Change in contrast enhancement of HCC on 1-month follow-up CT after local radiotherapy: an early predictor of final treatment response

Background

The purpose of this study was to evaluate the change in contrast enhancement of HCC on 1-month follow-up CT after local radiotherapy (RT) as an early predictor of final treatment response.

Materials

Fifty patients who underwent local RT for HCCs had both pre-RT and post-RT CT scans including 1-month follow-up CT. We assessed the final treatment response by using the change in maximal tumor size on 6-12-month follow-up CT scan after RT. We also evaluated the change in tumor enhancement between pre-RT and 1-month follow-up CT scans.

Results

A final treatment response was achieved in 27 (54%) of 50 patients, who showed either a complete response (n = 11) or a partial response (n = 16). Compared with non-responsive patients (n = 23), responsive patients showed a significant decrease in tumor enhancement on 1-month follow-up CT after RT in both objective and subjective analyses (each P < 0.001).

Conclusion

The change in contrast enhancement of HCC seen on the 1-month follow-up CT in patients after local RT may be used as an early predictor of final treatment response.     

The influence of liquid crystal display monitors on observer performance for the detection of interstitial lung markings on both storage phosphor and flat-panel-detector chest radiography

Purpose

To compare observer performance with a flat-panel liquid crystal display (LCD) monitor and with a high-resolution gray-scale cathode ray tube (CRT) monitor in the detection of interstitial lung markings using a silicon flat-panel-detector direct radiography (DR) and storage phosphor computed radiography (CR) in a clinical setting.

Materials and methods

We displayed 39 sets of posteroanterior chest radiographs from the patients who were suspected of interstitial lung disease. Each sets consisted of DR, CR and thin-section CT as the reference standard. Image identities were masked, randomly sorted, and displayed on both five mega pixel (2048 × 2560 × 8 bits) LCD and CRT monitors. Ten radiologists independently rated their confidence in detection for the presence of linear opacities in the four fields of the lungs; right upper, left upper, right lower, and left lower quadrant. Performance of a total 6240 (39 sets × 2 detector systems × 2 monitor system × 4 fields × 10 observers) observations was analyzed by multi-reader multi-case receiver operating characteristic (ROC) analysis. Differences between monitor systems in combinations of detector systems were compared using ANOVA and paired-samples t-test.

Results

Area under curves (AUC) for the presence of linear opacities measured by ROC analysis was higher on the LCDs than CRTs without statistical significance (p = 0.082). AUC was significantly higher on the DR systems than CR systems (p = 0.006). AUC was significantly higher on the LCDs than CRTs for DR systems (p = 0.039) but not different for CR systems (p = 0.301).

Conclusion

In clinical conditions, performance of the LCD monitor appears to be better for detecting interstitial lung markings when interfaced with DR systems.     

Correlation between high-resolution computed tomography and galactomannan antigenemia in adult hematologic patients at risk for invasive aspergillosis

Objectives

To analyse the predominant radiological pattern of pulmonary lesions in adult hematologic patients at risk for invasive aspergillosis (IA) together with the results of serial serum Aspergillus galactomannan antigen testing (GM).

Material and methods

In a prospective study for patients at high risk of aspergillus pulmonary infection, serum GM were performed 2-3 times per week during the periods of high risk for IA and high-resolution CT (HRCT) was performed in case of abnormal chest X-ray (CXR) and/or persistent fever after 5 days of antibiotic treatment. Changes on HRCT scan were classified as airway IA and angioinvasive IA. IA was classified as proven or probable in accordance with the definitions stated by the European Organization for Research and Treatment of Cancer/Mycosis Study Group (EORTC-MS). Positive GM testing was not considered as microbiological criterion.

Results

38 hematological patients were diagnosed of probable (n = 28) or proven (n = 10) IA. 55% patients had a neutrophil count less than 500 mm⁻³ (n = 21), and 37% patients ≥2 risk factors for IA. All probable IA were diagnosed by bronchoalveolar lavage (BAL). Proven IA was reached by positive histopathologic and culture results of samples obtained by autopsy (n = 4), percutaneous (n = 3) or transbronchial biopsy (n = 3). 18 patients had airway IA, and 60% had a GM level ≥1.5. 20 patients were diagnosed of angioinvasive IA from which 80% had a GM level ≥1.5.

