Value of single-dose contrast-enhanced magnetic resonance angiography versus intraarterial digital subtraction angiography in therapy indications in abdominal and iliac arteries

The objective of the study was to prove the value of single-dose contrast-enhanced magnetic resonance angiography [three-dimensional (3D) ceMRA] in abdominal and iliac arteries versus the reference standard intra-arterial digital subtraction angiography (i.a.DSA) when indicating a therapy. Patients suspected of having abdominal or iliac artery stenosis were included in this study. A positive vote of the local Ethics Committe was given. After written informed consent was obtained, 37 patients were enrolled, of which 34 were available for image evaluation. Both 3D ceMRA and i.a. DSA were performed for each patient. The dosage for 3D ceMRA was 0.1 mmol/kg body weight in a 1.5-T scanner with a phased-array coil. The parameters of the 3D-FLASH sequence were as follows: TR/TE 4.6/1.8 ms, effective thickness 3.5 mm, matrix 512 x 200, flip angle 30 degrees , field of view 420 mm, TA 23 s, coronal scan orientation. Totally, 476 vessel segments were evaluated for stenosis degree by two radiologists in a consensus fashion in a blinded read. For each patient, a therapy was proposed, if clinically indicated. Sensitivity, specificity, positive and negative predictive values, and accuracy for stenoses > or = 50% were 68%, 92%, 44%, 97%, and 90%, respectively. In 13/34 patients, a discrepancy was found concerning therapy decisions based on MRA findings versus therapy decisions based on the reference standard DSA. The results showed that the used MRA imaging technique of abdominal and iliac arteries is not competitive to i.a. DSA, with a high rate of misinterpretation of the MRAs resulting in incorrect therapies.

Initial clinical experience with contrast-enhanced digital breast tomosynthesis

RATIONALE AND OBJECTIVES

Contrast-enhanced digital mammography and digital breast tomosynthesis are two imaging techniques that attempt to increase malignant breast lesion conspicuity. The combination of these into a single technique, contrast-enhanced digital breast tomosynthesis (CE-DBT), could potentially integrate the strengths of both. The objectives of this study were to assess the clinical feasibility of CE-DBT as an adjunct to digital mammography, and to correlate lesion enhancement characteristics and morphology obtained with CE-DBT to digital mammography, ultrasound, and magnetic resonance (MR).

MATERIALS AND METHODS

CE-DBT (GE Senographe 2000D; Milwaukee, WI) was performed as a pilot study in an ongoing National Cancer Institute-funded grant (P01-CA85484) studying multimodality breast imaging. Thirteen patients with ACR BI-RADS category 4 or 5 breast lesions underwent imaging with digital mammography, ultrasound, MR, and CE-DBT. CE-DBT was performed at 49 kVp with a rhodium target and a 0.27-mm copper (Alfa Aesar, Ward Hill, MA) filter. Preinjection and postinjection DBT image sets were acquired in the medial lateral oblique projection with slight compression. Each image set consists of nine images acquired over a 50-degree arc and was obtained with a mean glandular x-ray dose comparable to two conventional mammographic views. Between the precontrast and postcontrast DBT image sets, a single bolus of iodinated contrast agent (1 ml/kg at 2 ml/s, Omnipaque-300; Amersham Health Inc., Princeton, NJ) was administered. Images were reconstructed using filtered-backprojection in 1-mm increments and transmitted to a clinical PACS workstation.

RESULTS

Initial experience suggests that CE-DBT provides morphologic and vascular characteristics of breast lesions qualitatively concordant with that of digital mammography and MR.

CONCLUSION

As an adjunct to digital mammography, CE-DBT may be a potential alternative tool for breast lesion morphologic and vascular characterization.

Serum neutrophil gelatinase-associated lipocalin as a marker of renal function in children with chronic kidney disease

