Numerical Simulation of Airflow Patterns and Air Temperature Distribution during Inspiration in a Nose Model with Septal Perforation

Background

The most typical symptoms of patients with nasal septal perforation (SP) are crusting and recurrent nosebleed. The objective of the study was to determine the influence of SP on intranasal temperature profile and airflow patterns during inspiration by means of numerical simulation.

Methods

Two realistic bilateral models of the human nose with and without SP were reconstructed based on computed tomography (CT). A numerical simulation was performed. The intranasal air temperature distribution and airflow patterns during inspiration were displayed, analyzed, and compared.

Results

SP causes a highly disturbed airflow in the area of perforation. A spacious vortex within the perforation including various localized vortices was detected. A disturbed intranasal temperature distribution between the right and left nasal cavities developed.

Conclusions

The numerical simulation demonstrates the interaction between airflow patterns and heating of respiratory air. The disturbed airflow causes reduced air conditioning. This fact may contribute to crusting and recurrent nosebleed.

Low radiation dose in computed tomography: the role of iodine

Recent approaches to reducing radiation exposure during CT examinations typically utilize automated dose modulation strategies on the basis of lower tube voltage combined with iterative reconstruction and other dose-saving techniques. Less clearly appreciated is the potentially substantial role that iodinated contrast media (CM) can play in low-radiation-dose CT examinations. Herein we discuss the role of iodinated CM in low-radiation-dose examinations and describe approaches for the optimization of CM administration protocols to further reduce radiation dose and/or CM dose while maintaining image quality for accurate diagnosis. Similar to the higher iodine attenuation obtained at low-tube-voltage settings, high-iodine-signal protocols may permit radiation dose reduction by permitting a lowering of mAs while maintaining the signal-to-noise ratio. This is particularly feasible in first pass examinations where high iodine signal can be achieved by injecting iodine more rapidly. The combination of low kV and IR can also be used to reduce the iodine dose. Here, in optimum contrast injection protocols, the volume of CM administered rather than the iodine concentration should be reduced, since with high-iodine-concentration CM further reductions of iodine dose are achievable for modern first pass examinations. Moreover, higher concentrations of CM more readily allow reductions of both flow rate and volume, thereby improving the tolerability of contrast administration.

Small bowel imaging with MRI

Magnetic resonance imaging (MRI) has evolved as a powerful tool for the assessment of the small bowel. Strengths of MRI include the superb soft-tissue contrast, lack of radiation exposure, and the implementation of fast scanning techniques. Clinically relevant findings such as inflammation and tumor disease can be well-depicted. We describe in this article current techniques of small bowel MRI including its implementation and clinical outcome in comparison to other radiological and endoscopic procedures.

Comparison of inversion recovery and contrast-enhanced T1-weighted fat-suppressed sequences for the staging of cervical lymphoma

In a retrospective analysis with two readers blinded to the clinical information, coronal short tau inversion recovery (STIR) images were compared to contrast-enhanced fat-saturated T1-weighted imaging (T1 CEfs) in 51 cases of cervical lymphoma. Interrater reliability was good to excellent. Although sensitivity and subjective quality of the STIR sequence were higher than those of the T1 CEfs sequence (sensitivity 85%/72%, respectively), specificity (82%/95%) as well as positive likelihood ratio (4.65/15.93) was much lower. Therefore, contrast-enhanced sequences should be included in the primary staging of lymphoma.

[Radial MRI of the hip joint for evaluation of degenerative changes in the young adult: a comparison of different sequences]

AIM

Femoroacetabular impingement has been shown to be an important cause for the development of osteoarthritis of the hip joint. Radial MRI of the hip has proven to be the diagnostic procedure of choice to differentiate which patient to operate. While examinations after instillation of contrast agents have been described, new papers have shown high accuracy without contrast medium. Since instillation of contrast medium is considered painful and poses the risk of infection, it is not performed for MRI evaluation of the hip at our institution. However, the question as to which sequence to use has not been settled yet. Therefore, four frequently used sequences using the same resolution were compared.