Conclusion

Serum GM levels may be lower in patients with airway IA than in those with an angioinvasive form. HRCT and serum GM are complementary tests in the diagnosis of IA.     

MDCT arthrography of the wrist: Diagnostic accuracy and indications

Purpose

To evaluate the diagnostic accuracy and indications of arthrography with Multidetector Computed Tomography (arthro-MDCT) of the wrist in patients with absolute or relative contraindications to magnetic resonance imaging (MRI) studies and in patients with periarticular metal implants using diagnostic arthroscopy as the gold standard.

Materials and methods

After intra-articular injection of iodixanol and volumetric acquisition, 43 wrists in patients of both genders (18 females, 25 males, age range 32-60 years) were examined with a 16-detector-row CT scanner. Fifteen patients had prior wrist surgery. The patients had arthralgia, degenerative and traumatic arthropathies as well as limited range of motion, but no radiologically detected fractures. All examinations were interpreted by two experienced musculoskeletal radiologists.The findings were compared with arthroscopic findings carried out within 28 days of the CT study.

Results

In non-operated and operated wrists the comparison between arthro-MDCT and arthroscopy showed sensitivity, specificity and accuracy ranging between 92% and 94% for triangular fibrocartilage complex (TFCC), between 80% and 100% for intrinsic ligaments located within the proximal carpal compartment, and between 94% and 100% for articular cartilage.Inter-observer agreement between two radiologists, in the evaluation of all types of lesions, was almost perfect (k = 0.96) and statistically significant (p < 0.05).

Conclusions

Arthro-MDCT of the wrist provides an accurate diagnosis to identify chondral, fibrocartilaginous and intra-articular ligament lesions in patients who cannot be evaluated by MRI, and in post-surgical patients.     

Potential dependent superiority of gold nanoparticles in comparison to iodinated contrast agents

Purpose

To identify the benefits in image contrast enhancement using gold nanoparticles (AuNPs) compared to conventional iodinated contrast media.

Materials and methods

Gold nanoparticles and iodinated contrast media were evaluated for contrast enhancement at various X-ray tube potentials in an imaging phantom. Iopromide and AuNP suspension were equalized according to molar concentration of radiopaque element (0.5077 Mol/L). Contrast-to-noise ratio is used to quantify contrast enhancement. Both projectional radiographic (40-80 kVp) and computed tomography (CT) (80-140kVp) imaging modalities were examined.

Results and conclusions

Findings indicate 89% improvement in CNR at low energies near the mammographic range (40 kVp). However, as expected no significant difference in enhancement was observed at potentials commonly used for angiography (around 80 kVp) probably due to the k-edge influence for iodine. At the highest energies typically available in computed tomography, significant improvement in contrast enhancement using gold nanoparticles is obtained, 114% greater CNR than that produced by iodine at 140 kVp. Experimental findings for 70-120 kVp spectra correlate well with the theoretical calculations based on linear attenuation coefficients. Superior attenuation of gold nanoparticles at low and high kVp potentials support their further (pre)clinical evaluation.     

Added value of 80 kVp images to averaged 120 kVp images in the detection of hepatocellular carcinomas in liver transplantation candidates using dual-source dual-energy MDCT: Results of JAFROC analysis

Background

To assess the added value of 80 kVp images to weighted average 120 kVp images for detecting hepatocellular carcinomas (HCCs) using dual-source, dual-energy MDCT.

Materials and methods

Forty-one HCCs in 42 patients who underwent liver transplantation (LT) were included. All patients underwent quadruple-phase CT using a 64-row dual-source, dual-energy MDCT with 80 kVp and 140 kVp. For 120 kVp, a linear blending ratio of 0.3 was chosen. Interval reviews for both simulated 120 kVp images without and with pure 80 kVp data were performed independently by two radiologists. They detected HCCs using a 4-point confidence scale. Tumor-to-liver contrast-to-noise ratio (CNR) was calculated and compared between the 80 kVp and simulated 120 kVp images. The additional diagnostic value of 80 kVp images was evaluated by jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis.

Results

There were 41 HCCs on pathology and 37 of the 41 HCCs were depicted on CT scan. The mean CNR of the 37 HCCs in late arterial and portal-phase images was significantly better in the 80 kVp images than in 120 kVp images. The average JAFROC figure of merit, however, was not significantly improved when 80 kVp was added. Furthermore, the number of false-positives was significantly increased in reader 1 when adding 80 kVp data.

