CT perfusion technique for assessment of early kidney allograft dysfunction: preliminary results

Objectives

To assess the benefit of quantitative computed tomography (CT) perfusion for differentiating acute tubular necrosis (ATN) and acute rejection (AR) in kidney allografts.

Methods

Twenty-two patients with acute kidney allograft dysfunction caused by either AR (n?=?6) or ATN (n?=?16) were retrospectively included in the study. All patients initially underwent a multiphase CT angiography (CTA) protocol (12 phases, one phase every 3.5 s) covering the whole graft to exclude acute postoperative complications. Multiphase CT dataset and dedicated software were used to calculate renal blood flow. Renal biopsy or clinical course of disease served as the standard of reference. Mean effective radiation dose and mean amount of contrast media were calculated.

Results

Renal blood flow values were significantly lower (P?=?0.001) in allografts undergoing AR (48.3?±?21 ml/100 ml/min) compared with those with ATN (77.5?±?21 ml/100 ml/min). No significant difference (P?=?0.71) was observed regarding creatinine level with 5.65?±?3.1 mg/dl in AR and 5.3?±?1.9 mg/dl in ATN. The mean effective radiation dose of the CT perfusion protocol was 13.6?±?5.2 mSv; the mean amount of contrast media applied was 34.5?±?5.1 ml. All examinations were performed without complications.

Conclusion

CT perfusion of kidney allografts may help to differentiate between ATN and rejection.

Key points

? Quantitative CT perfusion of renal transplants is feasible. ? CT perfusion could help to non-invasively differentiate AR from ATN. ? CT perfusion might make some renal biopsies unnecessary.     

T1-mapping for assessment of ischemia-induced acute kidney injury and prediction of chronic kidney disease in mice

Objectives

To investigate whether T1-mapping allows assessment of acute kidney injury (AKI) and prediction of chronic kidney disease (CKD) in mice.

Methods

AKI was induced in C57Bl/6N mice by clamping of the right renal pedicle for 35 min (moderate AKI, n?=?26) or 45 min (severe AKI, n?=?23). Sham animals served as controls (n?=?9). Renal histology was assessed in the acute (day 1?+?day 7; d1?+?d7) and chronic phase (d28) after AKI. Furthermore, longitudinal MRI-examinations (prior to until d28 after surgery) were performed using a 7-Tesla magnet. T1-maps were calculated from a fat-saturated echoplanar inversion recovery sequence, and mean and relative T1-relaxation times were determined.

Results

Renal histology showed severe tubular injury at d1?+?d7 in both AKI groups, whereas, at d28, only animals with prolonged 45-min ischemia showed persistent signs of AKI. Following both AKI severities T1-values significantly increased and peaked at d7. T1-times in the contralateral kidney without AKI remained stable. At d7 relative T1-values in the outer stripe of the outer medulla were significantly higher after severe than after moderate AKI (138?±?2 % vs. 121?±?3 %, p?=?0.001). T1-elevation persisted until d28 only after severe AKI. Already at d7 T1 in the outer stripe of the outer medulla correlated with kidney volume loss indicating CKD (r?=?0.83).

Conclusion

T1-mapping non-invasively detects AKI severity in mice and predicts further outcome.

Key Points

? Renal T1-relaxation times are increased after ischemia-induced acute kidney injury. ? Renal T1-values correlate with subsequent kidney volume loss. ? T1-mapping detects the severity of acute kidney injury and predicts further outcome.     

Diffusion-weighted imaging of focal renal lesions: a meta-analysis

Objectives

Contrast-enhanced MRI can only distinguish to a limited extent between malignant and benign focal renal lesions. The aim of this meta-analysis is to review renal diffusion-weighted imaging (DWI) to compare apparent diffusion coefficient (ADC) values for different renal lesions that can be applied in clinical practice.

Methods

A PubMed search was performed to identify relevant articles published 2004–2011 on renal DWI of focal renal lesions. ADC values were extracted by lesion type to determine whether benign or malignant. The data table was finalised in a consensus read. ADC values were evaluated statistically using meta-regression based on a linear mixed model. Two-sided P value <5 % indicated statistical significance.

Results

The meta-analysis is based on 17 studies with 764 patients. Renal cell carcinomas have significant lower ADC values than benign tissue (1.61?±?0.08?×?10^-3 mm²/s vs 2.10?±?0.09?×?10^-3 mm²/s; P?<?0.0001). Uroepithelial malignancies can be differentiated by lowest ADC values (1.30?±?0.11?×?10^-3 mm²/s). There is a significant difference between ADC values of renal cell carcinomas and oncocytomas (1.61?±?0.08?×?10^-3 mm²/s vs 2.00?±?0.08?×?10^-3 mm²/s; P?<?0.0001).

