Effects of changes in analytic variables and contrast medium on estimation of glomerular filtration rates by computed tomography in healthy dogs

OBJECTIVE To investigate effects of changes in analytic variables and contrast medium osmolality on glomerular filtration rate estimated by CT (CT-GFR) in dogs. ANIMALS 4 healthy anesthetized Beagles. PROCEDURES GFR was estimated by inulin clearance, and dogs underwent CT-GFR with iodinated contrast medium (iohexol or iodixanol) in a crossover-design study. Dynamic renal CT scanning was performed. Patlak plot analysis was used to calculate GFR with the renal cortex or whole kidney selected as the region of interest. The renal cortex was analyzed just prior to time of the second cortical attenuation peak. The whole kidney was analyzed 60, 80, 100, and 120 seconds after the appearance of contrast medium. Automated GFR calculations were performed with preinstalled perfusion software including 2 noise reduction levels (medium and strong). The CT-GFRs were compared with GFR estimated by inulin clearance. RESULTS There was no significant difference in CT-GFR with iohexol versus iodixanol in any analyses. The CT-GFR at the renal cortex, CT-GFR for the whole kidney 60 seconds after appearance of contrast medium, and CT-GFR calculated by perfusion software with medium noise reduction did not differ significantly from GFR estimated by inulin clearance. The CT-GFR was underestimated at ≥ 80 seconds after contrast medium appearance (whole kidney) and when strong noise reduction was used with perfusion CT software. CONCLUSIONS AND CLINICAL RELEVANCE Selection of the renal cortex as region of interest or use of the 60-second time point for whole-kidney evaluation yielded the best CT-GFR results. The perfusion software used produced good results with appropriate noise reduction. IMPACT FOR HUMAN MEDICINE The finding that excessive noise reduction caused underestimation of CT-GFR suggests that this factor should also be considered in CT-GFR examination of human patients.

Aneurysm size and the Windkessel effect: An analysis of contrast intensity in digital subtraction angiography

Large cerebral aneurysms are considered more dangerous than their smaller counterparts, with higher risk of subarachnoid hemorrhage. Understanding the hemodynamics of large aneurysms has potential to predict their response to treatment. Digital subtraction angiography images for patients with intracranial aneurysms over a seven-year period were reviewed. Unruptured solitary aneurysms of the internal carotid artery (ICA) proximal to the terminus and posterior communicating artery were included. Contrast intensity over time was analyzed at the center of the M1 segment of the middle cerebral artery distal to the aneurysm and compared to the contralateral side. Analysis included time to peak (TP)10%-100% (time needed for contrast to change from 10% intensity to 100%), washout time (WT)100%-10% (time for 100% intensity to 10%), and quartile time (QT)25%-25% (time for 25% intensity during vessel filling to 25% during emptying). Fifty patients met the inclusion criteria. Analysis over the ipsilateral M1 segment revealed a significant increase in QT25%-25% (8.5 vs 7.6 seconds, p = 0.006) compared to the contralateral side. There was a correlation between TP10%-100% and QT25%-25% with aneurysm size (Pearson's r = 0.37, p = 0.007 and r = 0.43, p = 0.001, respectively). Larger ICA aneurysms were associated with delayed contrast intensity times . A plausible mechanism is that large aneurysms act as a capacitance chamber (Windkessel effect) that slow the arrival of contrast distal to the aneurysm. This may be of significance for large aneurysms after treatment, where the loss of the Windkessel effect places the distal circulation at greater risk for hemorrhage, and warrants further study.

Iohexol degradation in wastewater and urine by UV-based Advanced Oxidation Processes (AOPs): Process modeling and by-products identification

In this work, an Iodinated Contrast Medium (ICM), Iohexol, was subjected to treatment by 3 Advanced Oxidation Processes (AOPs) (UV, UV/H₂O₂, UV/H₂O₂/Fe²⁺). Water, wastewater and urine were spiked with Iohexol, in order to investigate the treatment efficiency of AOPs. A tri-level approach has been deployed to assess the UV-based AOPs efficacy. The treatment was heavily influenced by the UV transmittance and the organics content of the matrix, as dilution and acidification improved the degradation but iron/H₂O₂ increase only moderately. Furthermore, optimization of the treatment conditions, as well as modeling of the degradation was performed, by step-wise constructed quadratic or product models, and determination of the optimal operational regions was achieved through desirability functions. Finally, global chemical parameters (COD, TOC and UV-Vis absorbance) were followed in parallel with specific analyses to elucidate the degradation process of Iohexol by UV-based AOPs. Through HPLC/MS analysis the degradation pathway and the effects the operational parameters were monitored, thus attributing the pathways the respective modifications. The addition of iron in the UV/H₂O₂ process inflicted additional pathways beneficial for both Iohexol and organics removal from the matrix.

