Right ventricular hypertrophy and diastolic dysfunction in arterial switch patients without pulmonary artery stenosis

OBJECTIVE

To assess pulmonary flow dynamics and right ventricular (RV) function in patients without significant anatomical narrowing of the pulmonary arteries late after the arterial switch operation (ASO) by using magnetic resonance imaging (MRI).

METHODS

17 patients (mean (SD), 16.5 (3.6) years after ASO) and 17 matched healthy subjects were included. MRI was used to assess flow across the pulmonary trunk, RV systolic and diastolic function, and RV mass.

RESULTS

Increased peak flow velocity (>1.5 m/s) was found across the pulmonary trunk in 14 of 17 patients. Increased RV mass was found in ASO patients: 14.9 (3.4) vs 10.0 (2.6) g/m2 in normal subjects (p<0.01). Delayed RV relaxation was found after ASO: mean tricuspid valve E/A peak flow velocity ratio = 1.60 (0.96) vs 1.92 (0.61) in normal subjects (p = 0.03), and E-deceleration gradients = -1.69 (0.73) vs -2.66 (0.96) (p<0.01). After ASO, RV mass correlated with pulmonary trunk peak flow velocity (r = 0.49, p<0.01) and tricuspid valve E-deceleration gradients (r = 0.35, p = 0.04). RV systolic function was well preserved in patients (ejection fraction = 53 (7)% vs 52 (8)% in normal subjects, p = 0.72).

CONCLUSIONS

Increased peak flow velocity in the pulmonary trunk was often observed late after ASO, even in the absence of significant pulmonary artery stenosis. Haemodynamic consequences were RV hypertrophy and RV relaxation abnormalities as early markers of disease, while systolic RV function was well preserved.

Accurate Detection of Stent-Graft Migration in a Pulsatile Aortic Model Using Roentgen Stereophotogrammetric Analysis

PURPOSE

To evaluate the feasibility and accuracy of Roentgen stereophotogrammetric analysis (RSA) versus computed tomography (CT) for detecting stent-graft migration in an in vitro pulsatile circulation model and to study the feasibility of a nitinol endovascular clip (NEC) as an aortic wall reference marker for RSA.

METHODS

An aortic model with stent-graft was constructed and connected to an artificial circulation with a physiological flow and pressure profile. Tantalum markers and NECs were used as aortic reference markers for RSA analysis. Stent-graft migrations were measured during pulsatile circulation with RSA and CT. CT images acquired with 64 x 0.5-mm beam collimation were analyzed with Vitrea postprocessing software using a standard clinical protocol and central lumen line reconstruction. RSA in the model with the circulation switched off was used as the reference standard to determine stent-graft migration. The measurement errors of RSA and CT were determined during pulsatile circulation.

RESULTS

The mean measurement error +/- standard deviation (maximum) of RSA during pulsatile circulation using the tantalum markers was -0.5+/-0.16 (0.7) mm. Using the NEC, the mean (maximum) measurement error was -0.4+/-0.25 (1.1) mm. The mean (maximum) measurement error of CT was -1.1+/-1.17 (2.8) mm.

CONCLUSION

RSA is an accurate and feasible tool to measure stent-graft migration in a pulsatile environment. Migration measurement with RSA was more accurate than CT in this experimental setup. The nitinol clip tested in this study is potentially feasible as an aortic reference marker in patients after endovascular repair.

Applications of multislice computed tomography in coronary artery disease

Multislice computed tomography (MSCT) provides high accuracy for noninvasive assessment of coronary artery disease (CAD). The introduction of the latest computed tomography (CT) technology allows comprehensive evaluation of various aspects of CAD, including the coronary calcium score, coronary artery stenoses, bypass patency, and myocardial function. Other applications, such as plaque characterization, first-pass perfusion imaging, and viability imaging using delayed contrast enhancement, are still under development and may demonstrate clinical utility in the future. Further improvements in CT hardware and imaging protocols are expected that may result in improved coronary artery imaging, new applications, and a significant reduction of radiation dose.