Conclusions

Evaluation of ADC values can help to determine between benign and malignant lesions in general but also seems able to differentiate oncocytomas from malignant tumours, hence potentially reducing the number of unnecessarily performed nephrectomies.

Key Points

? This meta-analysis assesses the role of diffusion-weighted MRI in renal lesions. ? ADC values obtained by DW MRI have been compared for different renal lesions. ? ADC values can help distinguish between benign and malignant tumours. ? Differentiating oncocytomas from malignant tumours can potentially reduce inappropriate nephrectomies.     

Comparison of ASL and DCE MRI for the non-invasive measurement of renal blood flow: quantification and reproducibility

Objectives

To investigate the reproducibility of arterial spin labelling (ASL) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and quantitatively compare these techniques for the measurement of renal blood flow (RBF).

Methods

Sixteen healthy volunteers were examined on two different occasions. ASL was performed using a multi-TI FAIR labelling scheme with a segmented 3D-GRASE imaging module. DCE MRI was performed using a 3D-FLASH pulse sequence. A Bland-Altman analysis was used to assess repeatability of each technique, and determine the degree of correspondence between the two methods.

Results

The overall mean cortical renal blood flow (RBF) of the ASL group was 263?±?41 ml min^?1 [100 ml tissue]^?1, and using DCE MRI was 287?±?70 ml min^?1 [100 ml tissue]^?1. The group coefficient of variation (CV_g) was 18 % for ASL and 28 % for DCE-MRI. Repeatability studies showed that ASL was more reproducible than DCE with CV_gs of 16 % and 25 % for ASL and DCE respectively. Bland-Altman analysis comparing the two techniques showed a good agreement.

Conclusions

The repeated measures analysis shows that the ASL technique has better reproducibility than DCE-MRI. Difference analysis shows no significant difference between the RBF values of the two techniques.

Key Points

? Reliable non-invasive monitoring of renal blood flow is currently clinically unavailable. ? Renal arterial spin labelling MRI is robust and repeatable. ? Renal dynamic contrast-enhanced MRI is robust and repeatable. ? ASL blood flow values are similar to those obtained using DCE-MRI.     

Magnetisation transfer MR imaging of the kidney: evaluation at 3.0 T in association with renal function

Objective

To evaluate the feasibility of using magnetisation transfer (MT) MRI of the kidney at 3.0 T to assess renal function.

Methods

Forty-four patients who underwent abdominal MRI on a 3.0-T system including gradient-echo (GRE) sequences with and without MT pulse were included. In each patient, MT ratio (MTR) of the renal cortex and medulla was measured by using regions of interest (ROIs) placed on the MTR map image.

Results

Regression analysis showed good correlation between estimated glomerular filtration rate (eGFR) and MTR of the renal cortex (r?=??0.645, P?<?0.0001). Among 44 patients, 22 were categorised as the normal renal function group and 22 were classified as the decreased eGFR group. The mean MTR of the renal cortex in patients with decreased eGFR (mean MTR, 30.7?±?3.2 %) was significantly higher (P?<?0.0001) than that in patients with normal renal function (mean MTR, 25.3?±?2.2 %), although the mean MTRs of the renal medulla in the two groups were not significantly different.

Conclusion

There was good correlation between eGFR and MTR of the renal cortex derived from MT MRI at 3.0 T. This technique may have the potential to evaluate the degree of renal function non-invasively in patients with renal impairment.

Key Points

? Magnetisation transfer techniques can provide new information about renal disease. ? MTR values of the renal cortex correlate well with estimated glomerular filtration. ? Higher MTR of the renal cortex exists in patients with renal dysfunction. ? MT MRI at 3.0 T may be useful for evaluating renal function.     

Improved measurement of the glomerular filtration rate from Tc-99m DTPA scintigraphy in patients following nephrectomy

Objective

We aimed to improve Tc-99m DTPA glomerular filtration rate (GFR) scintigraphy (Gates’ method) in a prospective study using Cr-51 EDTA GFR test as a gold standard.

Methods

Fifty-seven Tc-99m DTPA GFR scintigrams in 45 subjects (male/female?=?33:12, age?=?45.9?±?17.6 years, 14 healthy volunteers and 31 nephrectomised patients) were compared using Cr-51 EDTA GFR tests. Using the %renal uptake of Tc-99m DTPA and Cr-51 EDTA GFR, a revised equation for GFR was established through linear regression analysis.