MATERIALS AND METHODS

A retrospective analysis of T (1)-weighted (T (1)), T (2)-weighted (T (2)) and proton density sequences (the latter with and without fat saturation [PDfs and PD]) of 50 hips in 48 patients with femoro-acetabular impingement and developmental dysplasia of the hip was performed by two raters blinded to the clinical information. The different sequences were rated separately. Evaluated criteria were subjective imaging quality, power to differentiate acetabular from femoral cartilage as well as the labrum from the joint capsule, and localisation and characterisation of pathological changes in joint cartilage, the labrum and at the femoral head-neck junction.

RESULTS

Subjective imaging quality was assessed to be similar for T (1), PDfs and PD, whereas it was significantly worse for T (2). In discriminating specific intraarticular structures, however, only PDfs and PD were superior. The differentiation of acetabular from femoral cartilage was possible in only 44% and 40% of T (1) and T (2) images, but in 79% and 76% of PDfs and PD images. Similar results were found for the differentiation of the acetabular labrum from its vicinity, especially the joint capsule (36%, 35%, 77% and 74%, respectively). Intralabral pathology was seen in a comparable extent in all sequences. An intramedullary oedema at the head-neck junction, however, was significantly more frequent in PDfs only (67% vs. 0%, 17% and 10% for PDfs vs. T (1), T (2) and PD).

CONCLUSION

Despite their good subjective quality, T (1)- and T (2-)weighted sequences could not depict the acetabular labrum as efficiently as PD-weighted sequences. Concluding from our data, a PDfs sequence (possibly combined with a conventional PD sequence) is advantageous over T (1) and T (2) sequences. Intraarticular administration of contrast medium seems to be superfluous.

[Diagnostics of vascular diseases as a cause for acute abdomen]

Vascular pathologies are rare causes of an acute abdomen. If the cause is a vascular disease a rapid diagnosis is desired as vascular pathologies are associated with high mortality. A differentiation must be made between arterial and venous diseases. An occlusion of the superior mesenteric artery is the most common reason for acute mesenteric ischemia but intra-abdominal arterial bleeding is also of great importance. Venous pathologies include thrombotic occlusion of the portal vein, the mesenteric vein and the vena cava.Multi-detector computed tomography (MDCT) is predestined for the diagnostics of vascular diseases of the abdomen. Using multiphasic contrast protocols enables reliable imaging of the arterial and venous vessel tree and detection of disorders with high sensitivity and specificity. Although conventional angiography has been almost completely replaced by MDCT as a diagnostic tool, it is still of high importance for minimally invasive interventions, for example in the management of gastrointestinal bleeding.

Electronic colon-cleansing for CT colonography: diagnostic performance

BACKGROUND

The purpose of this study was to evaluate whether an electronic-colonic-cleansing (ECC) algorithm is beneficial for the diagnostic performance compared to a CT colonography (CTC) evaluation without electronic cleansing in tagged datasets.

METHODS

Two blinded readers evaluated CTC datasets from 79 patients with 153 colorectal polyps confirmed by optical colonoscopy. Cases were read in a randomized order with and without the use of electronic colon-cleansing software. Per-polyp sensitivity, per-polyp/per-patient specificity and reading times (with and without ECC) have been calculated and reported.

RESULTS

Per-polyp sensitivity for polyps >6 mm without using ECC was 60.4% (Reader 1: 59.7%, Reader 2: 61.1%), while polyps >10 mm were detected with a sensitivity of 58.3% (Reader 1: 66.7%, Reader 2: 50%). On electronically cleansed datasets, the sensitivity was 73.6% (Reader 1: 76.4%; Reader 2: 70.8%) for polyps >6 mm and 83.3% (Reader 1: 83.3%; Reader 2: 83.3%), respectively. Per-patient specificity was 75% without using cleansing (Reader 1: 68%, Reader 2: 82%) and 81.5% using ECC (Reader 1: 86%, Reader 2: 77%).

CONCLUSION

Reading CTC cases using ECC software improves sensitivity in detecting clinically relevant colorectal polyps.

