Abdominal CT: an intra-individual comparison between virtual monochromatic spectral and polychromatic 120-kVp images obtained during the same examination

OBJECTIVES

To compare quantitative and subjective image quality between virtual monochromatic spectral (VMS) and conventional polychromatic 120-kVp imaging performed during the same abdominal computed tomography (CT) examination.

MATERIALS AND METHODS

Our institutional review board approved this prospective study; each participant provided written informed consent. 51 patients underwent sequential fast kVp-switching dual-energy (80/140 kVp, volume CT dose index: 12.7 mGy) and single-energy (120-kVp, 12.7 mGy) abdominal enhanced CT over an 8 cm scan length with a random acquisition order and a 4.3-s interval. VMS images with filtered back projection (VMS-FBP) and adaptive statistical iterative reconstruction (so-called hybrid IR) (VMS-ASIR) (at 70 keV), as well as 120-kVp images with FBP (120-kVp-FBP) and ASIR (120-kVp-ASIR), were generated from dual-energy and single-energy CT data, respectively. The objective image noises, signal-to-noise ratios and contrast-to-noise ratios of the liver, kidney, pancreas, spleen, portal vein and aorta, and the lesion-to-liver and lesion-to-kidney contrast-to-noise ratios were measured. Two radiologists independently and blindly assessed the subjective image quality. The results were analyzed using the paired t-test, Wilcoxon signed rank sum test and mixed-effects model with Bonferroni correction.

RESULTS

VMS-ASIR images were superior to 120-kVp-FBP, 120-kVp-ASIR and VMS-FBP images for all the quantitative assessments and the subjective overall image quality (all P<0.001), while VMS-FBP images were superior to 120-kVp-FBP and 120-kVp-ASIR images (all P<0.004).

CONCLUSIONS

VMS images at 70 keV have a higher image quality than 120-kVp images, regardless of the application of hybrid IR. Hybrid IR can further improve the image quality of VMS imaging.

Optimizing image contrast display improves quantitative stenosis measurement in heavily calcified coronary arterial segments on coronary CT angiography: A proof-of-concept and comparison to quantitative invasive coronary angiography

RATIONALE AND OBJECTIVES

Blooming artifact from calcified plaques often renders measurement of stenosis impossible on coronary computed tomographic angiography (CTA). We sought to evaluate the impact of modifying window level on reducing blooming artifact, and its impact on stenosis quantification.

MATERIALS AND METHODS

We analyzed 125 calcified segments from 53 patients who underwent CTA and invasive coronary angiography (ICA). Segmental stenosis on CTA was measured using three window settings: width of 1000 Hounsfield units (HU) and level of 200 HU ("default"), 1500/200 HU ("widened"), and width and level based on the mean HU of the calcified plaque and pericoronary fat ("calcium-specific"). Segmental stenosis on ICA was quantified by a blinded experienced reader.

RESULTS

ICA found ≥50% stenosis in 30 segments. Displaying segments with widened and calcium-specific settings improved overall accuracy of detecting ≥50% stenosis (P's < 0.001) by increasing the rate of accurately quantifying <50% stenosis (P's < 0.001), and improved correlation of stenosis quantification to ICA (P's < 0.05). There was no difference in stenosis quantification accuracy between widened and calcium-specific window settings. Limits of agreement between CTA stenosis quantification and ICA narrowed with widened and calcium-specific settings.

CONCLUSIONS

We showed for the first time that in calcified segments, widening display window width significantly improved CTA quantification of stenosis compared to ICA.

Leukemias involving abdominal and pelvic lymph nodes: evaluation with contrast-enhanced MDCT

PURPOSE

To clarify features of lymph nodes associated with leukemia purposing to offer help for imaging diagnosis and differential diagnosis of leukemia.

MATERIALS AND METHODS

We retrospectively analyzed 47 patients with clinically proven leukemia involving the abdominal and pelvic lymph nodes. Of these 47 patients, 10 had acute myeloid leukemia, 9 had acute lymphocytic leukemia, and 28 had chronic lymphocytic leukemia. MDCT was used to determine lymph node features such as morphology, growth patterns, size, enhancement patterns, anatomical distribution, and manifestations in extramedullary organs.