Results

The revised equation for improved GFR was GFR(mL/min)?=?(%renal uptake?×?11.7773)???0.7354. Gates’ original GFRs (70.1?±?20.5 mL/min/1.73 m²) were significantly lower than Cr-51 EDTA GFRs (97.0?±?31.9 mL/min/1.73 m²; P?<?0.0001), but the improved GFRs (98.0?±?26.3 mL/min/1.73 m²) were not different from (P?=?0.7360) and had a significant correlation with (r?=?0.73, P?<?0.0001) the Cr-51 EDTA GFRs. The revised GFR equation effectively demonstrated perioperative GFR changes in kidneys that were operated on and the contralateral kidneys at 3 and 6 months post-partial nephrectomy (n?=?25).

Conclusions

GFR measurement using Tc-99m DTPA scintigraphy could be significantly improved by a revised equation derived from the comparison with Cr-51 EDTA GFR.

Key Points

? Measurement of glomerular filtration rate is difficult following nephrectomy. ? Measurements can be significantly improved by new renal sctintigraphic methods. ? This helps physicians to measure kidney function of patients following nephrectomy. ? Management of renal tumour patients should become more effective.     

A trucut biopsy needle for bipolar radiofrequency ablation of needle tract: a proof-of-concept experiment

Objective

To develop a trucut biopsy needle featuring two electrodes that allow for bipolar radiofrequency (RF) coagulation of the puncture tract.

Methods

We modified a 14-G trucut biopsy needle to contain two insulated electrodes and connected the device to an RF generator. Biopsies in ex vivo porcine liver and kidney were performed. The puncture tract was coagulated by using different RF energy settings (5 W, 10 W, 20 W). Tissue specimens were dissected along the puncture tract and the coagulation area was macroscopically evaluated. CT-guided in vivo liver and kidney biopsies were performed in two domestic pigs. Lengths of specimens were measured. Post-biopsy contrast-enhanced CT examinations were performed to rule out biopsy-related bleeding. Animals were euthanised and coagulation areas macroscopically explored.

Results

The mean diameters of the coagulated area around the ex vivo biopsy tract were 4.2?±?1.1 mm (5 W), 6.0?±?2.0 mm (10 W) and 5.2?±?0.51 mm (20 W) in liver and 5.0?±?0.7 mm (5 W), 6.6?±?0.9 (10 W) and 6.0?±?2.0 mm (20 W) in kidney. After biopsies CT revealed no bleeding. Mean maximum coagulation diameters were 10.1?±?4.6 mm (10 W) in liver and 6.0?±?2.5 mm (10 W) in kidney. Mean length of the specimens was 12.2?±?4.4 mm in kidney and 11.1?±?3.6 mm in liver tissue.

Conclusion

Bipolar RF biopsy is a promising tool for tract coagulation after percutaneous biopsy.     

Safety of meglumine gadoterate (Gd-DOTA)-enhanced MRI compared to unenhanced MRI in patients with chronic kidney disease (RESCUE study)

Objective

To prospectively compare the renal safety of meglumine gadoterate (Gd-DOTA)-enhanced magnetic resonance imaging (MRI) to a control group (unenhanced MRI) in high-risk patients.

Methods

Patients with chronic kidney disease (CKD) scheduled for MRI procedures were screened. The primary endpoint was the percentage of patients with an elevation of serum creatinine levels, measured 72?±?24 h after the MRI procedure, by at least 25 % or 44.2 μmol/l (0.5 mg/dl) from baseline. A non-inferiority margin of the between-group difference was set at ?15 % for statistical analysis of the primary endpoint. Main secondary endpoints were the variation in serum creatinine and eGFR values between baseline and 72?±?24 h after MRI and the percentage of patients with a decrease in eGFR of at least 25 % from baseline. Patients were screened for signs of nephrogenic systemic fibrosis (NSF) at 3-month follow-up.

Results

Among the 114 evaluable patients, one (1.4 %) in the Gd-DOTA-MRI group and none in the control group met the criteria of the primary endpoint [Δ?=??1.4 %, 95%CI = (?7.9 %; 6.7 %)]. Non-inferiority was therefore demonstrated (P?=?0.001). No clinically significant differences were observed between groups for the secondary endpoints. No serious safety events (including NSF) were noted.

Conclusion

Meglumine gadoterate did not affect renal function and was a safe contrast agent in patients with CKD.