Very few biomarkers exist for monitoring chronic kidney disease (CKD). We have recently shown that serum neutrophil gelatinase-associated lipocalin (NGAL) represents a novel biomarker for early identification of acute kidney injury. In this study, we hypothesized that serum NGAL may also represent a biomarker for the quantitation of CKD. Forty-five children with CKD stages 2-4 were prospectively recruited for measurement of serum NGAL, serum cystatin C, glomerular filtration rate (GFR) by Ioversol clearance, and estimated GFR (eGFR) by Schwartz formula. Serum NGAL significantly correlated with cystatin C (r=0.74, P<0.000). Both NGAL and cystatin C significantly correlated with measured GFR (r=0.62, P<0.000; and r=0.71, P<0.000, respectively) as well as with eGFR (r=0.66, P<0.000 and r=0.59, P<0.000, respectively). At GFR levels of >or=30 ml/min per 1.73 m(2), serum NGAL, cystatin C, and eGFR were all significantly correlated with measured GFR. However, in subjects with lower GFRs (<30 ml/min per 1.73 m(2)), serum NGAL levels correlated best with measured GFR (r=0.62), followed by cystatin C (r=0.41). We conclude that (a) both serum NGAL and cystatin C may prove useful in the quantitation of CKD, and (b) by correlation analysis, NGAL outperforms cystatin C and eGFR at lower levels of measured GFR.

In-vivo flow simulation in coronary arteries based on computed tomography datasets: feasibility and initial results

The purpose of this paper was to non-invasively assess hemodynamic parameters such as mass flow, wall shear stress (WSS), and wall pressure with computational fluid dynamics (CFD) in coronary arteries using patient-specific data from computed tomography (CT) angiography. Five patients (two without atherosclerosis, three with atherosclerosis) underwent retrospectively electrocardiogram (ECG) gated 16-detector row CT using ECG-pulsing and geometric models of coronary arteries were reconstructed for CFD analysis. Blood flow was considered laminar, incompressible, Newtonian, and pulsatile. The mass flow, WSS, and wall pressure were quantified and flow patterns were visualized. The wall pressure continuously decreased towards distal segments and showed pressure drops in stenotic segments. In coronary segments without atherosclerotic wall changes, WSS remained low, even during phases of high flow velocity, whereas in atherosclerotic vessels, the WSS was elevated already at low flow velocities. Stenoses and post-stenotic dilatations led to flow acceleration and rapid deceleration, respectively, including a distortion of flow. Areas of high WSS and high flow velocities were found adjacent to plaques, with values correlating with the degree of stenosis. CFD provided detailed mass flow measurements. CFD analysis is feasible in normal and atherosclerotic coronary arteries and provides the rationale for further investigation of the links between hemodynamic parameters and the significance of coronary stenoses.

Multislice computed tomography coronary angiography at a local hospital: Pitfalls and potential

PURPOSE

To evaluate whether the favorable results achieved with multislice computed tomography (MSCT) of coronary arteries at larger centers could be paralleled at a local hospital.

MATERIAL AND METHODS

Fifty consecutive patients with suspected coronary artery disease scheduled for invasive investigation with quantitative coronary angiography (QCA) at a university hospital underwent MSCT with a 16-slice scanner at a local hospital. Diagnostic accuracy of MSCT for coronary artery disease was assessed using a 16-segment coronary artery model with QCA as the gold standard.

RESULTS

Segments with diameter <2 mm, as defined by QCA, segments distal to occlusions, and stented segments were excluded. Of the remaining 489 segments, 73 (15%) were not assessable with MSCT. Sensitivity, specificity, and positive and negative predictive values for significant (>50%) stenosis for the 416 assessable segments were 92%, 82%, 53%, and 98%, respectively.

CONCLUSION

Our beginners' experience demonstrated favorable results regarding sensitivity and negative predictive value. The positive predictive value, however, was unsatisfactory. Calcifications were identified as the most important factor for false-positive results with MSCT. With widespread use of MSCT coronary angiography, there is a risk of recruiting patients without significant coronary artery disease to unnecessary and potentially harmful invasive procedures.

Risk factors of postoperative nephropathy in patients undergoing innovative CABG and intraoperative graft angiography

INTRODUCTION

Intraoperative graft angiography is considered gold standard in quality control of innovative CABG techniques. Iodixanol, an iso-osmolar, non-ionic contrast agent has been safely applied in patients with impaired renal function. We aimed to quantify postoperative nephropathy in CABG patients undergoing intraoperative angiography and to define associated risk factors.

METHODS

One hundred and thirty-five patients, aged 61 years (range: 43-83), underwent intraoperative angiography following CABG (36 robotically assisted CABG via sternotomy, 41 OPCAB and MIDCAB, 51 AHTECAB, 7 BHTECAB). In all patients iodixanol (Visipaque) was used, median amount: 150 ml (range: 20-500). Nephropathy was defined as an increase in serum creatinine concentration >or= 0.5 mg/dl compared with preoperative values.