RESULTS

Incidence of leukemia was higher in men than in women. Enlarged lymph nodes were more frequently conglomerated in chronic lymphocytic leukemia (96.4%) than in acute myeloid leukemia (50%) and acute lymphocytic leukemia (55.6%; P < 0.05 for both). Lymph nodes associated with chronic lymphocytic leukemia were larger than those associated with acute myeloid and lymphocytic leukemias (P < 0.05 for both). The enlarged lymph nodes appeared homogeneous (80.9%) and homogeneous mixed with peripheral (19.1%). No statistically significant differences were observed between the three types of leukemias with respect to enhancement patterns (all P > 0.05). The lymph nodes commonly associated with these three leukemias were located in the lesser omentum, upper and lower para-aortic regions, and groin region.

CONCLUSIONS

Our study showed that contrast-enhanced MDCT could accurately determine the enhancement patterns and anatomical distribution of lymph nodes associated with leukemia. Therefore, it is helpful for imaging diagnosis and differential diagnosis of leukemia.

Factors affecting glomerular filtration rate, as measured by iohexol disappearance, in men with or at risk for HIV infection

OBJECTIVE

Formulae used to estimate glomerular filtration rate (GFR) underestimate higher GFRs and have not been well-studied in HIV-infected (HIV(+)) people; we evaluated the relationships of HIV infection and known or potential risk factors for kidney disease with directly measured GFR and the presence of chronic kidney disease (CKD).

DESIGN

Cross-sectional measurement of iohexol-based GFR (iGFR) in HIV(+) men (n = 455) receiving antiretroviral therapy, and HIV-uninfected (HIV(-)) men (n = 258) in the Multicenter AIDS Cohort Study.

METHODS

iGFR was calculated from disappearance of infused iohexol from plasma. Determinants of GFR and the presence of CKD were compared using iGFR and GFR estimated by the CKD-Epi equation (eGFR).

RESULTS

Median iGFR was higher among HIV(+) than HIV(-) men (109 vs. 106 ml/min/1.73 m(2), respectively, p = .046), and was 7 ml/min higher than median eGFR. Mean iGFR was lower in men who were older, had chronic hepatitis C virus (HCV) infection, or had a history of AIDS. Low iGFR (≤90 ml/min/1.73 m(2)) was associated with these factors and with black race. Other than age, factors associated with low iGFR were not observed with low eGFR. CKD was more common in HIV(+) than HIV(-) men; predictors of CKD were similar using iGFR and eGFR.

CONCLUSIONS

iGFR was higher than eGFR in this population of HIV-infected and -uninfected men who have sex with men. Presence of CKD was predicted equally well by iGFR and eGFR, but associations of chronic HCV infection and history of clinically-defined AIDS with mildly decreased GFR were seen only with iGFR.

Outcomes and indications for intervention in non-operative management of paediatric liver trauma: a 5 year retrospective study

AIM

To determine the applicability of accurate computed tomography (CT) evaluation and embolization as non-operative management for liver trauma in a paediatric population.

MATERIAL AND METHODS

A retrospective observational study of 37 children (mean age 10.5 years) with hepatic trauma (28 blunt, 9 penetrating) admitted to a trauma referral centre over a 5 year period. All patients were evaluated with CT and scored with an Association for the Surgery of Trauma score. Inpatient information was reviewed for demographics, associated injuries, modes of management, efficacy and complications of management, and outcome.Statistical analysis was performed.

RESULTS

There were seven contusions, two grade I, two grade II, nine grade III, and 17 grade IV liver lacerations. Only two patients (grade IV, penetrating) underwent surgery for the management of bowel perforation. All children had non-surgical treatment of their liver trauma: three cases (grade IV) had primary angiography due to CT evidence of active bleeding and embolization was performed in two of these. Seven patients (two grade III, five grade IV)had angiography during the follow-up for evidence of a complicating pseudoaneurysm and embolization was performed in six of them. Embolization was successful in all the children; one minor complication occurred (cholecystitis). Endoscopic retrograde cholangiopancreatography (ERCP) plus stenting was performed in two cases for a bile leak. All 37 children had a positive outcome.