Key points

? Contrast-induced nephropathy (CIN) is a potential problem following gadolinium administration for MRI. ? Meglumine gadoterate (Gd-DOTA) appears safe, even in patients with chronic kidney disease. ? Gd-DOTA only caused a temporary creatinine level increase in 1/70 such patients. ? No case or sign of NSF was detected at 3-month follow-up.     

Acoustic radiation force impulse (ARFI) in the evaluation of the renal parenchymal stiffness in paediatric patients with vesicoureteral reflux: preliminary results

Objectives

To prospectively evaluate acoustic radiation force impulse (ARFI) imaging of the kidneys in children with and without chronic renal disease.

Methods

Twenty-eight children (age range 9–16 years) with primary or secondary vesicoureteral reflux (≥ grade III) underwent scintigraphy and ultrasound with ARFI. Kidneys were divided—according to scintigraphy—into “affected” and “contralateral”; the results were compared with 16 age-matched healthy subjects. An ARFI value, expressed as speed (m/s) of wave propagation through the tissue, was calculated for each kidney through the mean of the values obtained at the upper, middle and lower third. The Wilcoxon test was used; P values <0.05 were considered statistically significant.

Results

The mean ARFI values obtained in the “affected” kidneys (5.70?±?1.71 m/s) were significantly higher than those measured in both “contralateral” (4.09?±?0.97, P?<?0.0001) and “healthy” kidneys (3.13?±?0.09, P?<?0.0001). The difference between values in the “contralateral” kidneys and “healthy” ones was significant (P?<?0.0001). The “affected” kidneys with secondary reflux had mean ARFI values (6.59?±?1.45) significantly higher than those with primary reflux (5.35?±?1.72).

Conclusions

ARFI values decrease from kidneys with secondary vesicoureteral reflux to kidneys with primary reflux to unaffected kidneys contralateral to reflux to normal kidneys.

Key points

? Acoustic radiation force impulse (ARFI) can quantify tissue elasticity during ultrasound examinations. ? Kidneys are highly heterogeneous and difficult to evaluate with ARFI. ? Kidneys damaged by vesicoureteral reflux are stiffer than normal. ? ARFI can identify initial damage in macroscopically normal kidneys.     

Appendiceal length as an independent risk factor for acute appendicitis

Objectives

To determine if appendiceal lengths differ between adults with acute appendicitis and asymptomatic controls.

Methods

In vivo appendiceal length at computed tomography (CT) in 321 adults with surgically proven appendicitis was compared with that in 321 consecutive asymptomatic adult controls. CT length was derived using curved multiplanar reformats along the long axis. Gross pathological length provided external validation for appendectomy cases.

Results

Appendiceal length at CT correlated well with appendicitis specimens (mean length, 6.8 cm vs 6.6 cm; 79 % within 1.5 cm). For asymptomatic controls, mean CT appendiceal length was 7.9 cm, longer in men (8.4?±?3.8 vs 7.4?±?3.1 cm; P?=?0.02), matching closely historical normative post-mortem data. The mean and standard deviation of appendiceal length at CT were significantly greater among negative controls than in the positive appendicitis group (7.9?±?3.5 vs 6.8?±?1.9 cm; P?=?0.03). Of appendicitis cases, 90 % (288/321) fell within the range 4.0–10.0 cm, compared with 59 % (189/321) of negative controls (P?<?0.001). Among controls, a fivefold increase in appendixes >10 cm and a twofold increase in appendixes <4 cm were observed. Half (9/18) of long appendicitis cases showed tip appendicitis at CT.

Conclusions

“Intermediate” appendiceal lengths (4–10 cm) are more frequently complicated by acute appendicitis, whereas both “long” (>10 cm) and “short” (<4 cm) lengths are more frequently observed in unaffected adults.

Key Points

? “Long” (>10 cm) appendices are more frequently observed in asymptomatic adults. ? In cases of acute appendicitis, 90 % measure 4–10 cm in length. ? Measurement of appendiceal length at computed tomography correlates well with gross pathology. ? Tip appendicitis is more common among long appendixes.     

A prospective feasibility study of sub-millisievert abdominopelvic CT using iterative reconstruction in Crohn’s disease

Objective

Iterative reconstruction (IR) allows diagnostic CT imaging with less radiation exposure than filtered back projection (FBP). We studied an IR low-dose CT abdomen/pelvis (LDCTAP) protocol, designed to image at an effective dose (ED) approximating 1 mSv in patients with Crohn’s disease (CD).

Methods

Forty patients, mean age 37?±?13.4 years (range 17–69), with CD underwent two synchronous CT protocols (conventional-dose (CDCTAP) and LDCTAP). CDCTAP and LDCTAP images were compared for diagnostic acceptability, yield, image quality and ED (in millisieverts). The optimal level of IR for LDCTAP was also studied.