Conclusion

The addition of 80 kVp CT images to simulated 120 kVp images did not significantly improve the detection of HCCs despite of the significantly better CNR of 80 kVp images.     

Dynamic magnetic resonance imaging for assessment of minimally invasive pelvic floor reconstruction with polypropylene implant

Introduction

The purpose of the study was to assess the usefulness of dynamic MRI in patients with pelvic organ prolapse after pelvic floor repair with polypropylene mesh.

Materials and methods

Fifteen consecutive patients (mean age 66.5 years) who were scheduled for either anterior (n = 9) or posterior (n = 6) pelvic floor repair were prospectively evaluated by clinical assessment and dynamic MRI 1 day before and 3 months after surgery. MRI diagnoses and MRI measurements of relevant anatomical points at rest and on straining were analysed before and after surgery.

Results

At follow-up assessment 93.3% of all patients were clinically cured. Dynamic MRI showed newly developed (n = 6) or increased (n = 6) pelvic organ prolapse in 80% (n = 12) of all patients 3 months after pelvic floor repair. Most of them (n = 11; 91.7%) affected the untreated pelvic floor compartment. On straining anatomical points of reference in the anterior pelvic floor compartment were significantly (p < 0.05) elevated after anterior repair and rectal bulging was significantly (p = 0.036) reduced after posterior pelvic floor repair.

Conclusions

In this study dynamic MRI could verify the effective support of anterior and posterior pelvic floor structures by anterior and posterior polypropylene implant respectively. But dynamic MRI demonstrates if one compartment of the pelvic floor is repaired another compartment frequently (73.3%) develops dysfunction. These results did not correspond to clinical symptoms on short-term follow-up (3 months). Studies with long-term follow-up are necessary to prove if dynamic MRI can reliably identify clinically significant pelvic organ prolapse after pelvic floor repair before the onset of symptoms.     

To be or not to be: Significance of lymph nodes on pretreatment CT in predicting survival of rectal cancer patients

Purpose

To assess the extent to which pretreatment imaging of lymph nodes by computed tomography (CT) predicts survival of patients with rectal cancer.

Materials and methods

We retrospectively analyzed 70 patients with rectal cancer, who had pretreatment CT and curative surgery between December 1999 and October 2003. These patients were followed until December 2007, ensuring minimal follow-up time of 49 months. Two radiologists who reviewed the CT images on workstations had no prior access to clinical and treatment information regarding the selected patients. The parameters assessed for survival analysis were as follows: patient age, sex, CEA and CA199 level, preoperational therapy, tumor location, serosal invasion, largest diameters and numbers of lymph nodes on pretreatment CT. Kaplan-Meier survival curves, the log-rank test, and the multivariate Cox proportional hazards model were used to evaluate the prognostic value of the parameters.

Results

Using pretreatment CT as prognostic tool, we found that both size and number of lymph nodes correlated with the overall survival of patients with rectal cancer. The data proved that a diameter smaller than 8 mm for the largest lymph node was correlated with prolonged survival (P < 0.001). Meanwhile, patients with more than 4 lymph nodes had a significantly worse disease-specific survival (P = 0.042). Both parameters are independent prognostic factors (hazard ratio 4.910 and 3.563) and could predict the overall survival of rectal cancer patients.

Conclusion

The lymph node size and number, as determined by pretreatment CT, is an important clinical prognostic factor in patients with rectal cancer. The pretreatment CT findings could be used to predict survival and plan appropriate therapies.     

Low dose prospective ECG-gated delayed enhanced dual-source computed tomography in reperfused acute myocardial infarction comparison with cardiac magnetic resonance

Purpose

To determine whether prospective electrocardiogram (ECG)-gated delayed contrast-enhanced dual-source computed tomography (DCE-DSCT) can accurately delineate the extension of myocardial infarction (MI) compared with delayed enhanced cardiac MR (DE-MR).

Material and methods

Eleven patients were examined using dual-source CT and cardiac MR in 2 weeks after a first reperfused MI. DCE-DSCT scan protocol was performed with prospective ECG-gating sequential scan model 7 min after contrast administration. In a 17-model, infarcted myocardium detected by DE-MR was categorized as transmural and subendocardial extension. Segment of infarcted location and graded transmurality were compared between DCE-MDCT and DE-MR.