CONCLUSION

The present study demonstrates that non-operative management of hepatic trauma is applicable to children and may have a higher success rate than in adults.

Angiography-assisted computed tomography for the detection and intervention of a subtle aneurysm of the omentum

Intra-abdominal hemorrhage caused by omental artery rupture is a rare condition traditionally diagnosed via exploratory laparotomy in hemodynamically unstable patients. We experienced a case in which contrast-enhanced multidetector computed tomography (MDCT) and digital subtraction angiography did not identify the rupture site, whereas CT during left omental arteriography depicted a small 4-mm aneurysm. The lesion was then embolized with microcoils and N-butyl cyanoacrylate lipiodol glue. We consider that performing a CT during selective arteriography could be useful in cases in which the rupture site is unclear with other imaging techniques such as contrast-enhanced MDCT and digital subtraction angiography.

Combined biochemical and cytological analysis of membrane trafficking using lectins

We have tested the application of high-mannose-binding lectins as analytical reagents to identify N-glycans in the early secretory pathway of HeLa cells during subcellular fractionation and cytochemistry. Post-endoplasmic reticulum (ER) pre-Golgi intermediates were separated from the ER on Nycodenz-sucrose gradients, and the glycan composition of each gradient fraction was profiled using lectin blotting. The fractions containing the post-ER pre-Golgi intermediates are found to contain a subset of N-linked α-mannose glycans that bind the lectins Galanthus nivalis agglutinin (GNA), Pisum sativum agglutinin (PSA), and Lens culinaris agglutinin (LCA) but not lectins binding Golgi-modified glycans. Cytochemical analysis demonstrates that high-mannose-containing glycoproteins are predominantly localized to the ER and the early secretory pathway. Indirect immunofluorescence microscopy revealed that GNA colocalizes with the ER marker protein disulfide isomerase (PDI) and the COPI coat protein β-COP. In situ competition with concanavalin A (ConA), another high-mannose specific lectin, and subsequent GNA lectin histochemistry refined the localization of N-glyans containing nonreducing mannosyl groups, accentuating the GNA vesicular staining. Using GNA and treatments that perturb ER-Golgi transport, we demonstrate that lectins can be used to detect changes in membrane trafficking pathways histochemically. Overall, we find that conjugated plant lectins are effective tools for combinatory biochemical and cytological analysis of membrane trafficking of glycoproteins.

Ultrasound versus palpation guidance for intra-articular injections in patients with degenerative osteoarthritis of the elbow

OBJECTIVES

The aim of this study is to evaluate the accuracy rate of ultrasound (US) -guided intra-articular (IA) injections in patients by posterior approach with osteoarthritis (OA) of the elbow.

METHODS

Eighty patients with physical examination and radiographic findings of elbow OA were included. After US-guided IA or palpation-guided IA injection of iohexol contrast by posterior approach into the elbow joint, fluoroscopic images were obtained to ascertain whether the injected material had reached the IA space.

RESULTS

Of the 40 injections performed by US guidance, 40 were confirmed to have been placed in the IA space (an accuracy rate of 100%). Thirty-one of the 40 injections performed by the palpation guidance were IA space (77.5% accuracy rate).

CONCLUSIONS

US-guided IA elbow injections by posterior approach may raise the accuracy rate in elbow joint injections.

Intra-abdominal fibromatosis: differentiation from gastrointestinal stromal tumour based on biphasic contrast-enhanced CT findings

AIM

To identify the computed tomography (CT) criteria that differentiate intra-abdominal fibromatosis (IAF) from gastrointestinal stromal tumour (GIST).

MATERIALS AND METHODS

CT images of 34 pathologically proven cases of IAF (n = 15) and GIST (n = 19) were retrospectively reviewed. Location, contour, border, enhancement pattern, presence of necrosis, vessels, and air within the lesion were analysed. Long diameter (LD), short diameter (SD), LD/SD ratio, degree of enhancement, and lesion/aorta (L/A) CT attenuation ratio were measured and calculated. Significant CT criteria were identified using Fisher's exact test, grouped t-test, and receiver operating characteristic (ROC) curve. Sensitivity and specificity values were calculated when single or multiple CT criteria were used.