Single coronary artery arising from the right sinus of Valsalva presenting with chest pain

Single coronary artery is a rare anomaly, with a reported incidence of 0.024%. It can be diagnosed on coronary computed tomography angiography, where the presence of ostial narrowing and compression between the great vessels must be carefully excluded, since these malignant forms can lead to sudden cardiac death and other ischemic complications. We describe a case of single coronary artery arising from the right sinus of Valsalva presenting with symptoms of ischemic chest pain.

Association of TNF Receptor 2 and CRP with GFR Decline in the General Nondiabetic Population

BACKGROUND AND OBJECTIVES

Higher levels of inflammatory markers have been associated with renal outcomes in diabetic populations. We investigated whether soluble TNF receptor 2 (TNFR2) and high-sensitivity C-reactive protein (hsCRP) were associated with the age-related GFR decline in a nondiabetic population using measured GFR (mGFR).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A representative sample of 1590 middle-aged people from the general population without prevalent kidney disease, diabetes, or cardiovascular disease were enrolled in the Renal Iohexol-Clearance Survey in Tromsø 6 (RENIS-T6) between 2007 and 2009. After a median of 5.6 years, 1296 persons were included in the Renal Iohexol-Clearance Survey Follow-Up Study. GFR was measured using iohexol clearance at baseline and follow-up.

RESULTS

The mean decline of mGFR during the period was -0.84 ml/min per 1.73 m2 per year. There were 133 participants with rapid mGFR decline, defined as an annual mGFR loss >3.0 ml/min per 1.73 m2, and 26 participants with incident CKD, defined as mGFR<60 ml/min per 1.73 m2 at follow-up. In multivariable adjusted mixed models, 1 mg/L higher levels of hsCRP were associated with an accelerated decline in mGFR of -0.03 ml/min per 1.73 m2 per year (95% confidence interval [95% CI], -0.05 to -0.01), and 1 SD higher TNFR2 was associated with a slower decline in mGFR (0.09 ml/min per 1.73 m2 per year; 95% CI, 0.01 to 0.18). In logistic regression models adjusted for sex, age, weight, and height, 1 mg/L higher levels of hsCRP were associated with higher risk of rapid mGFR decline (odds ratio, 1.03; 95% CI, 1.01 to 1.06) and incident CKD (odds ratio, 1.04; 95% CI, 1.00 to 1.08).

CONCLUSIONS

Higher baseline levels of hsCRP but not TNFR2 were associated with accelerated age-related mGFR decline and incident CKD in a general nondiabetic population.

Optimization of window settings for standard and advanced virtual monoenergetic imaging in abdominal dual-energy CT angiography

OBJECTIVES

To determine the optimal window setting for displaying virtual monoenergetic reconstructions of third generation dual-source, dual-energy CT (DECT) angiography of the abdomen.

METHODS

Forty-five patients were evaluated with DECT angiography (90/150 kV, 180/90 ref. mAs). Three datasets were reconstructed: standard linear blending (M_0.6), 70 keV traditional virtual monoenergetic (M70), and 40 keV advanced noise-optimized virtual monoenergetic (M40+). The best window setting (width and level, W/L) was assessed by two blinded observers and was correlated with aortic attenuation to obtain the Optimized W/L setting (O-W/L). Subjective image quality was assessed, and vessel diameters were measured to determine any possible influences between different W/L settings. Repeated measures of variance were used to evaluate comparison of W/L values, image quality, and vessel sizing between M_0.6, M70, and M40+.

RESULTS

The Best W/L (B-W/L) for M70 and M40+ was 880/280 and 1410/450, respectively. Results from regression analysis inferred an O-W/L of 850/270 for M70 and 1350/430 for M40+. Significant differences for W and L were found between the Best and the Optimized W/L for M40+, and between M70 and M40+ for both the Best and Optimized W/L. No significant differences for vessel measurements were found using the O-W/L for M40+ compared to the standard M_0.6 (p ≥ 0.16), and significant differences were observed when using the B-W/L with M40+ compared to M_0.6 (p ≤ 0.04).

CONCLUSION

In order to optimize virtual monoenergetic imaging with both traditional M70 and advanced M40+, adjusting the W/L settings is necessary. Our results suggest a W/L setting of 850/270 for M70 and 1350/430 for M40+.

Nanopolymersomes with an Ultrahigh Iodine Content for High-Performance X-Ray Computed Tomography Imaging In Vivo

Biocompatible and biodegradable nanopolymersomes with an unprecedented iodine content, low viscosity, and iso-osmolality achieve significantly enhanced CT imaging of blood pool and the reticuloendothelial system. Moreover, in subcutaneous and orthotopic tumor models in mice, they show enhanced in vivo imaging when compared to iohexol, a clinically used small-molecule contrast agent.

Quantitative iodine content threshold for discrimination of renal cell carcinomas using rapid kV-switching dual-energy CT

PURPOSE

Determine iodine content threshold discriminating papillary renal cell carcinomas (pRCC) from complex cysts (CCs) using rapid kV-switching dual-energy CT (rsDECT).