Results

In all eleven patients, diagnostic quality was obtained for depicting delayed enhanced myocardium. Agreement between DCE-DSCT and MR was good on myocardial segment based comparison (kappa = 0.85, p < 0.001), and on transmural and subendocardial infarction type comparison (kappa = 0.82, p < 0.001, kappa = 0.52, p < 0.001, respectively). CT value was higher on infarcted region than that of normal region (100.02 ± 9.57 HU vs. 72.63 ± 7.32 HU, p < 0.001). Radiation dose of prospectively ECG-gating protocol were 0.99 ± 0.08 mSv (0.82-1.19 mSv).

Conclusions

Prospective ECG-gated DCE-DSCT can accurately assess the extension and the patterns of myocardial infarction with low radiation dose.     

Hepatic caudate vein in Budd-Chiari syndrome: Depiction by using magnetic resonance imaging

Objective

To study the visibility of the caudate vein and its diameter on MR imaging in healthy people and in patients with Budd-Chiari syndrome.

Materials and methods

In this study there were 14 patients with Budd-Chiari syndrome and 54 healthy subjects without hepatic lesion or liver disease, all of whom had upper abdominal enhanced MRI. The visibility of the caudate vein and its diameter on MR images was compared between Budd-Chiari patients and healthy subjects, and among Budd-Chiari patients, the correlation between the visibility of caudate vein and extrahepatic collaterals were compared.

Results

Caudate vein was noted in 64% of patients with Budd-Chiari syndrome and in 7% of healthy subjects (P = 0.000). The diameter of the caudate vein visualized on MR imaging in Budd-Chiari syndrome was significantly larger than that in healthy group (7.3 ± 3.9 mm vs 2.6 ± 0.6 mm, P = 0.037). Among Budd-Chiari patients, both caudate vein and extrahepatic collateral veins were noted in 9 patients, only extrahepatic collateral veins were noted in 4 patients and neither caudate vein nor extrahepatic collateral veins were noted in 1 patient. No correlation was found between the visibility of caudate vein and that of extrahepatic collateral vein in patients with Budd-Chiari (P = 0.375).

Conclusion

Gadolinium enhanced dynamic MR imaging can visualize hepatic caudate vein frequently. The visibility and dilation of hepatic caudate veins on MR imaging in Budd-Chiari syndrome were more frequent than in control subjects. MR depiction of a caudate vein may help differentiate Budd-Chiari from cirrhosis.     

Speckle reduction approach for breast ultrasound image and its application to breast cancer diagnosis

Objectives

To retrospectively evaluate the effects of a speckle reduction algorithm on radiologists’ diagnosis of malignant and benign breast lesions on ultrasound (US) images.

Methods

Using a database of 603 breast (US) images of 211 cases (109 benign lesions and 102 malignant ones), the original and speckle-reduced images were assessed by five radiologists and final assessment categories were assigned to indicate the probability of malignancy according to BI-RADS-US. The diagnostic sensitivity and specificity were investigated by the areas (Az) under the receiver operating characteristic (ROC) curves.

Results

The sensitivity and specificity of breast lesions on Ultrasound images improved from 88.7% to 94.3%, from 68.6% to 75.2%, respectively, and the area (Az) under ROC curve of diagnosis also increased from 0.843 to 0.939, Z = 4.969, there were significant differences in the Az between the original breast lesions and speckle-reduced ones on Ultrasound images (P < 0.001). The diagnostic accuracy of breast lesions had been highly improved from 78.67% to 92.73% after employing this algorithm.

Conclusions

The results demonstrate the promising performance of the proposed speckle reduction algorithm in distinguishing malignant from benign breast lesions which will be useful for breast cancer diagnosis.     

Low-dose adaptive sequential scan for dual-source CT coronary angiography in patients with high heart rate: Comparison with retrospective ECG gating

Purpose

To explore feasibility of dual-source CT (DS-CT) prospective ECG-gated coronary angiography in patients with heart rate (HR) higher than 70 beat per minute (bpm), and evaluate image quality and radiation dose with comparison to retrospective ECG-gated spiral scan.

Materials and methods

One hundred patients who underwent DS-CT coronary angiography (DS-CTCA) with mean HR higher than 70 bpm but below 110 bpm were enrolled in the study, 50 were scanned by adaptive sequential scan and another 50 were analyzed by retrospectively gated CT scan. The imaging quality of coronary artery segments in the two groups was evaluated using a four-point grading scale by two independent reviewers. Patient radiation dose was calculated by multiplying dose length product by conversion coefficient of 0.017.