RESULTS

Nephropathy occured in 19/135 (14%) patients, and was correlated with the following variables: preoperative serum creatinine (p = 0.015, r = 0.208), age (p = 0.008, r = 0.229), postoperative peak troponin T levels (p < 0.001, r = 0.545), postoperative CK-MB peak levels (p = 0.028, r = 0.189), and presence of peripheral vascular disease (p = 0.011). No correlation was found for the contrast agent amount, diabetes mellitus, hypertension, preoperative urea level, cardiopulmonary bypass time, aortic cross clamp time, postoperative CK peak levels. Multivariate analysis showed that postoperative peak troponin T levels (p < 0.001), preoperative serum creatinine (p = 0.031), and patient age (p = 0.043) were independently associated with a postoperative increase of serum creatinine. In all 19 patients with postoperative nephropathy serum creatinine levels returned to preoperative levels.

CONCLUSION

Patients with older age and elevated serum creatinine levels undergoing innovative CABG and intraoperative angiography were at increased risk of postoperative nephropathy. However, no correlation was found between the amount of contrast agent (iodixanol) applied and the nephropathy rate and none of the nephropathy cases persisted.

Iso-osmolar contrast medium better preserves short- and long-term renal function after cardiovascular catheterizations in patients with severe baseline renal insufficiency

BACKGROUND

Iso-osmolar iodixanol was shown to least affect very-short-term renal function. However, its short- and long-term renal effects after cardiovascular catheterizations in severe renal insufficiency remain unknown.

METHODS

Patients undergoing elective cardiovascular catheterizations and having pre-procedural serum creatinine (Scr) > or =2.5 mg/dl were prospectively studied. The results were compared to those of historical controls who received iopromide.

RESULTS

The iodixanol group included 27 patients, aged 73+/-1 years, and the case-matched control group consisted of another 27 patients, aged 71+/-1 years. The baseline Scr were 3.0+/-0.3 and 3.0+/-0.2 mg/dl respectively. Although the Scr at 3 months was similar, the Scr at 6 months was lower in the iodixanol group (2.7+/-0.3 vs 4.2+/-0.5 mg/dl, p = 0.017). The absolute and percentage increments in Scr at 3 months (0.0+/-0.2 vs 0.6+/-0.2 mg/dl, p = 0.014, and 1+/-4% vs 24+/-6%, p = 0.003, respectively) and 6 months (-0.3+/-0.2 vs 1.3+/-0.4 mg/dl, p = 0.001, and -10+/-5% vs 47+/-12%, p < 0.001, respectively) were lower in the iodixanol group.

CONCLUSIONS

Iodixanol better preserves short- and long-term renal outcomes in patients with severe baseline renal insufficiency.

Quadricuspid Aortic Valve

Cardiac multidetector helical computed tomography angiogram (MDCTA) findings of a quadricuspid aortic valve are presented. MDCTA enabled evaluation of the aortic valve and its function, the coronary arteries, and left ventricular function. This case is, to our knowledge, the first description of the MDCTA imaging appearance of quadricuspid aortic valve.

Multidetector computed tomography myocardial perfusion imaging during adenosine stress

OBJECTIVES

The purpose of this study is to validate the accuracy of multidetector computed tomography (MDCT) to measure differences in regional myocardial perfusion during adenosine stress in a canine model of left anterior descending (LAD) artery stenosis, during first-pass, contrast-enhanced helical MDCT.

BACKGROUND

Myocardial perfusion imaging by MDCT may have significant implications in the diagnosis and treatment of coronary artery disease.

METHODS

Eight dogs were prepared with a LAD stenosis, and contrast-enhanced MDCT imaging was performed 5 min into adenosine infusion (0.14 to 0.21 mg/kg/min). Images were analyzed using a semiautomated approach to define the regional signal density (SD) ratio (myocardial SD/left ventricular blood pool SD) in stenosed and remote territories, and then compared with microsphere myocardial blood flow (MBF) measurements.