MATERIALS AND METHODS

IRB-approved retrospective study of 72 consecutive patients with pathologic diagnosis of renal cell carcinoma, who underwent rsDECT from 2011 to 2015. Controls included consecutive patients with CC during same period. Iodine content of each pRCC (n = 27) was measured on rsDECT workstation for arterial (n = 15) or nephrographic phase (n = 12), and compared to iodine content for clear cell renal cell carcinomas (ccRCC, n = 46) and complex cysts (n = 54). An optimal iodine content threshold was estimated using logistic regressions and Youden's J based on maximum specificity and sensitivity.

RESULTS

Iodine threshold of 1.28 mg/cc was optimal to discriminate between pRCCs and CCs for nephrographic phase (sens 1.0, spec 0.96, PPV 0.92, and NPV 1.0, AUC 0.997, acc 0.97, p < 0.0001). Iodine threshold of 1.22 mg/cc was the optimal cutoff value to discriminate between pRCCs and CCs in the arterial phase (sens 0.67, spec 0.97, PPV 0.91, NPV 0.85, AUC 0.76, and acc 0.84, p = 0.006). The optimal threshold to discriminate between ccRCCs and pRCCs was 1.85 mg/cc in the arterial phase (sens 0.87, spec 0.92, PPV 0.87, NPV 0.92, p < 0001) and 2.71 mg/cc in the nephrographic phase (sens 1.0, spec 1.0, PPV 1.0, NPV 1.0, p < 0.0001).

CONCLUSIONS

Quantitative iodine values on rsDECT discriminate between papillary RCC and complex cysts, and between papillary RCC and clear cell RCC, the former addressing an important clinical challenge particularly when an unenhanced series has not been performed. These rsDECT thresholds differ from values derived from dual-source DECT technology.

Validity of simplified protocols to estimate glomerular filtration rate using iohexol clearance

Background: Iohexol clearance is an accurate and precise exogenous marker of glomerular filtration rate (GFR), but protocols are generally lengthy or require multiple sampling. Shorter or simpler protocols would be more practicable.

Methods: Two clearance estimates, two weeks apart, were undertaken in 11 healthy individuals and 26 diabetic patients with minimal to moderate renal impairment (chronic kidney disease stages 1-3). Blood specimens withdrawn at 60, 90, 120, 150, 180 and 240 min post-iohexol were analysed for iohexol.

Results: Visit 1 demonstrated excellent correlation with visit 2 (slope 1.00, confidence interval [CI] 0.88 to 1.13, intercept 0.94 mL/min/1.73 m2, CI -9.9 to 11.8, P=0.43). The within-individual coefficient of variation (CV) of the 240 min reference method was 5.4% at a mean GFR of 84.1 mL/min/1.73 m2. Single point estimates between 120 and 240 min had CVs of 4.5-7.0%, and did not differ from the reference method CV by more than 2.0 mL/min/1.73 m2. Two and three point estimates in the interval 60-120 min post iohexol injection offered no advantages over these single-point estimates and overestimated at lower GFRs.

Conclusions: An iohexol clearance estimate of GFR derived from a single sample taken between 2 to 4 h after infusion may provide a suitable tool for routine clinical use.

Differentiation of mass-forming intrahepatic cholangiocarcinoma from poorly differentiated hepatocellular carcinoma: based on the multivariate analysis of contrast-enhanced computed tomography findings

PURPOSE

We aim to gain further insight into identifying differential radiological features of mass-forming intrahepatic cholangiocarcinoma (mICC) from poorly differentiated hepatocellular carcinoma (pHCC) on contrast-enhanced computed tomography (CT).

MATERIALS AND METHODS

107 patients with pathologically confirmed mICC (n = 48) and pHCC (n = 59) who had undergone preoperative contrast-enhanced CT were enrolled. Qualitative analysis of CT images were evaluated for tumor demarcation, shape, presence of satellite nodules, capsular retraction, biliary involvement, intratumoral arteries, tortuous tumoral vessels, vascular invasion, portal vein tumor thrombus, arterial enhancement pattern, portal venous phase enhancement, and washout pattern. Quantitative analysis was performed for mean attenuation of tumor and tumor-to-liver contrast during each phase. The degree of arterial enhancement was graded based on quantitative measurements.

RESULTS

A lobulated shape, indistinct margin, peripheral rim enhancement in the arterial phase, and the presence of bile duct dilatation were CT features favoring mICC, whereas a round shape, partially indistinct margin, heterogeneous enhancement in the arterial phase, washout pattern and the presence of tortuous tumoral vessels were CT features favoring pHCC in the univariate analysis (P < 0.05). Tumor-to-liver contrast of pHCC was greater than that of mICC during the arterial phase (P = 0.015). In the multivariate analysis, bile duct dilatation, tortuous tumoral vessels, and a washout pattern were independent CT features for distinguishing between the two types. (P = 0.003, P = 0.003, P = 0.044, respectively).

CONCLUSION

The absence of a washout pattern and tortuous tumoral vessels and presence of bile duct dilatation are more indicative of mICC than of pHCC on contrast-enhanced CT.