Results

There was no significant difference between the two groups for mean HR (p = 0.305), HR variability (p = 0.103), body mass index (p = 0.472), and scan length (p = 0.208). There was good agreement for image quality scoring between the two reviewers (Kappa = 0.72). Coronary evaluability of adaptive sequential scan was 99.7% (608 of 610 segments), while that of retrospective gated scan was 98.7% (614 of 622 segments), showing similar coronary evaluability (p = 0.061). Effective doses of adaptive sequential scan and retrospective gated scan were 5.1 ± 1.6 and 11.8 ± 4.5 mSv, respectively (p < 0.001), showing that adaptive sequential scan reduced radiation dose by 57% compared with that of retrospective gated scan.

Conclusions

In patients with 70-110 bpm HR, DS-CTCA adaptive sequential scan shows similar image quality as retrospective ECG-gated spiral scan with 57% reduction of radiation dose.     

Chronic lower extremity lymphedema: A comparative study of high-resolution interstitial MR lymphangiography and heavily T2-weighted MRI

Purpose

To assess the role of heavily T2-weighted image and interstitial MR lymphangiography (MRL) for the visualization of lymphatic vessels in patients with disorders of the lymphatic circulation.

Methods

Forty lower extremities in 31 patients (9 bilateral and 22 unilateral) with primary lymphedema were examined by heavily T2-weighted image and indirect MRL. Maximum-intensity projection (MIP) was used to reconstruct the images of the lymphatic system. Two experienced radiologists analyzed the images with regard to the differences in image quality, number of lymphatic vessels, its maximum diameter and two other findings: accumulated lymph fluid in the tissue and honeycombing pattern.

Results

The beaded appearance of the affected vessels in 73 leg segments of 40 lower extremities were present on both modalities 3D MIP. Larger amount of the dilated lymphatic vessels were visualized on heavily T2-weighted image than that on MRL (p = 0.003) and the maximum diameter of it was 4.28 ± 1.53 mm on heavily T2-weighted image, whereas 3.41 ± 1.05 mm on MRL (p < 0.01). The dilated lymphatic vessels on MRL showed better image quality and greater SNR and CNR than that on heavily T2-weighted image (p < 0.01). The regions of accumulated lymph fluid and the honeycombing pattern extent were identified on heavily T2-weighted image scored statistically higher than that on MRL (p < 0.01).

Conclusion

The heavily T2-weighted imaging has greater sensitivity and the MRL image has higher legibility for detecting the pathologically modified lymphatic vessels and accompanying complications non-invasively. Combining these two MR techniques can accurately access the pathological changes in the lower extremity with lymphedema.     

The thickness of the A1 pulleys reflects the disability of hand mobility in scleroderma. A pilot study using high-frequency ultrasound

Background

Hand involvement in scleroderma is a serious concern. Clinical tests to asses hand dysfunction are based on the experience of the clinician.

Objective

To asses if utrasonographic (US) measurement of A1 pulley thickness may be used as an indicator of hand mobility in scleroderma.

Materials and methods

Institutional review board approval and patient informed consent was obtained. Twenty-eight patients affected suffering from scleroderma and 40 healthy controls were prospectively evaluated by two blinded radiologists with US, with a transducer operating at 17 MHz. A1 pulley thickness was measured and correlated with the Hand Mobility in Scleroderma Test (HAMIS) and disease duration.

Results

The thickness of the A1 pulley was greater in sclerodermic patients than in controls (p < 0.05). Intra and inter-observer agreement were better for ultrasound (0.94;0.88) than for HAMIS tests (0.71;0.70). A good correlation between pulley thickness, hand mobility and disease duration was found (r = 0.78, p < 0.018; r = 0.54, p < 0.05).

Conclusion

A1 pulley thickness measured on ultrasound correlates with hand mobility and disease duration. Ultrasound is an useful tool to evaluate hand disability in scleroderma.     

Ileal Crohn's disease: MRI with endoscopic correlation

Purpose

To evaluate activity staging of Crohn's disease (CD) measured with MR-enterography using ileoscopy as reference standard.

Materials and methods

A prospective study was made of 61 patients with CD. All patients underwent MR-enterography and ileoscopy. MRI activity was measured by means of an ad hoc developed score, as well as by analysis of the imaging findings, and was compared with the SES-CD score obtained via ileoscopy. Examinations were performed using a 1.0 T scanner.

