Diagnostic Accuracy of Split-Bolus Single-Phase Contrast-Enhanced Cone-Beam CT for the Detection of Liver Tumors before Transarterial Chemoembolization

Purpose

To evaluate detectability of hepatocellular carcinoma (HCC) using split-bolus cone-beam CT in intraindividual comparison between cone-beam CT and contrast-enhanced MR imaging.

Percutaneous ablation of lymph node metastases using CT-guided high-dose-rate brachytherapy

Objective:

To assess the technical feasibility, safety and clinical outcome of CT-guided high-dose-rate brachytherapy (CT-HDRBT) for achieving local tumour control (LTC) in isolated lymph node metastases.

Methods:

From January 2008 to December 2011, 10 patients (six males and four females) with isolated nodal metastases were treated with CT-HDRBT. Five lymph node metastases were para-aortic, three were at the liver hilum, one at the coeliac trunk and one was a left iliac nodal metastasis. The mean lesion diameter was 36.5 mm (range 12.0–67.0 mm). Patients were followed up by either contrast-enhanced CT or MRI 6 weeks and then every 3 months after the end of treatment. The primary end point was LTC. Secondary end points included primary technical effectiveness rate, adverse events and progression-free survival.

Results:

The first follow-up examination after 6 weeks revealed complete coverage of all nodal metastases treated. There was no peri-interventional mortality or major complications. The mean follow-up period was 13.2 months (range 4–20 months). 2 out of 10 patients (20%) showed local tumour progression 9 and 10 months after ablation. 5 out of 10 patients (50%) showed systemic tumour progression. The mean progression-free interval was 9.2 months (range 2–20 months).

Conclusion:

CT-HDRBT is a safe and effective technique for minimally invasive ablation of nodal metastases.

Advances in knowledge:

CT-HDRBT of lymph node metastases is feasible and safe. CT-HDRBT might be a viable therapeutic alternative to obtain LTC in selected patients with isolated lymph node metastases.Metastatic spread to lymph nodes is a common event in the course of many thoracic and abdominal malignancies and has considerable clinical implications [1]. The management of metastatic disease is complex, and treatment modalities reported in the literature are heterogeneous, depending largely on the localisation of metastatic nodes as well as the patient’s performance status and treatment history. Hence, the optimal management for patients with isolated lymph node metastasis has not yet been established.Although the results of several studies suggest a potential benefit to the cytoreduction of isolated nodal disease among patients with ovarian, hepatocellular, renal or colorectal carcinoma, data on the role of repeated surgical resection of confined lymph node metastases are limited, and response rates of nodal metastases to chemotherapy are inconsistent [2–7].Over the past decades, interventional oncology has expanded its role, and minimally invasive tumour ablation techniques have become a cornerstone in the multimodal treatment of oncological patients. The clinical success of thermal ablation techniques, such as radiofrequency ablation (RFA), has generated a large body of literature on the treatment of liver and lung tumours, while data on its use for the treatment of lymph node metastases remain scarce. CT-guided high-dose-rate brachytherapy (CT-HDRBT) is a radio-ablative technique that was established about 10 years ago to overcome the limitations of thermal ablative techniques [8]. Features such as high accuracy in dose distribution and applicability regardless of tumour diameter and location have contributed to the attractiveness of this technique. In recent years, several studies have reported encouraging results for the treatment of lung and liver tumours as well as extrahepatic and extrapulmonary malignancies [9–12]. The purpose of the present study is to report the results of CT-HDRBT for achieving local tumour control (LTC) in the treatment of isolated lymph node metastases.     

Low-dose computed tomography to detect body-packing in an animal model

Objective

To assess the possible extent of dose reduction for low-dose computed tomography (CT) in the detection of body-packing (ingested drug packets) as an alternative to plain radiographs in an animal model.

Materials and methods

Twelve packets containing cocaine (purity >80%) were introduced into the intestine of an experimental animal (crossbred pig), which was then repeatedly examined by abdominal CT with stepwise dose reduction (tube voltage, 80 kV; tube current, 10-350 mA). Three blinded readers independently evaluated the CT datasets starting with the lowest tube current and noted the numbers of packets detected at the different tube currents used. In addition, 1 experienced reader determined the number of packets detectable on plain abdominal radiographs and ultrasound.

Results

The threshold for correct identification of all 12 drug packets was 100 mA for reader 1 and 125 mA for readers 2 and 3. Above these thresholds all 3 readers consistently identified all 12 packets. The effective dose of a low-dose CT scan with 125 mA (including scout view) was 1.0 mSv, which was below that of 2 conventional abdominal radiographs (1.2 mSv). The reader interpreting the conventional radiographs identified a total of 9 drug packets and detected 8 packets by abdominal ultrasound.

Conclusions

Extensive dose reduction makes low-dose CT a valuable alternative imaging modality for the examination of suspected body-packers and might replace conventional abdominal radiographs as the first-line imaging modality.     