RESULTS

Extra-gastrointestinal location, ovoid or irregular contour, homogeneous enhancement, absence of intra-lesional necrosis, lower degree of enhancement, and L/A CT attenuation ratio differentiated IAF from GIST (p < 0.05). When any three of these eight criteria were combined, the sensitivity and specificity for diagnosing IAF were 100% (15 of 15) and 89.5% (17 of 19), respectively.

CONCLUSION

The following eight CT criteria are helpful to differentiate IAF from GIST: extra-gastrointestinal location, ovoid or irregular contour, homogeneous enhancement, absence of intra-lesional necrosis, a degree of enhancement of less than 40.5 HU in the arterial phase versus 46.5 HU in the portal venous phase, and an L/A CT attenuation ratio <0.315 in the arterial phase versus 0.525 in the portal phase.

Estimating kidney function in HIV-infected adults in Kenya: comparison to a direct measure of glomerular filtration rate by iohexol clearance

Background

More than two-thirds of the world's HIV-positive individuals live in sub-Saharan Africa, where genetic susceptibility to kidney disease is high and resources for kidney disease screening and antiretroviral therapy (ART) toxicity monitoring are limited. Equations to estimate glomerular filtration rate (GFR) from serum creatinine were derived in Western populations and may be less accurate in this population.

Methods

We compared results from published GFR estimating equations with a direct measure of GFR by iohexol clearance in 99 HIV-infected, ART-naïve Kenyan adults. Iohexol concentration was measured from dried blood spots on filter paper. The bias ratio (mean of the ratio of estimated to measured GFR) and accuracy (percentage of estimates within 30% of the measured GFR) were calculated.

Results

The median age was 35 years, and 60% were women. The majority had asymptomatic HIV, with median CD4+ cell count of 355 cells/mm³. Median measured GFR was 115 mL/min/1.73 m². Overall accuracy was highest for the Chronic Kidney Disease Epidemiology Consortium (CKD-EPI) equation. Consistent with a prior report, bias and accuracy were improved by eliminating the coefficient for black race (85% of estimates within 30% of measured GFR). Accuracy of all equations was poor in participants with GFR 60–90 mL/min/1.73 m² (<65% of estimates within 30% of measured GFR), although this subgroup was too small to reach definitive conclusions.

Conclusions

Overall accuracy was highest for the CKD-EPI equation. Eliminating the coefficient for race further improved performance. Future studies are needed to determine the most accurate GFR estimate for use in individuals with GFR <90 mL/min/1.73 m², in whom accurate estimation of kidney function is important to guide drug dosing. Direct measurement of GFR by iohexol clearance using a filter paper based assay is feasible for research purposes in resource-limited settings, and could be used to develop more accurate GFR estimates in African populations.

Perfusion CT vascular parameters do not correlate with immunohistochemically derived microvessel density count in colorectal tumors

PURPOSE

To determine whether perfusion computed tomography (CT)-derived vascular parameters-namely, blood flow, mean transit time (MTT), volume transfer constant (K(trans)), permeability-surface area product (PS), extracellular extravascular space volume, and vascular volume-correlate with the immunohistologic markers of angiogenesis in colorectal tumors.

MATERIALS AND METHODS

This prospective study was approved by the Regional Ethics and Research and Development Committees. The perfusion CT protocol was incorporated in the staging CT after informed consent in 29 patients (14 men, 15 women; mean age, 70 years; age range, 55-94 years). The perfusion parameters were calculated over two regions of interest (ROIs), at the invasive and luminal site defined by two radiologists independently. Accurate representative data were captured manually by correcting for motion artifacts and were analyzed by using Matlab software. The vascular heterogeneity between ROIs was assessed by using the Wilcoxon signed rank test. Perfusion CT parameters were correlated with the microvessel density (MVD) count at both corresponding sites obtained by means of immunohistochemical staining of the selected histologic slide with factor VIII and CD105 antigens by using Spearmen rank coefficient.