Results

LDCTAP yielded a mean ED of 1.3?±?0.8 mSv compared with 4.7?±?2.9 mSv for CDCTAP, reducing ED by 73.7?±?3.3 % (mean dose reduction, 3.5?±?2.1 mSv; P?<?0.001) and dose length product by 73.6?±?2.6 % (P?<?0.001). Sub-millisievert (0.84 mSv) imaging was performed for patients with a body mass index (BMI) less than 25 (i.e. 63 % of our cohort). LDCTAP resulted in increased image noise and reduced diagnostic acceptability compared with CDCTAP despite use of IR, but detection of extra-luminal complications was comparable.

Conclusion

Patients with suspected active CD can be adequately imaged using LDCTAP, yielding comparable information regarding extent, activity and complications of CD compared with CDCTAP, but with 74 % less dose. LDCTAP at doses equivalent to that of two abdominal radiographs represents a feasible alternative to CDCTAP.

Key points

? Radiation dose is a concern when imaging patients with Crohn’s disease. ? New techniques allow low-dose abdominopelvic CT with acceptable image quality. ? Using hybrid iterative reconstruction, its diagnostic yield compares well with that of conventional CT. ? Sub-millisievert CT of patients with Crohn’s disease appears technically and clinically feasible.     

Evaluation of 100 brain examinations using a 3 Tesla MR-compatible incubator—safety, handling, and image quality

Introduction

Several studies have revealed the importance of brain imaging in term and preterm infants. The aim of this retrospective study was to review safety, handling, and image quality of MR brain imaging using a new 3 Tesla MR-compatible incubator.

Methods

Between 02/2011 and 05/2012 100 brain MRIs (84 infants, mean gestational age 32.2?±?4.7 weeks, mean postmenstrual age at imaging 40.6?±?3.4 weeks) were performed using a 3 Tesla MR-compatible incubator with dedicated, compatible head coil. Seventeen examinations (13 infants, mean gestational age 35.1?±?5.4 weeks, mean postmenstrual age at imaging 47.8?±?7.4 weeks) with a standard head coil served as a control. Image analysis was performed by a neuroradiologist and a pediatric radiologist in consensus.

Results

All but two patients with known apnea were transferred to the MR unit and scanned without problems. Handling was easier and faster with the incubator; relevant motion artifacts (5.9 vs. 10.8 %) and the need for repetitive sedation (43.0 vs. 86.7 %) were reduced. Considering only images not impaired by motion artifacts, image quality (4.8?±?0.4 vs. 4.3?±?0.8, p?=?0.047) and spatial resolution (4.7?±?0.4 vs. 4.2?±?0.6, p?=?0.011) of T2-weighted images were scored significantly higher in patients imaged with the incubator. SNR increased significantly (171.6?±?54.5 vs. 80.5?±?19.8, p?<?0.001) with the use of the incubator.

Conclusion

Infants can benefit from the use of a 3 Tesla MR-compatible incubator because of its safety, easier, and faster handling (compared to standard imaging) and possibility to obtain high-quality MR images even in unstable patients.     

Upright Cone CT of the hindfoot: Comparison of the non-weight-bearing with the upright weight-bearing position

Objectives

To prospectively compare computed tomography (CT) of the hindfoot in the supine non-weight-bearing position (NWBCT) with upright weight-bearing position (WBCT).

Methods

Institutional review board approval and informed consent of all patients were obtained. NWBCT and WBCT scans of the ankle were obtained in 22 patients (mean age, 46.0?±?17.1 years; range 19–75 years) using a conventional 64-row CT for NWBCT and a novel cone-beam CT for WBCT. Two musculoskeletal radiologists independently performed the following measurements: the hindfoot alignment angle, fibulocalcaneal and tibiocalcaneal distances, lateral talocalcaneal joint space width, talocalcaneal overlap and naviculocalcaneal distance. Significant changes between NWBCT and WBCT were sought using Wilcoxon signed-rank test. P values <0.05 were considered statistically significant.