Application of gemstone spectral imaging for efficacy evaluation in hepatocellular carcinoma after transarterial chemoembolization

AIM: To assess the value of gemstone spectral imaging (GSI) in efficacy evaluation in hepatocellular cancer (HCC) after transcatheter arterial chemoembolization (TACE) treatment.

METHODS: Thirty patients with HCC underwent GSI, including nonenhanced, arterial, portalvenous and delayed phase scans, after TACE treatment. Arterial phase images were acquired with GSI for reconstruction of virtual nonenhanced images and color overlay images. Digital subtraction angiography (DSA) was performed in all these patients. Two blinded and independent readers evaluated the data in two reading sessions; standard nonenhanced, arterial, portalvenous, and delayed phase images were read in session A, and the optimal monochromatic images, iodine/water based images and spectrum features were read in session B. Sensitivity and specificity were calculated with the DSA data as the reference standard. The sensitivity and specificity were compared using the χ² test.

RESULTS: DSA revealed 154 lesions in 30 patients, and 100 of them had blood supply. Overall sensitivity and specificity were 72% (72/100) and 77.8% (42/54) for session A, and 97% (97/100) and 94.4% (51/54) for session B, respectively. The sensitivity and specificity of the two reading sessions were significantly different (χ² = 23.04, χ² = 7.11, P < 0.05).

CONCLUSION: Compared with conventional CT, GSI could significantly improve the detection of small and multiple lesions without increasing the radiation dose. Based on spectrum features, GSI could assess tumor homogeneity and more accurately identify residual tumors and recurrent or metastatic lesions during efficacy evaluation and follow-up in HCC after TACE treatment.

Congenital portosystemic shunts with and without gastrointestinal bleeding - case series

BACKGROUND

The clinical presentation of congenital portosystemic shunt is variable and gastrointestinal bleeding is an uncommon presentation.

OBJECTIVE

To describe the imaging features of congenital portosystemic shunt as it presented in 11 children with (n = 6) and without gastrointestinal bleeding (n = 5).

MATERIALS AND METHODS

We performed a retrospective study on a clinical and imaging dataset of 11 children diagnosed with congenital portosystemic shunt.

RESULTS

A total of 11 children with congenital portosystemic shunt were included in this study, 7 with extrahepatic portosystemic shunts and 4 with intrahepatic portosystemic shunts. Six patients with gastrointestinal bleeding had an extrahepatic portosystemic shunt, and the imaging results showed that the shunts originated from the splenomesenteric junction (n = 5) or splenic vein (n = 1) and connected to the internal iliac vein. Among the five cases of congenital portosystemic shunt without gastrointestinal bleeding, one case was an extrahepatic portosystemic shunt and the other four were intrahepatic portosystemic shunts.

CONCLUSION

Most congenital portosystemic shunt patients with gastrointestinal bleeding had a shunt that drained portal blood into the iliac vein via an inferior mesenteric vein. This type of shunt was uncommon, but the concomitant rate of gastrointestinal bleeding with this type of shunt was high.

Percutaneous discal cyst rupture in a professional football player using sublaminar epidural injection for thecal sac displacement

A case of percutaneous discal cyst rupture in a 25-year-old professional American football player is reported. The patient presented with a 3-day history of severe left-sided back pain. Magnetic resonance imaging examination demonstrated a discal cyst effacing the left L4-L5 lateral recess, with interposed thecal sac. A sublaminar epidural injection was performed displacing the thecal sac, exposing the discal cyst, and allowing for percutaneous perforation. The patient had complete resolution of symptoms after discal cyst rupture and was able to compete in a professional football game 3 days later. Computed tomography-guided percutaneous rupture is a therapeutic modality that may be considered for treatment of a symptomatic discal cyst.

[Iohexol tracing of hyaluronic acid distribution in the knee joint cavity of rabbits]

OBJECTIVE

To investigate the distribution of hyaluronic acid (HA) with iohexol tracing in the knee joint cavity of rabbits using CT plain scan, three-dimensional reconstruction and Χ-ray and observe how different injection sites affect HA distribution.

METHODS

Mixtures of HA and iohexol (tracer) were prepared that contained final iohexol concentrations of 2.5%, 5%, 10%, 20%, or 40%. The HA-iohexol mixtures (0.5 ml) were injected into rabbit knee joints, and the optimal iohexol concentration that allowed clear differentiation of the injected agents from the surrounding tissues was determined using dual-source CT plain scan and three-dimensional reconstruction technique. The HA-iohexol mixture (0.5 ml) containing the optimal concentration of iohexol was then injected into the knees of the rabbits either through the patella medial approach or the medial joint line approach, and HA distribution in the knee joint cavity was observed using CT scan and Χ-ray.