[CT colonography: evaluation of two 3D algorithms in a screening population]

PURPOSE

The purpose of this multicenter study was to compare a dissection display and an endoluminal display for CT colonography (CTC) by means of detection rates and evaluation time in a screening collective.

MATERIALS AND METHODS

4 blinded readers evaluated CTC datasets from 42 patients with 55 endoscopically confirmed polyps. The datasets were read in a randomized order using two different 3D visualization methods (endoluminal view vs. dissection display; EBW 2.0.1, Philips Medical Systems, Best/NL). Patients underwent cathartic cleansing as well as stool and fluid tagging. All readers except one were experienced in performing CTC. The per-lesion/per-patient sensitivity, per-patient specificity, and evaluation time were calculated.

RESULTS

The overall per-lesion sensitivity using the dissection display (and endoluminal view) was 60% (53 %) for reader 1, 58% (60%) for reader 2, 67% (71%) for reader 3 and 55% (58%) for reader 4. The per-patient sensitivity using the dissection display (and endoluminal view) was 85% (85%) for reader 1, 80% (85%) for reader 2, 95% (90%) for reader 3 and 80% (80%) for reader 4. The per-patient specificity was 68% with dissection view (77% endoluminal view) for reader 1, 82% (82%) for reader 2, 59% (59%) for reader 3 and 82% (73%) for reader 4. The experienced readers were significantly faster using the perspective-filet view.

CONCLUSION

Using a dissection display of CTC datasets does not result in superior detection rates for polyps if datasets are stool and fluid-tagged. 3 out of 4 readers evaluated the datasets significantly faster with the dissection display.

Value of MDCT in preoperative local staging of rectal cancer for predicting the necessity for neoadjuvant radiochemotherapy

PURPOSE

Neoadjuvant therapy may reduce local rectal cancer recurrence after total mesorectum extirpation. This study was performed to assess whether multi-detector row CT (MDCT) is capable of reliably differentiating UICC I (surgery) from UICC II-IV (neoadjuvant therapy).

MATERIALS AND METHODS

29 patients underwent preoperative MDCT of the abdomen in a portal venous phase. Two blinded readers independently evaluated the datasets on a dedicated workstation using axial and coronal reformations. Local tumor extension (T), nodal status (N) and distant metastases (M) were evaluated and the UICC stage was determined. Findings were correlated with postoperative histology.

RESULTS

Histologically, 9 patients were UICC I; 20 UICC > I (II: 7; III: 11; IV: 2). Reader 1 correctly identified 3 / 9 as UICC I, overstaged 6 / 9, and correctly staged 20 / 20 as UICC > I. Reader 2 correctly identified 4 / 9 as UICC I, overstaged 5 / 9, understaged 4 / 20 and correctly staged 16 / 20 as UICC > I (PPV UICC I 100 % [50 %] reader 1 [reader 2], NPV 77 % [76 %], accuracy 79 % [69 %]). Reasons for overstaging by reader 1 (reader 2) included false-positive lymph nodes (LN) in 5 (5), overgrading T 1 tumors as T 3 in 1(0), and T overgrading in 4 / 5 (2 / 5) patients with false-positive LN.

CONCLUSION

MDCT failed to reliably identify UICC I in rectal cancer patients. Therefore, a strategy based solely on MDCT to identify patients who would benefit from neoadjuvant therapy does not seem appropriate.

Coronary MR imaging: navigator echo biofeedback increases navigator efficiency--initial experience

RATIONALE AND OBJECTIVES

The aim of this study was to investigate whether a respiratory biofeedback system could increase navigator efficiency and maintain image quality compared to conventional respiratory-gated magnetic resonance coronary angiography (MRCA).

MATERIALS AND METHODS

Eighteen healthy volunteers underwent MRCA using three different respiratory-gating protocols. A conventional expiratory free-breathing (FB) sequence was compared to two approaches using navigator echo biofeedback (NEB), a midinspiratory approach (NEBin) and an expiratory approach (NEBex). Navigator data reflecting the position of the diaphragm relative to a 3-mm gating window were made available to the subject using a video projector in combination with a Plexiglas screen and mirror goggles. Image quality was graded by two radiologists in consensus using a visual score ranging from 1 (not visible) to 4 (excellent vessel depiction).