RESULTS

There was no statistically significant difference found between perfusion CT vascular parameters at the two ROIs by either of the radiologists. The Pearson coefficient for blood flow, MTT, K(trans), and PS at the two ROIs demonstrated good to moderate interobserver variability (for the two ROIs, 0.46 and 0.44; 0.67 and 0.64; 0.41 and 0.72; and 0.86 and 0.56, respectively). None of these parameters correlated with MVD count at the invasive or the luminal site for either of the two antigens.

CONCLUSION

Perfusion CT measurements may measure vascularity of colorectal tumors, however, correlation with MVD, which is a morphologic measure, appears inappropriate. © RSNA, 2013.

Volumetric low-tube-voltage CT imaging for evaluating hypervascular hepatocellular carcinoma; effects on radiation exposure, image quality, and diagnostic performance

OBJECTIVES

To assess the value of hepatic arterial-phase (HAP) imaging with a low tube voltage (80 kVp), using non-helical, volumetric acquisition with a 320-detector-rows area-detector CT (ADCT) scanner for evaluating hypervascular hepatocellular carcinoma (HCC) compared with routine 120-kVp HAP imaging.

METHODS

This study enrolled 128 patients with 148 HCCs. Seventy-six patients with 79 HCCs underwent HAP imaging with 80 kVp obtained using a 320-detector-rows ADCT scanner. The remaining 52 patients with 69 HCCs underwent routine HAP imaging with 120 kVp obtained by 64-slice helical acquisition. Image noise and tumor to liver contrast-to-noise ratio (CNR) of the two sets of images were compared. Three radiologists evaluated both sets of images using receiver operating characteristic analyses.

RESULTS

Although there was a two-fold increase in the mean image noise with 80 kVp over that with 120 kVp (p < 0.001), no significant differences were observed in CNR among the two sets. The mean area under the curve (Az value) and the sensitivity for detecting HCC with 80 kVp (0.980, 78/79, respectively) were higher than that of 120 kVp (0.892, 55/69, respectively).

CONCLUSIONS

HAP imaging with 80 kVp obtained by an ADCT scanner significantly improves the diagnostic performance for evaluating hypervascular HCC.

Pediatric thoracic paravertebral block: roentgenologic evidence for extensive dermatomal coverage

A case of a 10 year old boy who underwent a T10 continuous thoracic paravertebral block (TPVB) using a standard technique for postoperative pain management is reported. In the postoperative recovery area, 10 mL of Omnipaque contrast dye was injected through the catheter and an anteroposterior chest radiograph was performed. The radiograph showed longitudinal spread of contrast parallel to the spine from the T(4)-T(5) intervertebral disc to the T(10)-T(11) intervertebral disc with clear lateral extension of contrast along the fifth through the tenth intercostal nerves.

Comparison of computed tomography- and optical image-based assessment of liposome distribution

The use of multimodal imaging as a tool to assess the in vivo pharmacokinetics and biodistribution of nanocarriers is important in understanding the nature of their in vivo transport. The current study reports the development of a nano-sized liposomal computed tomographic (CT)/optical imaging probe carrying iohexol and Cy5.5 and its use in micro-CT and optical imaging to quantitatively assess the whole-body (macroscopic), intratumoral, and microscopic distribution over a period of 8 days. These multimodal liposomes have a vascular half-life of 30.3 ± 8.9 hours in mice bearing subcutaneous H520 non-small cell lung cancer tumors, with the maximum liposome accumulation in tumor achieved 48 hours postinjection. The in vivo liposome distribution and stability were quantitatively assessed using both micro-CT and fluorescence molecular tomography. The combination of CT and optical imaging enables visualization of the liposomes at the whole-body, tumor, and cellular scales with high sensitivity. Such noninvasive tracking of therapeutic vehicles at the macro- and microscale is important for informed and rational development of novel nanocarrier systems.

Renal cell carcinoma metastases to the pancreas: value of arterial phase imaging at MDCT

BACKGROUND

The pancreas is an increasingly recognized site of renal cell carcinoma metastases. It is important to determine the optimal MDCT protocol to best detect RCC metastases to the pancreas.

PURPOSE

To compare the rate of detection of renal cell carcinoma metastases to the pancreas between arterial and portal venous phase MDCT.