Right Ventricular Function in Patients with Acute Pulmonary Embolism: Analysis with Electrocardiography-synchronized Multi–Detector Row CT

PURPOSE

To prospectively assess electrocardiography (ECG)-synchronized multi-detector row computed tomography (CT) for the evaluation of right ventricular (RV) function in patients suspected of having pulmonary embolism (PE).

MATERIALS AND METHODS

All patients gave informed consent after the study details, including radiation exposure, were explained; institutional ethical committee approval was obtained. Nonsynchronized multi-detector row CT of the chest was performed in 66 consecutive patients (29 men, 37 women; mean age, 58 years+/-15 [standard deviation]) who were suspected of having PE. ECG-synchronized cardiac multi-detector row CT was performed to assess cardiac function. Dimension ratios for the RV and left ventricle (LV) were measured on nonsynchronized transverse and angulated four-chamber views. Furthermore, the RV end-diastolic and end-systolic volumes were measured on ECG-synchronized multi-detector row CT scans. An independent samples t test was performed to compare the mean value of different groups. An analysis of variance post hoc test was performed to investigate whether the values of the variables varied between groups.

RESULTS

PE was detected in 29 of 66 patients. The location of PE was categorized as central (n=17) or peripheral (n=12). The RV/LV dimension ratio was larger on the four-chamber view (P=.002), and RV end-systolic volume was larger (P=.01) and ejection fraction was lower (P=.01) in patients with PE. The RV end-systolic volumes and RV/LV volume ratios, as assessed by using ECG-synchronized multi-detector row CT, showed significant differences (P<.005) between patients with central PE and those with peripheral PE. However, the RV/LV dimensions on nonsynchronized images revealed no significant differences.

CONCLUSION

Retrospective ECG-synchronized multi-detector row CT facilitates detection of RV dysfunction, depending on pulmonary embolus location.

Detection of simulated nodules on clinical radiographs: dose reduction at digital posteroanterior chest radiography

PURPOSE

To determine to what extent dose reduction results in decreased detection of simulated nodules on patient digital posteroanterior (PA) chest radiographs.

MATERIALS AND METHODS

Raw data from 20 clinical digital PA chest images that were reported as having normal findings and that were obtained with a slot-scan charge-coupled device system were used. For research protocol that concerns data with patient identities concealed, institutional review board approval is not required. One hundred twenty nodules varying in size and signal intensity were digitally simulated and added to the chest images. Hard copies were printed to represent a 100% dose and, by adding noise, to represent simulated patient doses of 50%, 25%, and 12%. Four radiologists reviewed images. Each lesion was registered as "detected" or "not detected." A semiparametric logistic regression model was used for statistical analysis.

RESULTS

The decrease in radiation dose from 100% to 50%, 25%, or 12% had no effect on lesion detection in the lungs. The decrease in radiation dose had an effect on lesion detection in the mediastinum, as probabilities deteriorated from the 100% dose to the 50%, 25%, and 12% dose with each step. Probabilities of smaller detection rates when compared with that of the reference category (100% dose) were 0.97 (95% confidence interval [CI]: -0.86, 0.012) for the 50% dose, 1 (CI: -0.59, -0.61) for the 25% dose, and 1 (CI: -2.41, -1.22) for the 12% dose. CIs for the effects were on the log(odds). Detection probability decreased with smaller and lower signal intensity lesions.

CONCLUSION

At clinical digital radiography, dose reduction resulted in decreased observer detection of simulated nodules in the mediastinum but not in the lungs.

Aortic root dysfunctioning and its effect on left ventricular function in Ross procedure patients assessed with magnetic resonance imaging

BACKGROUND

This study evaluated the diameters and distensibility of the aortic root as well as the degree of aortic regurgitation (AR) and its effect on left ventricular (LV) function in patients 8.2 +/- 3.1 years after they underwent the Ross procedure, with a comparison of these parameters between patients and matched healthy subjects.

METHODS

Eighteen Ross procedure patients (16 male patients, age [mean +/- SD] 19.2 +/- 3.8 years) and 18 matched healthy subjects (16 male patients, age [mean +/- SD] 19.7 +/- 4.2 years) underwent magnetic resonance imaging. Measurements for diameters (at 4 levels) and the distensibility of the aortic root were performed using a steady-state free precession sequence. Aortic flow was assessed with a velocity-encoded phase-contrast sequence. Left ventricular systolic function was assessed with a gradient-echo sequence in the short-axis plane. Comparison of parameters was performed using the Mann-Whitney U test. Correlations between diameters, distensibility, AR fraction, and LV systolic function were expressed with Spearman rank correlation coefficients. Linear regression analysis was used to identify predictors of LV systolic dysfunction.