RESULTS

The CT value of HA-iohexol mixture increased progressively with the tracer concentration. After injection of the mixture containing 2.5%, 5%, 10%, 20%, and 40% iohexol, the CT value ratios of the soft tissue, HA-iohexol mixture and bone cortex were 2:7:46, 2:14:44, 2:28:44, 2:60:46, and 2:98:45, respectively, and a iohexol concentration of 5% was determined as optimal for differntiating the injected agents from the surrounding tissues. The HA-iohexol mixutre containing 5% iohexol injected through the medial-patellar approach was distributed mainly over the patello-femoral joint, and that injected through the joint line approach was found mainly over the tibio-femoral joint.

CONCLUSION

HA-iohexol mixture containing 5% iohexol allows clear differentiation of bone cortex and soft tissues in rabit knee joint from the injected agents on CT scan and Χ-ray, and the injection approach can influence HA distribution in the knee joint cavity.

CHRONIC CEREBROSPINAL VENOUS INSUFFICIENCY--DISEASE OR MISDIAGNOSIS?

BACKGROUND AND PURPOSE

Former studies reported internal jugular vein stenosis in patients with multiple sclerosis. We aimed to evaluate if these venous stenoses were real and cerebral venous outflow of patients with multiple sclerosis differed from that of normal controls.

METHODS

20 controls were prospectively investigated by angiography and duplex ultrasound. Seven patients with multiple sclerosis underwent angiography at other centers; we reviewed these registrations and performed venous ultrasound examinations.

RESULTS

Angiography displayed > 50% stenosis of internal jugular vein in 19 controls (69 ± 17% on the right and 73 ± 13% on the left side) and < 50% stenosis in 1 control (43.5% and 44.6%). All 7 patients had at least one-sided stenosis. The mean degree of stenosis was 63 ± 16% on the right and 67 ± 13% on the left side. There was no significant difference in the degree of stenosis between patients and controls. However, these "stenoses" disappeared if the contrast agent was injected at a catheter position below the orifice of the subclavian vein during venography. The venous flow volume was also similar between groups: 479.7 ± 214.1 and 509.8 ± 212.0 ml/min (right and left side) in the patients and 461.3 ± 224.3 and 513.6 ± 352.2 ml/min in the control group; p = 0.85 and 0.98 (right and left). Color and power duplex imaging also revealed normal blood flow of the internal jugular vein in all patients and controls.

CONCLUSION

The cerebral venous status of patients with multiple sclerosis and controls were similar. The angiographic "stenoses" were virtual, caused by the contrast dilution effect of the non-contrast blood stream of the subclavian vein.

Characterization of early disease status in treatment-naive male paediatric patients with Fabry disease enrolled in a randomized clinical trial

Trial Design

This analysis characterizes the degree of early organ involvement in a cohort of oligo-symptomatic untreated young patients with Fabry disease enrolled in an ongoing randomized, open-label, parallel-group, phase 3B clinical trial.

Methods

Males aged 5–18 years with complete α-galactosidase A deficiency, without symptoms of major organ damage, were enrolled in a phase 3B trial evaluating two doses of agalsidase beta. Baseline disease characteristics of 31 eligible patients (median age 12 years) were studied, including cellular globotriaosylceramide (GL-3) accumulation in skin (n = 31) and kidney biopsy (n = 6; median age 15 years; range 13–17 years), renal function, and glycolipid levels (plasma, urine).

Results

Plasma and urinary GL-3 levels were abnormal in 25 of 30 and 31 of 31 patients, respectively. Plasma lyso-GL-3 was elevated in all patients. GL-3 accumulation was documented in superficial skin capillary endothelial cells (23/31 patients) and deep vessel endothelial cells (23/29 patients). The mean glomerular filtration rate (GFR), measured by plasma disappearance of iohexol, was 118.1 mL/min/1.73 m² (range 90.4–161.0 mL/min/1.73 m²) and the median urinary albumin/creatinine ratio was 10 mg/g (range 4.0–27.0 mg/g). On electron microscopy, renal biopsy revealed GL-3 accumulation in all glomerular cell types (podocytes and parietal, endothelial, and mesangial cells), as well as in peritubular capillary and non-capillary endothelial, interstitial, vascular smooth muscle, and distal tubules/collecting duct cells. Lesions indicative of early Fabry arteriopathy and segmental effacement of podocyte foot processes were found in all 6 patients.

Conclusions

These data reveal that in this small cohort of children with Fabry disease, histological evidence of GL-3 accumulation, and cellular and vascular injury are present in renal tissues at very early stages of the disease, and are noted before onset of microalbuminuria and development of clinically significant renal events (e.g. reduced GFR). These data give additional support to the consideration of early initiation of enzyme replacement therapy, potentially improving long-term outcome.

Trial Registration

ClinicalTrials.gov NCT00701415

Optimal flushing agents for integrated optical and acoustic imaging systems

An increasing number of integrated optical and acoustic intravascular imaging systems have been developed and hold great promise for accurately diagnosing vulnerable plaques and guiding atherosclerosis treatment. However, in any intravascular environment, the vascular lumen is filled with blood, a high-scattering source for optical and high-frequency ultrasound signals. Blood must be flushed away to provide clearer images. To our knowledge, no research has been performed to find the ideal flushing agent for combined optical and acoustic imaging techniques. We selected three solutions as potential flushing agents for their image-enhancing effects: mannitol, dextran, and iohexol. Testing of these flushing agents was performed in a closed-loop circulation model and in vivo on rabbits. We found that a high concentration of dextran was the most useful for simultaneous intravascular ultrasound and optical coherence tomography imaging.