MATERIAL AND METHODS

A retrospective review of CTs of the abdomen yielded six patients with metastatic RCC to the pancreas. Five of six patients had pathologically proven clear cell RCC. Two blinded reviewers independently reported the number of pancreatic lesions seen in arterial and venous phases. Each lesion was graded as definite or possible. The number of lesions was determined by consensus review of both phases. Attenuation values were obtained for metastatic lesions and adjacent normal pancreas in both phases.

RESULTS

There were a total of 24 metastatic lesions to the pancreas. Reviewer 1 identified 20/24 (83.3%) lesions on the arterial phase images and 13/24 (54.2%) lesions on the venous phase. Seventeen of 20 (85.0%) arterial lesions were deemed definite and 9/13 (69.2%) venous lesions were definite. Reviewer 2 identified 19/24 (79.2%) lesions on the arterial phase and 14/24 (58.3%) on the venous phase. Seventeen of 19 (89.5%) arterial lesions were definite and 7/14 (50%) venous lesions were definite. Mean attenuation differential between lesion and pancreas was 114 HU and 39 HU for arterial and venous phases, respectively (P<0.0001).

CONCLUSION

Detection of RCC metastases to the pancreas at MDCT is improved using arterial phase imaging compared to portal venous phase imaging.

Spontaneous urinary extravasation: detection rate with 64-row multidetector computed tomography in patients presenting with acute abdomen

The aim of this study was to detect the rate of spontaneous urinary extravasation (SUE) with computed tomography (CT) in patients presenting with acute abdomen. Seven hundred thirteen abdominal CT examinations with i.v. contrast media requested mainly from the emergency department and urology clinics for sudden onset abdominal pain, flank pain, nonspecific abdominal pain with nausea and vomiting, and renal colic between September 2007 and August 2011 were retrospectively reviewed. Only adult patients were included in the study. Three patients with SUE were detected. One had a mid-ureteral stone while the etiology for the other two patients was unknown. Two of the patients were treated conservatively; one was treated with stenting with a double-j catheter. SUE should be considered in the differential diagnosis of patients presenting with acute abdomen and perinephric-periureteral fluid collection inconsistent with stone size and who are occasionally stone free. Early and precise diagnosis of SUE plays an important role in the management protocol of patients presenting with acute abdomen.

Dysphagia and an abnormal esophagram: a case report

This case report details the history, diagnostic workup, and follow-up of an 82-year-old dysphagic African-American woman who presented for an esophagram/barium swallow study. Radiologic and endoscopic imaging results and findings are discussed. In addition, the patient's treatment regimen and follow-up care are presented to better educate the radiologic technology community.

Comparison of double contrast-enhanced ultrasound and MDCT for assessing vascular involvement of pancreatic adenocarcinoma: preliminary results correlated with surgical findings

PURPOSE

To investigate the accuracy of double contrast-enhanced ultrasound (DCEUS) for assessing vascular involvement by pancreatic adenocarcinoma.

MATERIALS AND METHODS

38 patients with pancreatic adenocarcinoma proven by postoperative pathology or biopsy were enrolled in this study. DCEUS (intravenous microbubbles combined with an oral contrast agent) and 16-row multi-detector CT (MDCT) were performed preoperatively to assess vascular invasion by pancreatic adenocarcinoma. The diagnostic accuracy of DCEUS and MDCT for assessing vascular involvement was calculated and compared. ROC curves were used to evaluate the diagnostic confidences of the two methods. The inter- and intra-observer reliability of DCEUS for assessing vascular invasion was investigated in the present study.

RESULTS

Almost perfect agreement between DCEUS and MDCT was obtained using Kappa analysis (k = 0.83, p = 0.000). Compared with surgical findings, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of peripancreatic vascular invasion were 66.67 %, 100 %, 100 %, 60 %, and 77.78 %, respectively, for DCEUS and 75 %, 100 %, 100 %, 66.67 %, and 83.33 %, respectively, for MDCT. There was no significant difference in accuracy between DCEUS and MDCT for evaluating peripancreatic vascular invasion (p = 0.108). The combination of DCEUS and MDCT increased the diagnostic confidence in assessing peripancreatic vascular invasion with an area under ROC curve from 0.83 for DCEUS (p = 0.025) and 0.88 for MDCT (p = 0.011) to 0.92 for both combined (p = 0.005). The intra- and inter-observer reproducibility were both almost perfect for assessing the peripancreatic vascular invasion by DCEUS with a Kappa value of 0.94 (p = 0.000) for intra-observer and 0.83 (p = 0.000) for inter-observer.