RESULTS

Aortic root diameters were increased in Ross procedure patients as compared with healthy subjects (mean difference 6.3-11.6 mm, P < or = .02 at all 4 levels). Distensibility of the aortic root was lower in patients (1.9 +/- 1.1 vs 7.8 +/- 3.3 mm Hg(-1), P < .01). An AR fraction > 5% was present in 14 of the 18 patients (mean AR fraction 8% +/- 5% vs 1% +/- 1%, P < .01). Left ventricular ejection fraction was lower in patients (50% +/- 6% vs 57% +/- 6%, P < .01). Dilatation, decreased distensibility, and AR fraction were correlated with impaired LV systolic function (P < .05 for all). The AR fraction predicted impaired LV systolic function (P < .01).

CONCLUSIONS

Magnetic resonance imaging shows dilatation and decreased distensibility of the aortic root, AR, and consequent impaired LV systolic function in patients after the Ross procedure.

MDCT Assessment of Right Ventricular Systolic Function

OBJECTIVE

The objective of our study was to validate using MDCT for the assessment of right ventricular (RV) function. MDCT with retrospective ECG gating was performed in 15 patients being evaluated for suspected cardiovascular disease. Echocardiography was performed for comparison. The MDCT images were reconstructed at 20 phase points over the cardiac cycle. The end-diastolic and end-systolic volumes of both ventricles were measured. Stroke volumes and ejection fractions were calculated from these data.

CONCLUSION

RV volumes can be accurately assessed using MDCT.

Contrast-detail evaluation and dose assessment of eight digital chest radiography systems in clinical practice

The purpose of this study was to assess contrast-detail performance and effective dose of eight different digital chest radiography systems. Digital chest radiography systems from different manufacturers were included: one storage phosphor system, one selenium-coated drum system, and six direct readout systems including four thin-film transistor (TFT) systems and two charge-coupled device (CCD) systems. For measuring image quality, a contrast-detail test object was used in combination with a phantom that simulates the primary and scatter transmission through lung fields (LucAl). Six observers judged phantom images of each modality by soft-copy reading in a four-alternative-forced-choice experiment. The entrance dose was also measured, and the effective dose was calculated for an average patient. Contrast-detail curves were constructed from the observer data. The blocked two-way ANOVA test was used for statistical analysis. Significant difference in contrast-detail performance was found between the systems. Best contrast-detail performance was shown by a CCD system with slot-scan technology, and the selenium-coated drum system was compared to the other six systems (p values <or=0.003). Calculated effective dose varied between 0.010 mSv and 0.032 mSv. Significant differences in contrast-detail performance and effective dose levels were found between different digital chest radiography systems in clinical practice.

Comparison of eight different digital chest radiography systems: variation in detection of simulated chest disease

OBJECTIVE

In a short period, a variety of technically different digital radiography chest systems have become available for clinical use. Our purpose was to assess the diagnostic performance of eight different digital radiography chest systems for detection of simulated chest disease under clinical conditions.

MATERIALS AND METHODS

Assessed were four different flat-panel detector systems, two different charge-coupled device systems, one selenium-coated drum, and one storage phosphor system. For each system, 10 chest images of an anthropomorphic chest phantom were obtained. Each image contained one to 12 simulated chest lesions. Eight radiologists performed soft-copy interpretations. Entrance dose was measured and effective dose calculated. A semi-parametric logistic regression model was used for statistical analysis.

RESULTS

Statistically significant differences were found in the diagnostic performance of the eight digital chest systems (p = 0.01). Best performance was observed with the charge-coupled device system with slot-scan technology, yielding a sensitivity of 46% (132 of 288) lesions detected. The performance of three flat-panel detectors and the selenium-drum system was not significantly different from the slot-scan charge-coupled device system. Fewer lesions were detected with the storage phosphor system than with all other digital technologies, with a sensitivity of 34% (99 of 288) lesions detected, slot-scan charge-coupled device system versus storage phosphor system, p < 0.001. The effective dose varied among the digital systems.