RESULTS

Mean MBF in stenosed versus remote territories was 1.37 +/- 0.46 ml/g/min and 1.29 +/- 0.48 ml/g/min at baseline (p = NS) and 2.54 +/- 0.93 ml/g/min and 8.94 +/- 5.74 ml/g/min during adenosine infusion, respectively (p < 0.05). Myocardial SD was 92.3 +/- 39.5 HU in stenosed versus 180.4 +/- 41.9 HU in remote territories (p < 0.001). There was a significant linear association of the SD ratio with MBF in the stenosed territory (R = 0.98, p = 0.001) and between regional myocardial SD ratio and MBF <8 ml/g/min, slope = 0.035, SE = 0.007, p < 0.0001. Overall, there was a significant non-linear relationship over the range of flows studied (LR chi-square [2 degrees of freedom] = 31.8, p < 0.0001).

CONCLUSIONS

Adenosine-augmented MDCT myocardial perfusion imaging provides semiquantitative measurements of myocardial perfusion during first-pass MDCT imaging in a canine model of LAD stenosis.

Multifocal coronary artery myocardial bridging involving the right coronary and left anterior descending arteries detected by ECG-gated 64 slice multidetector CT coronary angiography

Myocardial bridging is a congenital condition in which a segment of a major epicardial coronary artery has an intramyocardial course. Myocardial bridging is usually confined to a single vessel (typically the mid segment of the left anterior descending artery) and is usually asymptomatic, however, bridging may be associated with chest pain, myocardial infarction, or sudden cardiac death. While more commonly identified at autopsy, myocardial bridging is occasionally diagnosed by coronary angiography with identification of concomitant myocardial bridging involving both the left and right coronary arteries appearing to be uncommon. We present three patients presenting with atypical chest pain symptoms in whom concomitant right coronary artery and left anterior descending artery myocardial bridging was identified by ECG gated multidetector computed tomography (MDCT).

Multi-slice CT angiography for arterial evaluation in the injured lower extremity

BACKGROUND

With the evolution of multi-slice helical computed tomographic angiography (MCTA), the optimal imaging modality for arterial injury in the traumatized lower extremity has been challenged. The objective of this study was to evaluate the ability of MCTA to detect arterial injury in the traumatized lower extremity. Our hypothesis was that MCTA is a sensitive and specific test for the non-invasive evaluation of lower extremity arterial injury.

METHODS

After Institutional Review Board approval, we reviewed all patients at our Level I trauma center who sustained lower extremity trauma and underwent initial evaluation by MCTA over a 3-year period ending in February 2005. MCTA accuracy was tested against a gold standard of operative intervention, duplex ultrasonography, catheter-based angiography, or clinical follow-up.

RESULTS

Sixty-three MCTAs were performed in 59 patients. MCTA was diagnostic in 62 of the 63 scans (98.4%). The mechanism was penetrating in 45.8%. Lower extremity fractures were present in 38.7% of patients studied. There were 22 positive studies. Out of this group, 19 were confirmed at operation and 3 were managed non-operatively. In the 19 injuries confirmed in the operating theater, there were 5 superficial femoral, 2 profunda, 10 popliteal, 1 posterior tibial, and 1 injury to all 3 mid-calf arteries. There were two injuries below the trifurcation managed non-operatively and there was one popliteal occlusion with distal reconstitution that was confirmed by duplex and managed non-operatively because of patient refusal of surgery. Forty studies were negative for arterial injury, with clinical follow up available in 89.5%, for a mean of 48.2 days (range, 5-287 days). No missed injuries were identified during the follow-up period. MCTA was non-diagnostic in 1 patient (1.6%), secondary to artifact from retained missile fragments. MCTA achieved 100% sensitivity and 100% specificity in detecting clinically significant arterial injury.

CONCLUSION

MCTA is a sensitive and specific non-invasive imaging modality for arterial evaluation in the injured lower extremity that may replace catheter-based angiography in most patients.

Association between hepatitis C virus and very-low-density lipoprotein (VLDL)/LDL analyzed in iodixanol density gradients