CONCLUSION

DCEUS could be considered as a reliable and accurate method for evaluating the peripancreatic vascular invasion of pancreatic adenocarcinoma.

Perfusion CT to assess angiogenesis in colon cancer: technical limitations and practical challenges

OBJECTIVE

Perfusion CT may have the potential to quantify the degree of angiogenesis of solid tumours in vivo. This study aims to identify the practical and technical challenges inherent to the technique, and evaluate its feasibility in colorectal tumours.

METHODS

51 patients from 2 institutions prospectively underwent a single perfusion CT on 2 different multidetector scanners. The patients were advised to breath-hold as long as possible, followed by shallow breathing, and were given intravenous buscopan to reduce movement. Numerous steps were explored to identify the challenges.

RESULTS

43 patients successfully completed the perfusion CT as per protocol. Inability to detect the tumour (n=3), misplacement of dynamic sequence co-ordinates (n=2), failure of contrast injection (n=2) and displacement of tumour (n=1) were the reasons for failure. In 14 cases excessive respiratory motion displaced the tumour out of the scanning field along the temporal sequence, leading to erroneous data capture. In nine patients, minor displacements of the tumour were corrected by repositioning the region of interest (ROI) to its original position after reviewing each dynamic sequence slice. In 20 patients the tumour was stable, and data captured from the ROI were representative, and could have been analysed by commercially available Body Tumor Perfusion 3.0® software (GE Healthcare, Waukesha, WI). Hence all data were manually analysed by MATLAB® processing software (MathWorks, Cambridge, UK).

CONCLUSION

Perfusion CT in tumours susceptible to motion during acquisition makes accurate data capture challenging and requires meticulous attention to detail. Motion correction software is essential if perfusion CT is to be used routinely in colorectal cancer.

Temporary targeted renal blood flow interruption using a reverse thermosensitive polymer to facilitate bloodless partial nephrectomy: a swine survival study

What's known on the subject? and What does the study add? Lumagel™ is a reverse thermosensitive polymer (RTP) that has previously been described in the literature as providing temporary vascular occlusion to allow for bloodless partial nephrectomy (PN) while maintaining blood flow to the untargeted portion of the kidney. At body temperature, Lumagel™ has the consistency of a viscous gel but upon cooling rapidly converts to a liquid state and does not reconstitute thereafter. This property has allowed for it to be used in situations requiring temporary vascular occlusion. Previous experience with similar RTPs in coronary arteries proved successful, with no detectable adverse events. We have previously described our technique for temporary vascular occlusion of the main renal artery, as well as segmental and sub-segmental renal branches, to allow for bloodless PN in either an open or minimally invasive approach. These experiments were performed in the acute setting. This study is a two-armed survival trial to assess whether this RTP is as safe as hilar clamping for bloodless PN. Surviving animals showed normal growth after using the RTP, absence of toxicity, no organ dysfunction, and no pathological changes attributable to the RTP. We conclude that Lumagel™ is as safe as conventional PN with hilar clamping, while adding the advantage of uninterrupted perfusion during renal resection.

OBJECTIVE

To examine whether randomly selected regions of the kidney could undergo temporary flow interruption with a reverse thermosensitive polymer (RTP), Lumagel™ (Pluromed, Inc., Woburn, MA, USA), followed by partial nephrectomy (PN), without adding risks beyond those encountered in the same procedure with the use of hilar clamping.

MATERIALS AND METHODS

A two-armed (RTP vs hilar clamp), 6-week swine survival study was performed. Four swine underwent PN using hilar clamps, while six underwent PN with flow interruption using the RTP. The RTP, administered angiographically, was used for intraluminal occlusion of segmental or subsegmental arteries and was compared with main renal artery clamping with hilar clamps. The resection site was randomized for each swine. Laboratory studies were performed preoperatively, and at weeks 1, 3 and 6. Before killing the swine, repeat angiography was performed with emphasis on the site of previous flow interruption. Gross and microscopic examination of kidney, liver, lung, heart, skeletal muscle was later performed, and the vessel that had supported the previous plug was examined.