Iohexol versus diatrizoate for fecal/fluid tagging during CT colonography performed with cathartic preparation: comparison of examination quality

OBJECTIVE

We aimed to compare iohexol vs. diatrizoate as fecal/fluid tagging agents for computed tomography colonography (CTC) regarding examination quality.

METHODS

Forty prospective patients (M:F = 23:17; 63 ± 11.6 years) received CTC using 50 mL (350 mgI/mL) oral iohexol for tagging. Forty other indication-matched, age-matched, and sex-matched patients who underwent CTC using 100 mL diatrizoate for tagging and otherwise the same technique, were retrospectively identified. Two groups were compared regarding overall examination quality, per-patient and per-segment scores of colonic bubbles (0 [no bubbles] to 5 [the largest amount]), and the volume, attenuation, and homogeneity (untagged, layered, and homogeneous) of the residual colonic fluid.

RESULTS

The iohexol group demonstrated a greater amount of colonic bubbles than the diatrizoate group: mean per-patient scores ± SD of 1.2 ± 0.8 vs. 0.7 ± 0.6, respectively (p = 0.003); and rates of segments showing ≥ grade 3 bubbles of 12.9 % (85/659) vs. 1.6 % (11/695), respectively (p = 0.001). Residual colonic fluid amount standardized to the colonic volume did not significantly differ: 7.2 % ± 4.2 vs. 7.8 % ± 3.7, respectively (p = 0.544). Tagged fluid attenuation was mostly comparable between groups and the fluid was homogeneously tagged in 98.7 % (224/227) vs. 99.5 % (218/219) segments, respectively (p = 0.344). Iohexol caused more colonic bubbles when used during cathartic CTC. Otherwise, examination quality was similarly adequate with both iohexol and diatrizoate.

KEY POINTS

• When used for tagging, iohexol caused significantly more colonic bubbles than diatrizoate. • The residual colonic fluid amount did not significantly differ between iohexol and diatrizoate. • The quality of fluid tagging was similarly adequate in both iohexol and diatrizoate.

CT texture analysis of renal masses: pilot study using random forest classification for prediction of pathology

RATIONALE AND OBJECTIVES

Computed tomography texture analysis (CTTA) allows quantification of heterogeneity within a region of interest. This study investigates the possibility of distinguishing between several common renal masses using CTTA-derived parameters by developing and validating a predictive model.

MATERIALS AND METHODS

CTTA software was used to analyze 20 clear cell renal cell carcinomas (RCCs), 20 papillary RCCs, 20 oncocytomas, and 20 renal cysts. Regions of interest were drawn around each mass on multiple slices in the arterial, venous, and delayed phases on renal mass protocol CT scans. Unfiltered images and spatial band-pass filtered images were analyzed to quantify heterogeneity. Random forest method was used to construct a predictive model to classify lesions using quantitative parameters. The model was externally validated on a separate set of 19 unknown cases.

RESULTS

The random forest model correctly categorized oncocytomas in 89% of cases (sensitivity = 89%, specificity = 99%), clear cell RCCs in 91% of cases (sensitivity = 91%, specificity = 97%), cysts in 100% of cases (sensitivity = 100%, specificity = 100%), and papillary RCCs in 100% of cases (sensitivity = 100%, specificity = 98%).

CONCLUSIONS

CTTA, in conjunction with random forest modeling, demonstrates promise as a tool to characterize lesions. Various renal masses were accurately classified using quantitative information derived from routine scans.

Computed tomography to diagnose blunt diaphragm injuries: not ready for prime time

Diaphragm injuries after blunt trauma are uncommon but require early diagnosis to expedite repair. The advancing technology of computed tomography (CT) scanners has improved the detection of almost all traumatic injuries; however, the literature regarding the diagnostic accuracy of CT scan for blunt diaphragm injuries is lacking. The purpose of this study was to determine the CT scan findings in the setting of known blunt diaphragm injury. We performed a retrospective review of all blunt trauma patients with a known diaphragm injury confirmed at laparotomy who also had a preoperative CT scan of the torso. Every CT scan was retrospectively reviewed by a board-certified radiologist for evidence of diaphragm injury as well as associated abdominal and thoracic injuries. Forty-two patients sustaining blunt trauma had preoperative CT scans of the torso and a diaphragm injury confirmed at laparotomy. Only 57 per cent of CT scans showed evidence of diaphragmatic injury. The most common thoracic injury identified was a pulmonary contusion (79%). Although the advancement of imaging technology has markedly improved the diagnosis and management of blunt traumatic injuries, the detection of diaphragm injuries using CT continues to be low and reconstructions do not help in finding diaphragm injuries.