Results

Significant differences were found for all measurements except the hindfoot alignment angle and tibiocalcaneal distance. Significant measurement results were as follows (NWBCT/WBCT reader 1; NWBCT/WBCT reader 2, mean ± standard deviation): fibulocalcaneal distance 3.6 mm?±?5.2/0.3 mm?±?6.0 (P?=?0.006); 1.4 mm?±?6.3/-1.1 mm?±?6.3 (P?=?0.002), lateral talocalcaneal joint space width 2.9 mm?±?1.7/2.2 mm?±?1.1 (P?=?0.005); 3.4 mm?±?1.9/2.4 mm?±?1.3 (P?=?0.001), talocalcaneal overlap 4.1 mm?±?3.9/1.4 mm?±?3.9 (P?=?0.001); 4.5 mm?±?4.3/1.4 mm?±?3.7 (P?<?0.001) and naviculocalcaneal distance 13.5 mm?±?4.0/15.3 mm?±?4.7 (P?=?0.037); 14.0 mm?±?4.4/15.7 mm?±?6.2 (P?=?0.100). Interreader agreement was good to excellent (ICC 0.48–0.94).

Conclusion

Alignment of the hindfoot significantly changes in the upright weight-bearing CT position. Differences can be visualised and measured using WBCT.

Key Points

? Cone-beam computed tomography (CBCT) offers new opportunities for musculoskeletal problems ? Visualization and quantification of hindfoot alignment are possible in upright weight-bearing CBCT ? Hindfoot alignment changes significantly from non-weight-bearing to weight-bearing CT ? The weight-bearing position leads to a decrease in the fibulocalcaneal distance and talocalcaneal overlap ? The naviculocalcaneal distance is increased in the weight-bearing position     

C-arm CT during hepatic arteriography tumour-to-liver contrast: intraindividual comparison of three different contrast media application protocols

Objective

To compare tumour-to-liver contrast (TLC) of C-arm CT during hepatic arteriography (CACTHA) acquired using three protocols in patients with HCC.

Methods

This prospective study was IRB approved and informed consent was obtained from each patient. Twenty-nine patients (mean age, 68?±?7 years; 27 men) with 55 HCCs (mean diameter, 2.6?±?1.5 cm) underwent three different CACTHA protocols in random order before chemoembolisation. Contrast medium (100 mg iodine/ml) was injected into the common hepatic artery (flow rate 4 ml/s). The imaging delay for the start of the CACTHA examination was 4 s (protocol A), 8 s (protocol B) and 12 s (protocol C) (total amount of injected contrast medium: 48 ml, 64 ml, 80 ml). TLC was measured by placing regions of interest (ROIs) in the HCC and liver parenchyma. Mixed model ANOVAs and Bonferroni corrected post hoc tests were used for statistical analysis.

Results

Mean values for TLC were 132?±?3.3 HU, 186?±?5.8 HU and 168?±?2.8 HU for protocols A, B and C. Protocol B provided significantly higher TLC than protocols A and C (p?<?0.001).

Conclusion

TLC was significantly higher using an imaging delay of 8 s compared with a delay of 4 or 12 s.

Key Points

? C-arm cone-beam CT (CACT) angiography offers additional information during hepatic intervention. ? CACT hepatic arteriography tumour-to-liver contrast is highest with an 8-s delay. ? An 8-s delay is recommended for early arterial phase CACTHA for hepatocelullar carcinoma.     

Clinical impact of hyperattenuation of adrenal glands on contrast-enhanced computed tomography of polytraumatised patients

Objective

To evaluate the prognostic value of hyperattenuating adrenal glands on contrast-enhanced CT of polytraumatised patients.

Methods

Two hundred ninety-two patients (195 men and 97 women, mean age 45.3?±?23.3 years) were included in this retrospective study. CT examinations were performed 60 s after intravenous injection of contrast material. Image analysis was performed by two radiologists. Patients were assigned to one of two groups according to the attenuation of the adrenal gland [group 1: adrenal glands ≥ inferior vena cava (IVC); group 2: adrenal glands < IVC].

Results

Eighteen patients (42.2 years?±?24.2) were assigned to group 1 and 274 patients (48.4 years?±?22.4) to group 2. The average adrenal density was 150.8?±?36.1 HU in group 1 and 83.7?±?23.6 HU in group 2 (P?<?0.0001). Eight of the 18 patients in group 1 (44.4 %) and 33 of the 274 patients in group 2 (12.4 %) died during hospitalisation (P?<?0.05). Mean adrenal enhancement was significantly higher in patients who died (101.9?±?40.6 HU) compared with survivors (86.1?±?27.0 HU; P?<?0.001).

Conclusion

Hyperattenuation of adrenal glands is associated with a higher mortality rate in polytraumatised patients and may serve as a predictor of poor clinical outcome.

Key points

? Hyperattenuating adrenal glands can be observed in 6.2 % of polytraumatised patients. ? Hyperattenuating adrenal glands indicate poor clinical outcome in polytraumatised patients. ? In polytraumatised patients, hyperattenuating adrenal glands are associated with a high mortality rate. ? Adrenal enhancement is higher amongst patients who died than amongst survivors.     