Hepatitis C virus (HCV) RNA circulates in the blood of persistently infected patients in lipoviroparticles (LVPs), which are heterogeneous in density and associated with host lipoproteins and antibodies. The variability and lability of these virus-host complexes on fractionation has hindered our understanding of the structure of LVP and determination of the physicochemical properties of the HCV virion. In this study, HCV from an antibody-negative immunodeficient patient was analyzed using three fractionation techniques, NaBr gradients, isotonic iodixanol, and sucrose gradient centrifugation. Iodixanol gradients were shown to best preserve host lipoprotein-virus complexes, and all HCV RNA was found at densities below 1.13 g/ml, with the majority at low density, < or =1.08 g/ml. Immunoprecipitation with polyclonal antibodies against human ApoB and ApoE precipitated 91.8% and 95.0% of HCV with low density, respectively, suggesting that host lipoprotein is closely associated with HCV in a particle resembling VLDL. Immunoprecipitation with antibodies against glycoprotein E2 precipitated 25% of HCV with low density, providing evidence for the presence of E2 in LVPs. Treatment of serum with 0.5% deoxycholic acid in the absence of salt produced HCV with a density of 1.12 g/ml and a sedimentation coefficient of 215S. The diameters of these particles were calculated as 54 nm. Treatment of serum with 0.18% NP-40 produced HCV with a density of 1.18 g/ml, a sedimentation coefficient of 180S, and a diameter of 42 nm. Immunoprecipitation analysis showed that ApoB remained associated with HCV after treatment of serum with deoxycholic acid or NP-40, whereas ApoE was removed from HCV with these detergents.

Coronary 64-slice computed tomographic angiography models employing aortic root and selective catheter directed contrast enhancement in swine: technical feasibility and preliminary results using 3D and 4D reconstructions

PURPOSE

The technical feasibility of combining catheter directed coronary enhancement and multidetector computed tomographic angiography (MD-CTA) is presented in a swine model at various cardiac and injection rates.

MATERIALS/METHODS

A 64-slice CT scanner was used under animal IRB approval in four sedated swine. Common femoral venous/arterial access with a 5 Fr micropuncture kit was ultrasound guided. Investigational 5 Fr diffusion-tip pigtail [aortic root (AR)-MD-CTA] and conventional 5 Fr coronary [selective (S)-MD-CTA] catheters were positioned on the CT table with c-arm fluoroscopy. AR-MD-CTA commenced 1-2 s after injection of 50 cc Visipaque mixed with 50 cc NS at 6 cc/s (n=3), 8 cc/s (n=5) or 10 cc/s (n=7) (HR=120, 100, 90, 80 or 65 bpm). S-MD-CTA (right and left, n=4) (HR= 90, 80, or 65 bpm) commenced 1-2 s after injection of 5 cc Visipaque mixed with 5 cc NS (1 cc/s). IV-MD-CTA (n=4) (HR=80 bpm) commenced 5 or 10 s after aortic peak density with 100 cc Visipaque (5 cc/s) and 50 or 75 cc NS (5 cc/s) flush. Conventional angiography (n=2) used standard protocol. MD-CTA was performed with the following parameters: collimation 0.6 mm, tube rotation time 0.3 s, table feed/rotation 3.8 mm, scan time 10-12 s, tube voltage 120 kVp, effective mAs 850, pitch 0.2, FOV 109-123 mm, slice thickness/increment 0.6 mm/0.3 mm, kernel B25 f smooth. Ex vivo imaging (64-slice CT, n=3) was also performed. Post-processing consisted of coronary peak densities, 3D-MIP's and 4D projections.

RESULTS

Catheter directed MD-CTA was feasible at all injection rates at and below 100 bpm and yielded higher peak coronary attenuation values than IV-enhanced studies. Definition and clarity of the tributary and distal anatomy was also higher than IV-enhanced CTA.

CONCLUSIONS

Catheter directed MD-CTA can be performed by retrofitting the current CT scanner with a portable c-arm fluoroscopy unit. S and AR MD-CTA provide high coronary anatomy definition and luminal attenuation without obscuring cardiac chamber signal and with the least iodinated contrast volume.

Evaluation of Cerebral Hemodynamics With Computed Tomography Perfusion Using Gadolinium as an Alternative to Iodinated Contrast

Computed tomography (CT) perfusion is traditionally performed using iodinated contrast, but this can be problematic in patients with impaired renal function or contrast allergy. We report a case of a 63-year-old man whose medical history was complicated by chronic renal failure, which was exacerbated after placement of a left cervical internal carotid artery stent by 70% stenosis and left hemisphere perfusion deficit. On a follow-up clinic visit, because of the patient s chronic renal failure, CT perfusion was performed successfully using gadolinium without further renal complications.