RESULTS

The NEB approaches improved navigator efficiency (71.1% with NEBex and 68.0% with NEBin vs 42.2% with FB), thus reducing total imaging time. This difference was statistically significant (P(NEBin)=.007; P(NEBex)=.001). Image quality in the NEBex group was comparable to that in the FB group (median score, 2.44 vs 2.52), but it proved to be significantly lower (median score, 1.94 vs 2.52) for the right coronary artery and the left anterior descending coronary artery in the NEBin group.

CONCLUSION

NEB maintains image quality and significantly increases navigator efficiency, thereby decreasing total imaging time by about 40% compared to a conventional FB acquisition strategy.

MDCT of the abdomen

Multi-detector row computed tomography (MDCT) enables fast and thin acquisition of the abdominal anatomy. This allows multi-pass multi-planar studies that can be obtained during defined circulatory phases. When bolus timing is adequate, arterial phases with high contrast levels provide "free lunch" CT angiographies eliminating the need for diagnostic angiographies in most cases. In addition to established clinical indications for abdominal CT such as preoperative MDCT of the liver or pancreas, MDCT of the abdomen is especially gaining ground in the work up for acute abdominal pain and abdominal trauma and is opening new indications for MDCT of the gastrointestinal tract. Indications for gastrointestinal MDCT include tumors, bleeding and ischemia of the small and large bowel as well as diverticulitis. The question of whether to use positive or negative contrast material for bowel distention for MDCT of the gastrointestinal tract is still a controversial issue. In selected cases, modifying the protocol to perform a "CT enteroclysis" might improve sensitivity and specificity in depicting small bowel tumors or inflammatory changes such as in Crohn's disease. The most common gastrointestinal mesenchymal tumor is the gastrointestinal stromal tumor (GIST). MDCT may show hypervascular submucosal masses. Acute gastrointestinal (GI) bleeding is common with patients presenting with melena, hematemesis or hematochezia. In addition to the established initial work-up MDCT is beginning to establish itself for this indication. It may be especially helpful in the work up of obscure bleeding. Another relatively rare but important cause for acute abdominal pain is mesenteric ischemia. It may be caused by many conditions and may mimic various intestinal diseases. Bowel ischemia severity ranges from transient superficial changes of the intestinal mucosa to life-threatening transmural bowel wall necrosis. CT can demonstrate changes in ischemic bowel segments accurately, is often helpful in determining the primary cause of ischemia, and can demonstrate important coexistent findings or complications.

Acute gastrointestinal bleeding: value of MDCT

Contrast-enhanced multidetector row helical computed tomography (MDCT) scanning is establishing itself as a rapid, noninvasive, and accurate diagnostic method in suspected acute gastrointestinal bleeding. Active bleeding can be depicted as an area of focal high attenuation within the bowel lumen on arterial phase MDCT images. New MDCT technologies facilitate three-dimensional image reconstruction, and higher temporal resolution is available with new MDCT scanner generations. This allows for the acquisition of arterial- and portal-venous phase images of the whole abdomen, revealing potential bleeding sources and simultaneously depict morphological changes in the abdomen, such as intestinal tumors. This article gives an overview of available diagnostic modalities in assessing gastrointestinal (GI) tract hemorrhage, with a special emphasis on new MDCT technology.

Comparison of manual and automated size measurements of lung metastases on MDCT images: Potential influence on therapeutic decisions

PURPOSE

The goal of this study was to evaluate the influence of automated measurement of diameter, area, and volume from chest CT scans on therapeutic decisions of lung nodules as compared to manual 2-D measurements.

PATIENTS AND METHOD

The retrospective study involved 25 patients with 75 lung metastases. Contrast enhanced CT scans (16 row) of the lung were performed three times during chemotherapy with a mean time interval of 67.9 days between scans. In each patient, three metastases were evaluated (n=225). Automatic measurements were compared to manual assessment for the following parameters: diameter, area, and density. The influence on the therapeutic decisions was evaluated using the RECIST criteria.