Contrast agent bolus tracking with a fixed threshold or a manual fast start for coronary CT angiography

Objectives

Comparison of bolus tracking with a fixed threshold versus a manual fast start for coronary CT angiography.

Methods

We retrospectively analysed 320-row coronary CT angiography of 50 patients with suspected or known coronary artery disease. Twenty-five examinations were initiated by a bolus tracking method (group 1), 25 examinations with a manual fast surestart (group 2).

Results

Mean attenuation values in the ascending aorta were 519?±?111 Hounsfield units (HU) in group 1 and 476?±?65 HU in group 2 (p?=?0.10). Assessable vessel lengths were 171?±?44 mm vs 172?±?29 mm for the right coronary artery (p?=?0.91), 11?±?4 mm vs 12?±?4 mm for the left main (p?=?0.9), 163?±?28 mm vs 151?±?26 mm for the left anterior descending coronary artery (p?=?0.11) and 125?±?41 mm vs 110?±?37 mm for the left circumflex coronary artery (p?=?0.18). Image quality for all coronary arteries was not significantly different between the groups (p?>?0.41). The attenuation ratio between the left and right ventricle was 2.8?±?0.7 vs 3.6?±?1.0 (p?=?0.003). Significantly less contrast agent was used in group 2 (64?±?6 ml vs 80?±?0 ml; p?<?0.001).

Conclusions

Bolus tracking with a fixed threshold and with a manual fast start are both suitable methods; the fast start allowed a reduction of contrast agent volumes.

Key Points

? Fixed threshold bolus tracking is suitable for coronary 320-row CT angiography ? Manual fast start bolus tracking can reduce contrast agent volumes ? Manual fast start and fixed threshold initiation achieve good image quality ? Fixed threshold bolus tracking achieves a more reliable contrast bolus position     

Chronic mitral regurgitation detected on cardiac MDCT: differentiation between functional and valvular aetiologies

Objective

To determine whether cardiac computed tomography (MDCT) can differentiate between functional and valvular aetiologies of chronic mitral regurgitation (MR) compared with echocardiography (TTE).

Methods

Twenty-seven patients with functional or valvular MR diagnosed by TTE and 19 controls prospectively underwent cardiac MDCT. The morphological appearance of the mitral valve (MV) leaflets, MV geometry, MV leaflet angle, left ventricular (LV) sphericity and global/regional wall motion were analysed. The coronary arteries were evaluated for obstructive atherosclerosis.

Results

All control and MR cases were correctly identified by MDCT. Significant differences were detected between valvular and control groups for anterior leaflet length (30?±?7 mm vs. 22?±?4 mm, P?<?0.02) and thickness (3.0?±?1 mm vs. 2.2?±?1 mm, P?<?0.01). High-grade coronary stenosis was detected in all patients with functional MR compared with no controls (P?<?0.001). Significant differences in those with/without MV prolapse were detected in MV tent area (?1.0?±?0.6 mm vs. 1.3?±?0.9 mm, P?<?0.0001) and MV tent height (?0.7?±?0.3 mm vs. 0.8?±?0.8 mm, P?<?0.0001). Posterior leaflet angle was significantly greater for functional MR (37.9?±?19.1° vs. 22.9?±?14°, P?<?0.018) and less for valvular MR (0.6?±?35.5° vs. 22.9?±?14°, P?<?0.017). Sensitivity, specificity, and positive and negative predictive values of MDCT were 100%, 95%, 96% and 100%.

Conclusion

Cardiac MDCT allows the differentiation between functional and valvular causes of MR.     

Evaluation of Split Renal Function Before and After Renal Arterial Embolization for Angiomyolipoma Using Absolute Ethanol

Purpose

Transcatheter arterial embolization (TAE) with absolute ethanol is widely accepted as a therapeutic procedure for renal angiomyolipoma (AML). We aim to evaluate the split renal function before and after AE for renal AML by using 99m-technetium (^99mTc)-mercaptoacetyltriglycine 3 (MAG3) renography.

Methods

This study was approved by the Institutional Review Board. The study population comprised 11 renal AML patients (three males, eight females, age 55.1 ± 13.8 years, AML in eight right and three left kidneys) who received unilateral renal TAE with absolute ethanol from April 2002 to January 2013. Blood renal function (i.e. serum creatinine and estimated glomerular filtration rate [eGFR] and split effective renal plasma flow [ERPF]) calculated on ^99mTc-MAG3 renography was compared before and within 1 week after renal AE. Statistical analysis was calculated using Wilcoxon signed-ranked test.