Contrast-enhanced multidetector computed tomography viability imaging after myocardial infarction: characterization of myocyte death, microvascular obstruction, and chronic scar

BACKGROUND

The ability to distinguish dysfunctional but viable myocardium from nonviable tissue has important prognostic implications after myocardial infarction. The purpose of this study was to validate the accuracy of contrast-enhanced multidetector computed tomography (MDCT) for quantifying myocardial necrosis, microvascular obstruction, and chronic scar after occlusion/reperfusion myocardial infarction.

METHODS AND RESULTS

Ten dogs and 7 pigs underwent balloon occlusion of the left anterior descending coronary artery (LAD) followed by reperfusion. Contrast-enhanced (Visipaque, 150 mL, 325 mg/mL) MDCT (0.5 mm x 32 slice) was performed before occlusion and 90 minutes (canine) or 8 weeks (porcine) after reperfusion. MDCT images were analyzed to define infarct size/extent and microvascular obstruction and compared with postmortem myocardial staining (triphenyltetrazolium chloride) and microsphere blood flow measurements. Acute and chronic infarcts by MDCT were characterized by hyperenhancement, whereas regions of microvascular obstruction were characterized by hypoenhancement. MDCT infarct volume compared well with triphenyltetrazolium chloride staining (acute infarcts 21.1+/-7.2% versus 20.4+/-7.4%, mean difference 0.7%; chronic infarcts 4.15+/-1.93% versus 4.92+/-2.06%, mean difference -0.76%) and accurately reflected morphology and the transmural extent of injury in all animals. Peak hyperenhancement of infarcted regions occurred approximately 5 minutes after contrast injection. MDCT-derived regions of microvascular obstruction were also identified accurately in acute studies and correlated with reduced flow regions as measured by microsphere blood flow.

CONCLUSIONS

The spatial extent of acute and healed myocardial infarction can be determined and quantified accurately with contrast-enhanced MDCT. This feature, combined with existing high-resolution MDCT coronary angiography, may have important implications for the comprehensive assessment of cardiovascular disease.

Staging of pancreatic cancer with multidetector CT in the setting of preoperative chemoradiation therapy

BACKGROUND

Preoperative chemoradiation can potentially improve outcomes in patients with pancreatic cancer. This study addresses its effect on staging pancreatic cancer with multidetector computed tomography (MDCT).

METHODS

Fifty-five patients underwent a dual-phase MDCT pancreas protocol for proved pancreatic cancer. Of these, 16 patients underwent preoperative chemoradiation. Three radiologists independently reviewed images to assess for locally advanced disease, liver and peritoneal metastases on baseline studies of all 55 patients, and on follow-up preoperative studies for the 16 patients receiving preoperative therapy. Overall score for resectability was graded on a scale from 1 to 5 (1, definitely resectable; 5. definitely unresectable). Receiver operating characteristic curves and weighted (kappa statistics were determined.

RESULTS

The areas under the receiver operating characteristic curves for readers 1, 2, and 3 were 0.98, 0.96, and 0.90, respectively. Weighted kappa values for reader 1 versus reader 2, reader 1 versus reader 3, and reader 2 versus reader 3 were 0.90, 0.57, and 0.54, respectively. Interpreting scores of 1 to 3 for resectability as resectable disease, the mean values for sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were 0.92, 0.91, 0.74, 0.98, and 0.92 respectively.

CONCLUSION

The negative predictive value for MDCT for identifying unresectable pancreatic cancer in the setting of preoperative therapy is comparable to that reported in the absence of neoadjuvant therapy.

Helical CT in the diagnosis of acute lower gastrointestinal haemorrhage

INTRODUCTION

A pilot study to evaluate helical computer tomography (CT) as a diagnostic tool for acute lower gastrointestinal tract (GIT) bleeding. CT was compared to conventional angiography (CA) and colonoscopy for the diagnosis and detection of bleeding site in suspected cases of acute lower GIT bleeding.

METHODS

Seven patients presenting with acute lower GIT bleeding, between June and November 2002, underwent CT examinations. All of these seven patients underwent CA following CT. Emergency colonoscopies were performed on five patients investigated with both CT and CA. Median delay from the most recent episode of hematochezia to CT was two and a half hours, to CA was 3h, and to colonoscopy was 4h. None of the patients underwent nuclear medicine (NM) bleeding studies.