Revised Choi imaging criteria correlate with clinical outcomes in patients with metastatic renal cell carcinoma treated with sunitinib

PURPOSE

To compare revised Choi criteria that incorporate concurrent size and attenuation changes at early follow-up imaging with Response Evaluation Criteria in Solid Tumors ( RECIST Response Evaluation Criteria in Solid Tumors ) 1.1 and original Choi criteria in stratification of clinical outcomes in patients with metastatic renal cell carcinoma ( mRCC metastatic renal cell carcinoma ) treated with sunitinib.

MATERIALS AND METHODS

Institutional review board approved this retrospective study and waived informed consent. Baseline and first follow-up computed tomographic scans in 69 patients (50 men, 19 women; mean age, 60.3 years; range, 19-83 years) with mRCC metastatic renal cell carcinoma treated with sunitinib from October 1, 2008, to March 1, 2013, were evaluated for tumor response by using RECIST Response Evaluation Criteria in Solid Tumors 1.1, original Choi criteria, and revised Choi criteria. Correlations with overall survival ( OS overall survival ) and progression-free survival ( PFS progression-free survival ) were compared and stratified according to each radiologic criteria with Kaplan-Meier and multivariate Cox regression analysis.

RESULTS

Median follow-up time was 29.7 months (95% confidence interval [ CI confidence interval ]: 18.9, 45.9). Response according to revised Choi criteria was independently correlated with OS overall survival (hazard ratio, 0.47 [95% CI confidence interval : 0.23, 0.99]; P = .046) and PFS progression-free survival (hazard ratio, 0.53 [95% CI confidence interval : 0.29, 0.99]; P = .047). Response according to RECIST Response Evaluation Criteria in Solid Tumors was not significantly correlated with OS overall survival (hazard ratio, 0.65 [95% CI confidence interval : 0.27, 1.58]; P = .344) or PFS progression-free survival (hazard ratio, 0.89 [95% CI confidence interval : 0.42, 1.91]; P = .768). Response according to original Choi criteria was not significantly correlated with OS overall survival (hazard ratio, 0.60 [95% CI confidence interval : 0.32, 1.11]; P = .106) or PFS progression-free survival (hazard ratio, 0.59 [95% CI confidence interval : 0.34, 1.02]; P = .060). Median OS overall survival and PFS progression-free survival in responders according to revised Choi criteria was 39.4 months (95% CI confidence interval : 9.1, upper limit not estimated) and 13.7 months (95% CI confidence interval : 6.4, 24.6), respectively, compared with 12.8 months (95% CI confidence interval : 8.7, 18.0) and 5.3 months (95% CI confidence interval : 3.9, 8.4), respectively, in nonresponders.

CONCLUSION

Contemporaneous reduction in tumor size and attenuation were correlated with favorable clinical outcomes. Response according to revised Choi criteria showed better correlation with clinical outcomes compared with that according to RECIST Response Evaluation Criteria in Solid Tumors or original Choi criteria in patients with mRCC metastatic renal cell carcinoma treated with sunitinib.

Value of short-interval computed tomography when sonography fails to visualize the appendix and shows otherwise normal findings

OBJECTIVES

The purpose of this study was to evaluate the type and incidence of disorders revealed by short-interval computed tomography (CT) in patients with suspected appendicitis after graded compression sonography fails to reveal the appendix and shows otherwise normal findings.

METHODS

Computed tomographic findings and clinical courses were assessed retrospectively for 318 patients identified consecutively in a searchable database who met inclusion criteria specifying that sonography was the initial imaging examination for suspected appendicitis; sonography revealed nonvisualization of the appendix and otherwise normal results; and abdominopelvic CT was performed within 48 hours after sonography.

RESULTS

Of the 318 patients, short-interval CT revealed normal findings in 250 (78.6%). Appendicitis was revealed in 52 (16.4%) others, of whom 7 had perforation and all of whom had pathologic results confirming these CT findings. Important alternative diagnoses other than appendicitis were revealed in 16 (5.0%) others, including 2 (0.6%) who required urgent surgery and 14 (4.4%) who did not. No significant differences were observed between adult patients (>18 years) and pediatric patients.

CONCLUSIONS

Most short-interval CT scans in this clinical setting reveal normal findings, and relatively few disclose appendicitis or disorders that require urgent surgery. In view of concerns regarding radiation exposure associated with CT, these observations argue for the development of clinical triage methods that differentiate patients who are likely to benefit from short-interval postsonography CT from those who are not.

Stylomandibular tunnel widening versus narrowing: a useful tool in evaluating suprahyoid mass lesions

AIM

To evaluate whether qualitative and quantitative assessments of stylomandibular tunnel asymmetry are useful in lesion localization and differentiation.

MATERIALS AND METHODS

The stylomandibular tunnel was measured in 60 control patients at CT to determine normal side-to-side variation. Twenty-one patients in the study group with suprahyoid neck masses were divided into two subgroups, those with widening and those with narrowing of the pathological side. Surgical and pathological findings in these subgroups were compared for site of origin and histology.