CONCLUSION

We found differences in diagnostic performance among the eight different digital chest systems. Differences in detection rates are predominantly explained by detector design.

[Percutaneous radiologic thermocoagulation treatment of liver, kidney and lung tumours]

Percutaneous image-guided radiofrequency ablation is mainly used for treatment of tumours in the skeleton, the liver, kidney and lung, in patients who are no (longer) candidates for surgical treatment. Sterile placement of the radiofrequency electrode, which is coupled to a radio-frequency generator, is image-guided. Heating causes cell-death. It has been shown in the literature that radiofrequency ablation is a safe and effective treatment method for local tumor control.

Digital Slot-Scan Charge-coupled Device Radiography versus AMBER and Bucky Screen-Film Radiography: Comparison of Image Quality in a Phantom Study

PURPOSE

To evaluate the image quality and performance of a chest digital radiography system and to compare this with the image quality and performance of advanced multiple-beam equalization radiography (AMBER) and Bucky screen-film radiography systems.

MATERIALS AND METHODS

The chest digital radiography system is a digital charge-coupled device (CCD) chest imaging unit that uses slot-scan technology. A contrast-detail test object was used in combination with a phantom that simulates the primary and scatter transmission for the lungs and mediastinum. Twelve phantom images were obtained with each modality (ie, CCD digital radiography and AMBER and Bucky screen-film radiography) and were judged by six observers. CCD digital radiography soft-copy reading was compared with AMBER hard-copy reading. To measure image quality, contrast-detail curves were constructed from the observer data. The Wilcoxon signed rank test was used for statistical analysis.

RESULTS

For the lung configuration, contrast-detail curves showed lower threshold depth for hard-copy images obtained with CCD digital radiography than for those obtained with Bucky screen-film radiography. For hard-copy images, the difference between contrast-detail curves for CCD digital radiography and those for Bucky screen-film radiography was statistically significant (P < .006). No significant difference was found between CCD digital radiography and AMBER for hard-copy images obtained in either the lung or mediastinum configuration. For the lung configuration, a lower threshold depth was observed for CCD digital radiography soft-copy reading than for AMBER hard-copy reading, with significantly different contrast-detail curves for CCD digital radiography soft copy and AMBER hard copy (P < .006). No significant difference was found between either system for the mediastinum configuration.

CONCLUSION

Contrast-detail curves indicate that image quality for the CCD chest system provides a digital alternative to AMBER and Bucky screen-film radiography.

Radiofrequency Ablation for Treatment of Symptomatic Low-flow Vascular Malformations after Previous Unsuccessful Therapy

Three patients with low-flow soft-tissue vascular malformations were treated with radiofrequency (RF) ablation. Other treatment options had proven unsuccessful. After RF ablation treatment, two patients were free of symptoms and one reported decreased symptoms followed by a return of symptoms within 1 year. No procedure-related complications occurred. It is suggested that RF ablation may be offered as an alternative treatment option for symptomatic vascular malformations when others have failed or are not possible.

Pituitary magnetic resonance imaging is not required in the postoperative follow-up of acromegalic patients with long-term biochemical cure after transsphenoidal surgery

After successful transsphenoidal surgery for acromegaly, life-long follow-up is required, because 10-15% of patients develop recurrence of disease. We assessed whether it is safe to perform postoperative follow-up with only biochemical evaluation in acromegalic patients initially cured by transsphenoidal surgery. We studied 32 patients cured after transsphenoidal surgery for acromegaly during a follow-up of 8.7 +/- 6.4 yr (mean +/- sd). Serial measurements of serum GH during glucose tolerance test and magnetic resonance imaging (MRI) scans were performed. Serial MRI scans were reevaluated by three independent neuroradiologists, who were blinded for the clinical and biochemical data, for growth of suspected tumor tissue. Twenty-three patients remained biochemically cured in the long term, whereas nine of the 32 patients developed recurrence of disease, indicated by elevated serum GH concentrations during glucose tolerance test and clinical symptoms/signs. None of the 23 patients with long-term biochemical cure showed growth of tumor tissue according to two neuroradiologists, whereas the third neuroradiologist assessed three of 23 patients as having tumor growth despite continuing biochemical cure. In the nine patients with biochemical recurrence, no tumor growth was found in the series of postoperative MRI scans, according to two of the three independent radiologists, whereas the third radiologist found tumor growth in four patients with recurrent disease. In conclusion, in patients with acromegaly, initially cured by transsphenoidal surgery, it appears safe to check for recurrent disease during long-term follow-up of these patients by biochemical markers only.