RESULTS

Haemoglobin drop in all patients was greater than 15 g/L in the first 24h of presentation. The mean age was 68.86 years (range, 49-83 years). Comparing CT and CA, there were four concordant and three discordant results. Both modalities had concordant findings of two active bleeding sites, one non-bleeding rectal tumour, and one negative case result. In three patients, the source of bleeding was found on CT whereas CA was negative. Emergency colonoscopies performed in all of these three patients confirmed blood in the colon/ileum.

CONCLUSION

Early experience suggests that CT is a safe, convenient and accurate diagnostic tool for acute lower GIT haemorrhage. It raises questions regarding the sensitivity of CA. A new management algorithm for acute lower GIT haemorrhage using CT as the pre-CA screening tool is being proposed based on the preliminary findings. Positive CT will allow directed therapeutic angiography, while negative CT will triage patients into alternative management pathways.

Lung cancer detected in patients presenting to the Emergency Department studies for suspected pulmonary embolism on computed tomography pulmonary angiography

PURPOSE

To study the frequency and demographics of lung cancer on CT pulmonary angiography in patients with suspected pulmonary embolism referred from the Emergency Department.

MATERIALS AND METHODS

Retrospective review of the medical records and radiology reports, clinical and imaging follow-up studies and pathological reports revealed 1106 CT pulmonary angiography studies referred from our Emergency Department during the 15-month period between March 2003 and June 2004.

RESULTS

Five incidental lung cancer cases were found in 1106 studies from 1081 patients (0.47%). Pulmonary embolism was found in 95 patients (8.5%). Among the five incidental cases three patients were female and two were male (62-81 years old; mean 73 years, 17-130 packs year; mean 51 packs year). Tumor size ranged from 1.8 to 4.5 cm (mean 3.3 cm). The stagings of the lung cancers were IIIB in one patient and IV in four patients.

CONCLUSION

Previously undiagnosed lung cancer was detected in 0.45% of patients among 1081 patients referred from Emergency Department, one of whom had coexistent pulmonary embolism. All five patients presented at advanced lung cancer stages of IIIB and IV.

Relationship of the esophagus and aorta to the left atrium and pulmonary veins: Implications for catheter ablation of atrial fibrillation

BACKGROUND

A potential complication during ablation of atrial fibrillation (AF) is damage to adjacent structures such as the esophagus and aorta. Fatal atrio-esophageal fistulas have developed after surgery- or catheter-based AF ablation procedures.

OBJECTIVES

The purpose of this study was to analyze multidetector computed tomography (MDCT) angiographic images to determine the anatomic relationship of the aorta and esophagus to the left atrium (LA).

METHODS

Sixty-five subjects underwent CT imaging using a 16-slice MDCT scanner: 24 with paroxysmal AF, 21 with chronic AF, and 20 "control" subjects without a history of AF. Measurements assessed included LA diameters, width of the esophagus and aorta in contact with the posterior LA wall, and distance from the esophagus to the four pulmonary veins (PVs), spine, and LA endocardium.

RESULTS

Mean LA diameters were significantly larger in patients with AF vs the control group (P = .003 for anteroposterior diameter; P = .009 for transverse diameter). The anterior aspect of the esophagus was directly apposed to the LA in all cases (contact width 18.9 +/- 4.4 mm). The position of the esophagus varied in the posterior mediastinum but on average was closer to the ostia of the left PVs (P = .0001). The descending aorta was in contact with the LA and/or left PVs in 50 of 65 subjects. The esophagus was closer to the spine in the chronic AF vs control group (P = .007), likely due to increased LA dimension.

CONCLUSION

In addition to its ability to assess PV anatomy, preprocedural MDCT imaging can investigate the variable relationship of adjacent structures, such as the esophagus and aorta to the LA and PVs.

Chronic pseudoaneurysm of the left ventricle

We present a case of a 55-year-old men who suffered a silent myocardial infarction four years earlier and presented with exertional dyspnoea. Cardiac magnetic resonance imaging (CMR) and Multislice computed tomography (MSCT) was performed and revealed a giant pseudoaneursym of the lateral wall of the left ventricle with the presence of a thrombus in the lateral wall of the pseudoaneursym. We present this case since excellent non-invasive evaluation of the pseudoaneursym was feasible using state-of-the-art imaging modalities. Information on left ventricular geometry and function as well as myocardial viability and coronary anatomy is available when both MSCT and CMR are performed. This combined approach of these two imaging modalities provide clinically relevant information and may guide therapeutic decision making.