Results

MRI score discriminates between active and inactive disease with an area under the ROC curve of 0.941. Overall correlation with the standard reference SES-CD score was moderate to strong (Spearman's r = 0.62 p < 0.001).Agreement between both methods in staging patients with ileal CD as inactive, mild or moderate to severe was good (Cohen's κ = 0.60). Differences in means of the MRI activity scores of the three groups showed statistical significance (p < 0.01).

Conclusions

The MRI score is a reliable predictor of activity in ileal CD and can stage patients in a way comparable to endoscopy. 1.0 T scans are valid for performing radiological evaluation of ileal Crohn's disease.     

Diffusion-weighted MRI in cervical lymph nodes: Differentiation between benign and malignant lesions

Objective

Purpose of our study was to assess the potential role of diffusion-weighted imaging (DWI) in the differential diagnosis between benign and malignant nodes.

Subject and methods

We enrolled 32 subjects: 14 with benign lymphadenopathy, 17 patients with histologically proved malignant disease before beginning treatment and 1 patient with lymphoma after chemotherapeutic treatment.In all patients we used fast spin echo T2-weighted images in axial and coronal planes, fast spin echo T1-weighted images before and after contrast medium of administration in axial and coronal planes.Before contrast administration diffusion sequences were acquired on the axial and coronal plane (b factor of 0.500 and 1000 s/mm²) and then apparent diffusion coefficient (ADC) maps were reconstructed.

Results

On diffusion images, 13/14 patients with benign nodes showed low signal intensity and had high signal on ADC maps, whereas all patients with malignant diseases appeared hyperintense on diffusion images and with low signal intensity on ADC maps. Only a patient with tuberculosis showed a low ADC value. The mean ADC value of malignant nodes was about 0.85 × 10⁻³ mm²/s, the mean value of benign nodes was 1.448 × 10⁻³ mm²/s; this difference was statistically significant (p < 0.01). The mean ADC value of treated nodes was 1.75 × 10⁻³ mm²/s. The best threshold value was 1.03 × 10⁻³ mm²/s, obtaining a sensitivity of 100% and a specificity of 92.9%.

Conclusions

Diffusion imaging could be considered an important supportive tool for the diagnosis of enlarged cervical lymphadenopathies.     

Dose performance and image quality: dual source CT versus single source CT in cardiac CT angiography

Objective

To evaluate dose performance and image quality of 64-slice dual source CT (DSCT) in comparison to 64-slice single source CT (SSCT) in cardiac CT angiography (CTA).

Methods

100 patients examined by DSCT and 60 patients scanned by SSCT were included in this study. Objective indices such as image noise, contrast-to-noise ratio and signal-to-noise ratio were analyzed. Subjective image quality was assessed by two cardiovascular radiologists in consensus using a four-point scale (1 = excellent to 4 = not acceptable). Estimation of effective dose was performed on the basis of dose length product (DLP).

Results

At low heart rates (<70 bpm), image quality of SSCT was equivalent to that of DSCT (P > 0.05), but, at high heart rates (>70 bpm), DSCT provided robust image quality (P < 0.05). The average effective dose of SSCT was 9.3 ± 0.9 mSv at low heart rates (<70 bpm) while, the average estimated effective doses of DSCT were 9.1 ± 1.3 mSv, 8.3 ± 1.1 mSv, 7.9 ± 1.1 mSv, 6.9 ± 0.7 mSv, and 5.9 ± 1.3 mSv, corresponding to heart rates of 50-59 bpm, 60-69 bpm, 70-79 bpm, 80-89 bpm, and 90-100 bpm.

Conclusion

For cardiac CTA, both DSCT and SSCT can get good image quality at low heart rates (<70 bpm) with a similar radiation dose, but, at high heart rates (>70 bpm), DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT.     

High resolution T2 weighted liver MR imaging using functional residual capacity breath-hold with a 1.0-Tesla scanner

Purpose

During acquisition of rapid high resolution (HR) T2 weighted (T2W) liver magnetic resonance (MR) images using a 1.0-Tesla (T) scanner, the liver is segmented into odd and even sections that are acquired at two different times using the multi-breath-hold (MBH) strategy. Misalignment between the two breath-hold (B-H) images may result in the occurrence of a blind area and a decrease in diagnostic accuracy. Here, a functional residual capacity (FRC) B-H method was developed to overcome this problem.