Results

TAE for renal AML was technically successful in all patients. Serum creatinine and eGFR did not change before and after TAE. ERPF on the embolized kidney did not change before (127.3 ± 60.8 ml/min) and after (127.6 ± 47.4 ml/min) TAE (p = 0.9726). ERPF on the nonembolized kidney showed a statistically significant increase before (152.5 ± 46.8 ml/min) and within 1 week after (169.1 ± 41.5 ml/min) TAE (p = 0.0093 and p < 0.05, respectively).

Conclusion

TAE for renal AML may not induce renal dysfunction on the embolized kidney and may immediately increase the renal blood flow of the nonembolized kidney.     

Does Renal Artery Supply Indicate Treatment Success of Renal Denervation?

Purpose

Renal denervation (RDN) emerged as an innovative interventional antihypertensive therapy. With the exception of pretreatment blood pressure (BP) level, no other clear predictor for treatment efficacy is yet known. We analyzed whether the presence of multiple renal arteries has an impact on BP reduction after RDN.

Methods

Fifty-three patients with treatment-resistant hypertension (office BP ≥ 140/90 mmHg and 24-h ambulatory BP monitoring (≥130/80 mmHg) underwent bilateral catheter-based RDN. Patients were stratified into one-vessel (OV) (both sides) and at least multivessel (MV) supply at one side. Both groups were treated on one vessel at each side; in case of multiple arteries, only the dominant artery was treated on each side.

Results

Baseline clinical characteristics (including BP, age, and estimated glomerular filtration rate) did not differ between patients with OV (n = 32) and MV (n = 21). Office BP was significantly reduced in both groups at 3 months (systolic: OV ?15 ± 23 vs. MV ?16 ± 20 mmHg; diastolic: OV ?10 ± 12 vs. MV ?8 ± 11 mmHg, both p = NS) as well as 6 months (systolic: OV ?18 ± 18 vs. MV ?17 ± 22 mmHg; diastolic: OV ?10 ± 10 vs. ?10 ± 12 mmHg, both p = NS) after RDN. There was no difference in responder rate (rate of patients with office systolic BP reduction of at least 10 mmHg after 6 months) between the groups.

Conclusion

In patients with multiple renal arteries, RDN of one renal artery—namely, the dominant one—is sufficient to induce BP reduction in treatment-resistant hypertension.     

Percutaneous transthoracic needle biopsy of small (≤1 cm) lung nodules under C-arm cone-beam CT virtual navigation guidance

Objectives

To describe our initial experience with percutaneous transthoracic needle biopsy (PCNB) of small (≤1 cm) lung nodules using a cone-beam computed tomography (CBCT) virtual navigation guidance system in 105 consecutive patients.

Methods

One hundred and five consecutive patients (55 male, 50 female; mean age, 62 years) with 107 small (≤1 cm) lung nodules (mean size, 0.85 cm?±?0.14) underwent PCNBs under CBCT virtual-navigation guidance system and constituted our study population. Procedural details—including radiation dose, sensitivity, specificity, diagnostic accuracy and complication rates of CBCT virtual navigation guided PCNBs—were described.

Results

The mean number of pleural passages with the coaxial needle, biopsies, CT acquisitions, total procedure time, coaxial introducer dwelling time, and estimated radiation exposure during PCNBs were 1.03?±?0.21, 3.1?±?0.7, 3.4?±?1.3, 10.5 min?±?3.2 and 7.2 min?±?2.5, and 5.72 mSv?±?4.19, respectively. Sixty nodules (56.1 %) were diagnosed as malignant, 38 (35.5 %) as benign and nine (8.4 %) as indeterminate. The sensitivity, specificity, and diagnostic accuracy of CBCT virtual-navigation-guided PCNB for small (≤1 cm) nodules were 96.7 % (58/60), 100 % (38/38) and 98.0 % (96/98), respectively. Complications occurred in 13 (12.1 %) cases; pneumothorax in seven (6.5 %) and haemoptysis in six (5.6 %).

Conclusion

CBCT virtual-navigation-guided PCNB is a highly accurate and safe diagnostic method for small (≤1 cm) nodules.

Key Points

? CBCT virtual-navigation guidance offers new biopsy options for lung nodules ? CBCT virtual-navigation-guided PCNB is highly accurate for small (≤1 cm) nodules ? CBCT virtual-navigation-guided PCNB for small (≤1 cm) nodules is safe ? Procedure time and radiation exposure of CBCT virtual-navigation-guided PCNB is reasonable