RESULTS

The maximum diameter measured by the automatic application was on an average 27% (S.D. 39; CI: 0.22-0.32; p<0.0001) higher than the maximum diameter with manual assessment, and the differences depended on metastases size. Based on diameter calculation, manual and automated assessment disagreed in up to 32% of therapeutic decisions. Volumetric assessment tended towards more changes in therapy as compared to diameter calculation. The calculation of mean transversal area of metastases was 36% (S.D. 0.305; CI: -0.40 to -0.32; p<0.0001) less with automated measurement. Therapeutic strategy would be changed in up to 25.7% of nodules using automated area calculation. Automated assessment of nodules' area and volume could influence the therapeutic decisions in up to 51.4% of all nodules. Density of the nodules was not validated to determine the influence on therapeutic decisions.

CONCLUSION

There is a discrepancy between the manual and automated size measurement of lung metastases which could be significant.

Detection and localization of acute upper and lower gastrointestinal (GI) bleeding with arterial phase multi-detector row helical CT

The purpose of this study was to evaluate the accuracy of multi-detector row helical CT (MDCT) for detection and localization of acute upper and lower gastrointestinal (GI) hemorrhage or intraperitoneal bleeding. Thirty-six consecutive patients with clinical signs of acute bleeding underwent biphasic (16- or 40-channel) MDCT. MDCT findings were correlated with endoscopy, angiography or surgery. Among the 36 patients evaluated, 26 were examined for GI bleeding and 10 for intraperitoneal hemorrhage. Confirmed sites of GI bleeding were the stomach (n = 5), duodenum (n = 5), small bowel (n = 6), large bowel (n = 8) and rectum (n = 2). The correct site of bleeding was identifiable on MDCT in 24/26 patients with GI bleeding. In 20 of these 24 patients, active CM extravasation was apparent during the exam. Among the ten patients with intraperitoneal hemorrhage, MDCT correctly identified the bleeding source in nine patients. Our findings suggest that fast and accurate localization of acute gastrointestinal and intraperitoneal bleeding is achievable on MDCT.

CT colonography: an update

Computed tomographic (CT) colonography (CTC)--also known as "virtual colonoscopy"--was first described more than a decade ago. As advancements in scanner technology and three-dimensional (3D) postprocessing helped develop this method to mature into a potential option in screening for colorectal cancer, the fundamentals of the examination remained the same. It is a minimally invasive, CT-based procedure that simulates conventional colonoscopy using 2D and 3D computerized reconstructions. The primary aim of CTC is the detection of colorectal polyps and carcinomas. However, studies reveal a wide performance variety in regard to polyp detection, especially for smaller polyps. This article reviews the available literature, discusses established indications as well as open issues and highlights potential future developments of CTC.

Multiple gastrointestinal stromal tumors and bilateral pheochromocytoma in neurofibromatosis

The coincidence of a gastrointestinal stromal tumor (GIST) and a neuroendocrine tumor (NET) in neurofibromatosis type 1 (NF1) is described only five times within the literature. We report on a 63 year old Caucasian female with the rare condition of neurofibromatosis type 1 coinciding with recurrent gastrointestinal stromal tumor plus bilateral pheochromocytoma (PCC). After a history of palpitations and dizziness that lasted for years, a left adrenal mass was detected by CT. Laparotomy revealed a pheochromocytoma of the left adrenal gland while an ileoterminal GIST was found incidentally intraoperatively. After six months contralateral PCC and multiple recurrent GIST were resected again. After four years the patient is doing well without any signs of further recurrent tumors. Discussion includes review of the literature.

Beschwerden im Verlauf nach konservativ behandelten distalen Radiusfrakturen - Prädiktoren aus der initialen Röntgenaufnahme

PURPOSE

Radius fractures are frequent in adults, and the long-term results of conservative treatment remain disappointing. This study examines predictors for the clinical outcome in the initial radiograph. This will help to identify patients who will benefit from surgical treatment.