Rheumatoid Arthritis: Epidural Enhancement as an Underestimated Cause of Subaxial Cervical Spinal Stenosis

PURPOSE

To assess the frequency and site of subaxial spinal canal stenosis due to enhancing tissue in patients with rheumatoid arthritis.

MATERIALS AND METHODS

Data from 33 consecutive patients with rheumatoid arthritis were evaluated; these patients had undergone 1.5-T magnetic resonance imaging following gadolinium chelate administration, in combination with a frequency selective fat-suppression technique. Stenosis and enhancement were scored for each of six cervical spinal levels and were compared with results in a control population consisting of 16 patients with degenerative disease. Enhancement was scored as superficial or deep on the anterior and posterior sides from the cervical spinal cord. Differences between patient groups were tested by using the chi(2) test for trend and the Fisher exact test.

RESULTS

No significant difference was found in the frequency or severity of subaxial stenosis between rheumatoid arthritis and degenerative disease. Deep epidural enhancement was observed more often with rheumatoid arthritis than with degenerative disease both anterior (25 of 33 patients vs seven of 16 patients, respectively; P <.001) and posterior (24 of 33 patients vs two of 16 patients, respectively; P =.001) to the spinal cord. Enhancing stenosing tissue in rheumatoid arthritis frequently occurred anterior and posterior at the same time and at the same level, with segmental cufflike extension of enhancing tissue around the dural sac. Stenosing tissue enhanced more frequently with rheumatoid arthritis than with degenerative disease (22 of 33 vs four of 16 patients, respectively; P =.008).

CONCLUSION

In patients with rheumatoid arthritis, subaxial stenosis is frequently caused by enhancing epidural tissue. This enhancing tissue presumably represents pannus.

Digital Slot-Scan Charge-coupled Device Radiography versus AMBER and Bucky Screen-Film Radiography for Detection of Simulated Nodules and Interstitial Disease in a Chest Phantom

PURPOSE

To evaluate the diagnostic performance of full-field slot-scan charge-coupled device (CCD)-based digital radiography in the detection of simulated chest diseases in clinical conditions versus that of two screen-film techniques: advanced multiple beam equalization radiography (AMBER) and Bucky radiography.

MATERIALS AND METHODS

Simulated nodules and interstitial nodular and interstitial linear lesions were attached onto an anthropomorphic chest phantom. One hundred sixty-eight lesions were distributed over 25 configurations. A posteroanterior chest radiograph of each configuration was obtained with each technique. The images were presented to six observers. Each lesion was assigned one of two outcome scores: "detected" or "not detected." False-positive readings were evaluated. Differences between the imaging methods were analyzed by using a semiparametric logistic regression model.

RESULTS

For simulated nodules and interstitial linear disease, no statistically significant difference was found in diagnostic performance between CCD digital radiography and AMBER. The detection of simulated interstitial nodular disease was better with CCD digital radiography than with AMBER: Sensitivity was 71% (77 of 108 interstitial nodular lesions) with CCD digital radiography but was 56% (60 of 108 lesions) with AMBER (P =.041). Better results for the detection of all lesion types in the mediastinum were observed with CCD digital radiography than with Bucky screen-film radiography: Sensitivity was 45% (227 of 504 total simulated lesions) with CCD digital radiography but was 24% (119 of 504 lesions) with Bucky radiography (P <.001). There were fewer false-positive observations with CCD digital radiography (35 [5.7%] of 609 observations) than with Bucky radiography (47 [9.5%] of 497 observations; P =.012).

CONCLUSION

Differences were in favor of the full-field slot-scan CCD digital radiographic technique. This technique provides a digital alternative to AMBER and Bucky screen-film radiography.