RESULTS

Stylomandibular tunnel diameters in the control group had a mean variation of 0.9 mm (range: 0-3 mm, SD: 0.83 mm). Two-tailed t-test yielded a p-value of 0.018 for a variation of 3 mm and this was chosen as the threshold for disease. The widened stylomandibular tunnel group all had parotid gland lesions extending into the pre-styloid parapharyngeal space. The narrowed stylomandibular tunnel group had adenopathy, schwannomas, and paragangliomas/glomus vagale tumours arising from the post-styloid parapharyngeal space.

CONCLUSION

Qualitative assessment for asymmetry of the stylomandibular tunnel surpass the 3 mm threshold for pathology. Widening of the stylomandibular tunnel is primarily from deep lobe parotid lesions extending into the pre-styloid parapharyngeal space. Narrowing of the stylomandibular tunnel can be from adenopathy, schwannomas, and paragangliomas arising from the post-styloid parapharyngeal space.

Dual-phase CT findings of groove pancreatitis

PURPOSE

Groove pancreatitis is a rare focal form of chronic pancreatitis that occurs in the pancreaticoduodenal groove between the major and minor papillae, duodenum and pancreatic head. Radiologic appearance and clinical presentation can result in suspicion of malignancy rendering pancreaticoduodenectomy inevitable. This study reports dual phase CT findings in a series of 12 patients with pathology proven groove pancreatitis.

MATERIALS AND METHODS

Retrospective review of preoperative CT findings in 12 patients with histologically proven groove pancreatitis after pancreaticoduodenectomy. Size, location, attenuation, presence of mass or cystic components in the pancreas, groove and duodenum, calcifications, duodenal stenosis and ductal changes were recorded. Clinical data, laboratory values, endoscopic ultrasonographic and histopathological findings were collected.

RESULTS

Soft tissue thickening in the groove was seen in all patients. Pancreatic head, groove and duodenum were all involved in 75% patients. A discrete lesion in the pancreatic head was seen in half of the patients, most of which appeared hypodense on both arterial and venous phases. Cystic changes in pancreatic head were seen in 75% patients. Duodenal involvement was seen in 92% patients including wall thickening and cyst formation. The main pancreatic duct was dilated in 7 patients, with an abrupt cut off in 3 and a smooth tapering stricture in 4. Five patients had evidence of chronic pancreatitis with parenchymal calcifications.

CONCLUSION

Presence of mass or soft tissue thickening in the groove with cystic duodenal thickening is highly suggestive of groove pancreatitis. Recognizing common radiological features may help in diagnosis and reduce suspicion of malignancy.

Performance of formulas for estimating glomerular filtration rate in Indigenous Australians with and without Type 2 diabetes: the eGFR Study

AIMS

It has been proposed that the Chronic Kidney Disease Epidemiology Collaboration formula estimates glomerular filtration rate more accurately than the Modification of Diet in Renal Disease formula. With the very high incidence of diabetes and end-stage kidney disease in Indigenous Australians, accurate estimation of glomerular filtration rate is vital in early detection of kidney disease. We aimed to assess the performance of the Chronic Kidney Disease Epidemiology Collaboration, Modification of Diet in Renal Disease and Cockcroft-Gault formulas in Indigenous Australians with and without diabetes.

METHODS

Indigenous Australians with (n = 224) or without (n = 340) Type 2 diabetes had a reference glomerular filtration rate measure using plasma disappearance of iohexol (measured glomerular filtration rate) over 4 h. Serum creatinine was measured by an enzymatic method. Performance was assessed by bias (measured glomerular filtration rate - estimated glomerular filtration rate) and accuracy (percentage of estimated glomerular filtration rate within 30% of measured glomerular filtration rate).

RESULTS

The median measured glomerular filtration rate (interquartile range) in participants with or without diabetes was 97 (68-119) and 108 (90-122) ml min(-1)  1.73 m(-2) , respectively. The Chronic Kidney Disease Epidemiology Collaboration formula had smaller bias and greater accuracy than the Modification of Diet in Renal Disease and Cockcroft-Gault formulas overall, for participants both with and without diabetes. However, for estimated glomerular filtration rate > 90 ml min(-1)  1.73 m(-2) , the Chronic Kidney Disease Epidemiology Collaboration formula had greater bias in participants with diabetes, underestimating measured glomerular filtration rate by 7.4 vs. 1.0 ml min(-1)  1.73 m(-2) in those without diabetes. The Chronic Kidney Disease Epidemiology Collaboration formula was less accurate across the whole range of estimated glomerular filtration rates in participants with vs. those without diabetes (87.1% vs. 93.3%).

CONCLUSIONS

The Chronic Kidney Disease Epidemiology Collaboration formula outperforms the Modification of Diet in Renal Disease and Cockcroft-Gault formulas overall in Indigenous Australians with and without diabetes. However, the Chronic Kidney Disease Epidemiology Collaboration formula has greater bias in people with diabetes compared with those without diabetes, especially in those with normal renal function.