MATERIALS AND METHODS

A cohort study including a standardized telephone interview (Cooney score) was used to identify all conservatively treated patients with a distal radius fracture over a five-year period. The additional selection criteria were: over 15 years old, initial X-ray available, patient reachable by phone for the follow-up interview. The following measurements were taken from the initial radiograph: radius-base angle, radial shortening, radiopalmar angle and intraarticular displacement. Correlations and a simple test to predict negative outcome were computed.

RESULTS

Of the initially identified 2211 patients with distal radius fracture, 179 also fulfilled the other criteria. The patients were 56.2 years old on average (standard deviation SD = +/- 22.45 years) and 72 % were female. 60 % of the fractures were on the right side. The average follow-up was 4.3 years (SD +/- 1.66). The Cooney score results averaged 85 points (with 100 being the optimal and maximum score), indicating good or very good functional results in the long term follow-up for 61 % of patients. However, 31 % received a rating of fair or poor and therefore had an unfavorable outcome. With respect to the correlations, age and shortening of the radius (but not gender) had a significant influence on the functional result. Using an age of 75 years or above and a radial shortening of at least 4 mm to predict an unfavorable outcome, the sensitivity is only 16 %, but the positive predictive value is 73 % and the specificity is 96 %.

CONCLUSION

In the analysis of the initial radiographs after distal radius fracture, age and radial shortening primarily correlate with functional results after four years after conservative treatment. Using the values age > or = 75 and radial shortening > or = 4 mm, it is possible to predict an unfavorable functional outcome with a positive predictive value of 73 %. This could aid in the indication of operative treatment.

MR neurography with multiplanar reconstruction of 3D MRI datasets: an anatomical study and clinical applications

INTRODUCTION

Extracranial MR neurography has so far mainly been used with 2D datasets. We investigated the use of 3D datasets for peripheral neurography of the sciatic nerve.

METHODS

A total of 40 thighs (20 healthy volunteers) were examined with a coronally oriented magnetization-prepared rapid acquisition gradient echo sequence with isotropic voxels of 1 x 1 x 1 mm and a field of view of 500 mm. Anatomical landmarks were palpated and marked with MRI markers. After MR scanning, the sciatic nerve was identified by two readers independently in the resulting 3D dataset.

RESULTS

In every volunteer, the sciatic nerve could be identified bilaterally over the whole length of the thigh, even in areas of close contact to isointense muscles. The landmark of the greater trochanter was falsely palpated by 2.2 cm, and the knee joint by 1 cm. The mean distance between the bifurcation of the sciatic nerve and the knee-joint gap was 6 cm (+/-1.8 cm). The mean results of the two readers differed by 1-6%.

CONCLUSION

With the described method of MR neurography, the sciatic nerve was depicted reliably and objectively in great anatomical detail over the whole length of the thigh. Important anatomical information can be obtained. The clinical applications of MR neurography for the brachial plexus and lumbosacral plexus/sciatic nerve are discussed.

MDCT angiography of the spinal vasculature and the artery of Adamkiewicz

OBJECTIVE

The purpose of our study was to prospectively assess 40-MDCT technology in combination with adapted brain reconstruction algorithms to visualize the spinal vasculature, in particular the artery of Adamkiewicz and its anatomic variants.

SUBJECTS AND METHODS

One hundred patients underwent contrast-enhanced MDCT of the thoracolumbar junction with collimation of 40 x 0.625 mm. The adapted brain algorithm reconstructed the spinal canal with a field of view of 90 mm at 0.6-mm slice thickness. Curved multiplanar reformations identified the artery of Adamkiewicz as a continuous vascular tract extending from the aortic orifices of the intercostal or lumbar arteries via the anterior radiculomedullary artery to the anterior spinal artery. Segment of origin and length were noted. Diameter and contrast-to-noise ratio (CNR) were evaluated along the posterior branch, the radiculomedullary artery, the artery of Adamkiewicz, and the anterior spinal artery. Univariate general linear model analysis with Bonferroni post hoc corrections evaluated whether laterality, segment of origin, and length of the artery of Adamkiewicz showed a sex-specific propensity. Multivariate general linear model analysis assessed whether spinal vascular diameters and intraluminal CNR showed correlations with sex, laterality, and segment of origin. Finally, the luminal diameters of the feeding posterior branches were statistically compared with those of the ipsilateral and contralateral adjacent posterior branches.