RESULTS

All animals survived. No abnormal chemistry or haematology results were encountered over the 6 weeks. There were no surgical complications in either group. Using angiography we found 100% patency of vessels that had been occluded with the polymer 6 weeks previously for PN. The only gross or microscopic abnormalities were related to the renal resection and scar formation, and were similar in the two groups.

CONCLUSION

Targeted flow interruption with the RTP added no additional risk to PN while allowing bloodless resection and uninterrupted flow to untargeted renal tissue.

Assessment of myocardial viability using multidetector computed tomography in patients with reperfused acute myocardial infarction

AIM

To assess the prognostic value of 64-section multidetector computed tomography (MDCT) to predict follow-up myocardial dysfunction and functional recovery after reperfusion therapy in patients with acute myocardial infarction (MI) as defined by echocardiography.

MATERIALS AND METHODS

After reperfusion therapy for acute MI, 71 patients underwent two-phase contrast-enhanced MDCT and follow-up echocardiography. MDCT findings were compared with echocardiographic findings using kappa statistics. The areas under the receiver operating characteristic curves (AUCs) and the odds ratios (ORs) of early perfusion defects (EPD), delayed enhancement (DE), and residual perfusion defects (RPD) for predicting follow-up myocardial dysfunction and functional recovery were calculated on a segmental basis.

RESULTS

The presence of transmural EPD (EPD(TM)) or RPD showed good agreement (k = 0.611 and 0.658, respectively) with follow-up myocardial dysfunction, while subendocardial EPD (EPD(sub)) or subendocardial DE (DE(sub)) showed fair agreement with follow-up myocardial dysfunction (k = 0.235 and 0.234, respectively). The AUC of RPD (0.796) was superior (p < 0.001 and 0.031, respectively) to those of EPD(TM) (0.761) and DE(TM) (0.771). The presence of EPD(TM), DE(TM), and RPD were significant, independent positive predictors of follow-up myocardial dysfunction (OR = 6.4, 1.9, and 9.8, respectively). EPD(TM) was a significant, independent negative predictor of myocardial functional recovery (OR = 0.13).

CONCLUSION

Abnormal myocardial attenuation on two-phase MDCT after reperfusion therapy may provide promising information regarding myocardial viability in patients with acute MI.

Diagnostic value of the post-processing technique of multi-slice spiral CT in orbital cyst diseases

PURPOSE

To analyze the features of CT imaging of orbital cystic disease.

METHODS

A total of 30 patients were pathologically confirmed with orbital cystic disease between January 2007 and March 2012. Prior to operation, the participants underwent CT scans with image processing by maximum intensity projection (MIP) and volume rendering (VR). Preoperative CT diagnostic outcomes were compared with postoperative pathological findings.

RESULTS

The patients presented with round, oval and dumbbell shaped masses. Fourteen cases of dermoid cyst and 8 cases of epidermoid cyst showed heterogeneous density. Among the dermoid cyst patients, 6 cases had demixing phenomenon, 3 cases had lipid drift and 5 cases showed mild or moderate intensity enhancement in the cyst wall. No intensity enhancement was observed in the epidermoid cyst patients. Five cases had high intensity due to hemorrhage and 3 patients presented with adjacent sclerotin arc compression; 5 cases of myxoid cyst had homogenous density and no intensity enhancement was found when iohexol was injected. Three patients with atheromatous cyst had heterogeneous density, with CT value ranging from -36Hu to 191Hu. Floss was noted centrally in 1 case and mild to moderate intensity enhancement was observed in the cyst wall with iohexol injection.

CONCLUSION

Multi-slice CT is useful in the diagnosis of orbital cystic disease. Multi-slice CT combined with image processing can be helpful in displaying the location and size of masses, and revealing the relationship between masses and surrounding boney tissue, providing an objective basis for surgical planning when combined with 3D-CT imaging.