Material and methods

Twenty-five volunteers were enrolled. The sagittal images were reconstructed from whole liver transverse images. When the B-H phases are different, misalignment may occur in the craniocaudal and anterior-posterior (AP) directions. In this study, misalignments of the abdominal wall were measured in the AP direction. The misalignment was compared between four B-H phases, maximum inspiration (MI), maximum expiration (ME), voluntary expiration (VE) and FRC using one-way repeated measures ANOVA. Differences between groups were compared using the t-test for multi-group comparisons. In addition, qualitative analysis of misalignment was performed between VE and FRC in 52 clinical patients and the χ² test was performed.

Results

The misalignment widths of FRC, ME, MI and VE B-Hs were 2.7 ± 3.8, 6.4 ± 7.4, 9.1 ± 8.4 and 6.0 ± 6.7 mm, respectively. Misalignment of the liver position using FRC was significantly smaller than for the other B-H methods (p < 0.05). Significant differences between the VE B-H and FRC B-H were also observed in the qualitative analysis (p < 0.05).

Conclusion

The liver positions obtained when using FRC B-H were significantly more reproducible than when using the other B-H methods. The FRC B-H method resulted in a reduction in the blind area and an extension of the diagnostic area to the whole liver.     

3D automatic exposure control for 64-detector row CT: Radiation dose reduction in chest phantom study

Purpose

The purpose of this study was to determine the utility of three-dimensional (3D) automatic exposure control (AEC) for low-dose CT examination in a chest phantom study.

Materials and methods

A chest CT phantom including simulated focal ground-glass opacities (GGOs) and nodules was scanned with a 64-detector row CT with and without AEC. Performance of 3D AEC included changing targeted standard deviations (SDs) of image noise from scout view. To determine the appropriate targeted SD number for identification, the capability of overall identification with the CT protocol adapted to each of the targeted SDs was compared with that obtained with CT without AEC by means of receiver operating characteristic analysis.

Results

When targeted SD values equal to or higher than 250 were used, areas under the curve (Azs) of nodule identification with CT protocol using AEC were significantly smaller than that for CT protocol without AEC (p < 0.05). When targeted SD numbers at equal to or more than 180 were adapted, Azs of CT protocol with AEC had significantly smaller than that without AEC (p < 0.05).

Conclusion

This phantom study shows 3D AEC is useful for low-dose lung CT examination, and can reduce the radiation dose while maintaining good identification capability and good image quality.     

Usefulness of multislice spiral computed tomography coronary angiography in patients with acute chest pain in the emergency department

Background

Despite reports that multislice spiral computed tomography (MSCT) has high sensitivity and specificity in preselected patient populations, the routine clinical feasibility and utility of MSCT coronary angiography in patients with acute chest pain in the emergency department remains uncertain.

Objectives

We sought to determine whether 16-slice MSCT coronary angiography can provide diagnostically useful images in patients with acute chest pain in the emergency department.

Methods

Ninety-eight patients in the emergency department (41 men, 57 women; mean age ± SD, 48.1 ± 11.9 y) with acute chest pain underwent MSCT coronary angiography. Coronary calcium (Agatston) scoring was performed, followed by contrast-enhanced MSCT. Images were evaluated for mean image quality (MIQ) and for degree of stenosis. These data were correlated with body mass index (BMI; in kg/m²), heart rate, beat-to-beat variation, and calcium score to assess their influence on image quality.

Results

The 28 patients (29%) with nondiagnostic MIQs had significantly higher BMIs (mean ± SD, 32.9 ± 9.1 vs 28.9 ± 6.7; P < 0.05) and heart rates (mean ± SD, 71.0 ± 11.9 beats/min vs 65.6 ± 9.9 beats/min; P < 0.05) than patients with diagnostic MIQs. Forty-five patients (46%) had at least 1 nondiagnostic coronary segment. These patients had significantly higher heart rates (mean ± SD, 70.5 ± 10.3 vs 64.1 ± 13.7; P < 0.05) than patients with only diagnostic-quality scans. Image quality correlated inversely and strongly with BMI and heart rate.

Conclusions

Sixteen-slice MSCT coronary angiography cannot routinely provide diagnostically useful images in patients with acute chest pain in the emergency department.