RESULTS

Successful depiction of the artery of Adamkiewicz was achieved in all patients; longitudinally the artery measured 40.1 +/- 13.51 mm. In 63% of patients it originated from the left side of the body, and in 74% it originated from the level of the 10th-12th thoracic vertebrae. Duplications were found in 5% of patients. Segmental distribution, laterality, and length did not show significant sex-specific differences (p > 0.05). The vascular diameter and luminal contrast did not show significant differences caused by sex, laterality, or segment of origin (p > 0.05). The diameter of the posterior branches (2.8 +/- 0.71 mm) arising in the segments of origin showed a significantly wider lumen than any of the other posterior branches (contralateral, 1.9 +/- 0.32 mm; upper ipsilateral, 2.0 +/- 0.47 mm; lower ipsilateral, 1.9 +/- 0.39 mm) (p < 0.0001).

CONCLUSION

Contrast-enhanced 40-MDCT technology, in combination with an adapted brain reconstruction algorithm, can depict the artery of Adamkiewicz and its anatomic variants.

Spectral Coronary Multidetector Computed Tomography Angiography

OBJECTIVE

To assess ex vivo specimens of atherosclerotic coronary arteries by dual energy (DE) multidetector computed tomography (MDCT) imaging, and to correlate depicted vessel lumen morphology and detected tissue characteristics with histopathologic analysis.

METHODS

Coronary arteries were imaged on a 16-slice MDCT using a DE protocol consisting of a 90- and 140-kV scan. Coronary arteries were perfused with iodine- and gadolinium-based contrast agents. The DE K-edge subtractions were performed. Regions-of-interest were placed on histopathologically/radiographically-matched vascular lumen and wall, fibromuscular and calcified plaque, and fat tissues. Vascular/tissue contrast-to-noise ratios (CNR) were calculated, and their dependence on tissue type and contrast agent type was statistically evaluated.

RESULTS

Tissue CNR analysis confirmed that all tissue types were successfully distinguished. Vascular wall and fibromuscular plaque achieved a significant increase in CNR ratios when DE techniques were used compared with 140 kV protocols.

CONCLUSIONS

Spectral DE MDCT imaging of ex vivo atherosclerotic coronary arteries allows successful tissue characterization and enhances depiction of coronary lumen.

Synergy of MDCT and Cine MRI for the Evaluation of Cardiac Motility

OBJECTIVE

The objective of our study was to validate the feasibility of the synergistic use of cardiac MR and CT data sets for ventricular motility analysis and to correlate measurement variability with underlying heart rate.

SUBJECTS AND METHODS

Twenty patients underwent concurrent ECG-gated MDCT and MRI for evaluation of ventricular motility, expressed as ventricular wall thickening and motion. Initially, individual measurement repetition series were analyzed by determining intraobserver variability and detecting intraobserver bias related to heart rates. Subsequently, absolute measurement differences of CT or MR data were statistically evaluated. Finally, absolute measurement differences were correlated with underlying heart rates by curve estimation regression.

RESULTS

Analysis of measurement reproducibility proved that data variability was dependent on only the anatomic localization of the analyzed ventricular segment, not on the imaging technique used or underlying heart rate, in normofrequent patients. Comparing MR and CT image data sets, no statistically significant differences were identified when ventricular motility was evaluated based on data sets of either imaging technique in normofrequent patients. Tachycardic frequencies, above 100 beats per minute, led to exponential error propagation due to insufficient temporal resolution of the current CT technology.

CONCLUSION

This study proved that cardiac motility assessment based on ECG-gated CT and MR data sets resulted in comparable ventricular function results for normofrequent patients; however, the high spatial resolution of cardiac MDCT cannot compensate for the lack of temporal resolution in patients with tachycardia, thus emphasizing the necessity of reporting ventricular motility analysis results in combination with heart rate to allow consideration of this possible cause for measurement variation.