterations and prevent postoperative AKI.

METHODS

μHbO2 and microcirculation were measured in 45 patients undergoing PNx by reflectance spectrophotometry and laser Doppler flowmetry (O2C™, Lea, Germany), related to ischemia time and tumour size. Pre- and postoperative creatinine levels were determined.

RESULTS

μHbO2 was lower after reperfusion than before clamping (72 vs. 75%), while microcirculation and regional haemoglobin did not differ. Ischemia time was 15.7 min on average. μHbO2 was higher without ischemia (80 vs. 70%, p = 0.109) and in T1a- than T1b-tumours, independent of ischemia time and reperfusion. The renal collecting system (RCS) was opened in 19/45 patients with μHbO2 of 68% after reperfusion compared to 74% with intact RCS. Postoperative complications occurred in 6/45 patients (13%). μHbO2 was 68% before clamping vs. 75% without complications. Serum creatinine of patients with T1b was higher compared to T1a (103 vs. 87 µmol/L). Patients with larger tumours had higher postoperative creatinine levels (173 vs. 124 µmol/L; p = 0.052).

CONCLUSION

We showed for the first time that the method is feasible to monitor renal tissue oxygenation at the level of microcirculation non-invasively and reproducibly during PNx. Tumour size seems to have a decisive influence on oxygenation and postoperative renal function. Our results imply that postoperative complications may be predicted by low intraoperative renal oxygenation and microcirculatory flow measurements.

Limited Accuracy of Colour Doppler Ultrasound Dynamic Tissue Perfusion Measurement in Diabetic Adults

Dynamic tissue perfusion measurement (DTPM) is a pre-described and available method in pediatric ultrasound to quantify tissue perfusion in renal Doppler ultrasound by particular video analysis software. This study evaluates DTPM during single and between repeated visits after 6 months, calibrates repeated DTPM within different region of interest (ROI) and compares DTPM with kidney function markers in adult patients with early diabetic nephropathy (n = 17). During repeated measurements, no association of readings at the same patients in the same (n = 3 readings) as well as repeated visit (n = 2 visits) could be retrieved. No association between DTPM, MDRD-GFR, albuminuria, age and duration of diabetes was observed. These negative results are presumably related to inconsistency of DTPM due to non-fixed ROI position as could be shown in calibrating series. Further development of the method should be performed to enable reproducible DTPM readings in adults.

Umbilical vein vasomotion detected in vivo by serial three-dimensional pixelwise spatially angle-corrected volume flow measurements

OBJECTIVE

To explore changes in volume flow in the umbilical vein in healthy second-trimester fetuses.

METHODS

This was a prospective observational pilot study performed at Stavanger University Hospital, Norway, between May and October 2013. Serial three-dimensional ultrasound recordings from the umbilical vein were acquired every 30 s in a 5-min period in 43 fetuses at 17-20 weeks' gestation. The recordings were analyzed with pixelwise spatially angle-corrected volume flow measurements.

RESULTS

We observed variation in the umbilical vein volume flow in all fetuses, ranging from a mean minimum of 1.01 mL/s to a mean maximum of 2.60 mL/s. The minimum of all measurements was 57% compared with the mean value and the maximum was 148% of the mean value. The individual flow volume measurements ranged between 0.11 and 4.14 mL/s (mean, 1.76 mL/s). Within this range, an undulating course of all perfusion parameters was observed, with a full period of 4-5 min duration.

CONCLUSION

Healthy second-trimester fetuses show cyclical variation in blood flow in the umbilical vein. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Color-Doppler sonographic tissue perfusion measurements reveal significantly diminished renal cortical perfusion in kidneys with vesicoureteral reflux

Vesicoureteral reflux (VUR) and its sequelae may lead to reduced renal perfusion and loss of renal function. Methods to describe and monitor tissue perfusion are needed. We investigated dynamic tissue perfusion measurement (DTPM) with the PixelFlux-software to measure microvascular changes in the renal cortex in 35 children with VUR and 28 healthy children. DTPM of defined horizontal slices of the renal cortex was carried out. A kidney was assigned to the “low grade reflux”-group if the reflux grade of the voiding cystourethrogram was 1 to 3 and to the “high grade reflux”-group if the reflux grade was 4 to 5. Kidneys with VUR showed a significantly reduced cortical perfusion. Compared to healthy kidneys, this decline reached in low and high grade refluxes within the proximal 50% of the cortex: 3% and 12 %, in the distal 50% of the cortex: 21% and 44 % and in the most distal 20 % of the cortex 41% and 44%. DTPM reveals a perfusion loss in kidneys depending on the degree of VUR, which is most pronounced in the peripheral cortex. Thus, DTPM offers the tool to evaluate microvascular perfusion, to help planning treatment decisions in children with VUR.

Imaging of renal cell carcinoma

Renal cell carcinoma (RCC) is the most common kidney cancer in adults. Early and accurate imaging plays an important role in the detection, staging, and follow-up of RCC. Patient care and case management revolves heavily around diagnostic imaging so it is imperative that appropriate and adequate imaging is acquired. There are well-established standard imaging protocols available to patients and their providers, although at the same time, there is also extensive ongoing research on improving the various modalities. Ultrasound has been the most commonly used imaging technique for renal imaging in general. However, computed tomography (CT) is the first choice for imaging of renal masses, and has been the mainstay for several decades. High resolution, reproducibility, reasonable preparation and acquisition time, and acceptable cost allow CT to remain as the primary choice for radiologic imaging. Magnetic resonance imaging (MRI) is considered as an important alternative in patients requiring further imaging or in cases of allergies, pregnancy, or surveillance. With increasing concern over radiation exposure, there has been a trend toward the higher use of MRI. It is important to understand the various imaging options available, as well as the current status of and results from recent RCC imaging studies. In this review we discuss these modalities, including the current state of ultrasound, CT, and MRI in RCC.

ZIRK-Technique: Zero Ischemia Resection in the Kidney for High-Risk Renal Masses: Perioperative Outcome

OBJECTIVES

This study evaluates the feasibility and safety of open-partial nephrectomies in the ZIRK-technique (Zero Ischemia Resection in the Kidney) for renal masses with high-risk anatomical features--objectified by the PADUA score.

METHODS

We identified 40 consecutive cases of partial nephrectomies performed without clamping of the renal artery in our department of urology. Retrospective analysis of the preoperative CT or MRI scans showed 27 cases with a PADUA score ≥8, of which 15 cases had a score ≥10. Cases were in particular assessed regarding operation time (ORT), estimated blood loss (EBL), surgical margins and postoperative complications using the Clavien classification.

RESULTS

The mean age of the study population was 67.6 years with an average BMI of 26.8 kg/m2. The mean ORT was 1:46 with an average EBL of 521 ml. Clavien grade II complications were observed seven times, while 3 patients had a grade IIIa complication. Despite complex and adverse location of the tumors, nephron-sparing surgery without ischemia could be performed with negative surgical margins for all cases. EBL, transfusion rate and complication were considerably more frequent in high-risk tumors.

CONCLUSION

Highly complex renal tumors, PADUA ≥10, can be resected in ZIRK-technique with good operative outcome and a low complication rate.