Coronary artery stenosis quantification using multislice computed tomography

RATIONALE AND OBJECTIVES: Reliable noninvasive detection of stenoses with multislice computed tomography (MSCT) is feasible. This study's aim was to analyze the agreement, correlation, and reliability of MSCT with conventional coronary angiography as the reference standard for quantification of coronary artery stenoses. MATERIALS AND METHODS: A total of 118 significant (at least 50%) coronary artery stenoses with a reference vessel diameter of at least 1.5 mm in 62 patients were analyzed by MSCT using 16 detector rows (Aquilion, Toshiba, Otawara, Japan), multisegment reconstruction, and voxel sizes of 0.35x0.35x0.5 mm. The degree of stenosis on MSCT and quantitative coronary angiography (QCA) was measured by correlating the difference between the reference vessel diameter (average of 2 measurements directly proximal and distal to the stenosis) and the stenotic vessel diameter to the reference vessel diameter. RESULTS: Correlation between the percent diameter stenosis determined by MSCT (78.2+/-13.6%) and QCA (76.0+/-14.8%) was significant (P<0.001) but only moderately so (R=0.51). Bland-Altman analysis revealed no systematic under- or overestimation with MSCT but large limits of agreements (+/-27.6%). Also the limits of agreement for interobserver agreement (reliability) of MSCT data were considerably large (+/-24.8%). Among the 27 coronary artery stenoses with a reference diameter of at least 3.5 mm, there was improved correlation (R=0.80) and the limits of agreement between MSCT and QCA were significantly smaller (+/-17.3%, P<0.008). The agreement between MSCT and QCA was not significantly different for stenoses with no calcification or only calcium spots (+/-28.2%) as compared with those with moderate-or-severe calcifications (+/-27.3%; P=0.8). MSCT allowed correct classification of coronary stenoses into low-grade (below 75%) and high-grade stenoses (at least 75%), in 62% (73 of 118). CONCLUSIONS: The accuracy and reliability of coronary artery stenosis quantification with MSCT using isotropic voxel sizes and multisegment reconstruction is still too low to recommend routine clinical application because of rather low agreement, correlation, and reliability. Despite these limitations, the current results demonstrate the potential of MSCT for reliable and accurate quantification of coronary artery stenoses in the near future provided that further improvements in spatial and temporal resolution will be achieved.     

Multisegment and halfscan reconstruction of 16-slice computed tomography for assessment of regional and global left ventricular myocardial function

RATIONALE AND OBJECTIVES: We sought to prospectively compare multisegment and halfscan reconstruction of 16-slice computed tomography (CT) for the assessment of regional and global left ventricular myocardial function with magnetic resonance imaging (MRI) as the reference standard. MATERIALS AND METHODS: Forty-two patients underwent CT with 16 x 0.5-mm detector collimation. Electrocardiogram-gated reconstructions were generated with multisegment reconstruction (using up to 4 segments correlated with the raw data of up to 4 heartbeats) and standard halfscan reconstruction. Steady-state free-precession cine MRI was acquired within 24 hours. RESULTS: More normal myocardial segments were identified correctly with multisegment (95%, 620/656) compared with halfscan reconstruction (88%, 582/656) of CT (P < 0.001). Also, the accuracy (92% [657/714] vs. 87% [620/714]) and rate of nondiagnostic segments (0% vs. 5% [33/714]) were significantly better when using multisegment reconstruction (P < 0.001). The image quality with multisegment reconstruction was significantly superior to that achieved with halfscan reconstruction (P < 0.001). In the assessment of global left ventricular function, multisegment and halfscan reconstruction of CT showed high correlations for all parameters with MRI, whereas Bland-Altman analysis revealed smaller limits of agreement for assessment of myocardial mass with multisegment reconstruction (P = 0.025), but no significant differences between both reconstruction techniques in the measurement of left ventricular volumes as compared with MRI. CONCLUSIONS: Multisegment reconstruction of 16-detector row CT improves image quality and assessment of regional wall motion compared with standard halfscan reconstruction.     

Comparison between the image quality of multisegment and halfscan reconstructions of non-invasive CT coronary angiography

The purpose of this study was to compare the image quality of multisegment and halfscan reconstructions of multislice computed tomography (MSCT) coronary angiography. 126 patients with suspected coronary artery disease and uninfluenced heart rates were examined by 16-slice CT before they underwent invasive coronary angiography. Multisegment and halfscan reconstructions were performed in all patients, and subjective image quality, overall vessel length, vessel length free of motion artefacts and contrast-to-noise ratios (CNRs) were compared for both techniques. The diagnostic accuracy of both approaches was compared with the results of invasive coronary angiography. Overall image quality scores of multisegment reconstruction were superior to those of halfscan reconstruction (13.3±2.1 vs 11.9±2.9; p<0.001). Multisegment reconstruction depicted significantly longer overall coronary vessel lengths (p<0.001) and larger vessel proportions free of motion artefacts in three of the four main coronary arteries. CNRs in the left main, left anterior descending and left circumflex coronary arteries were significantly higher when multisegment reconstruction was used (p<0.001). Overall accuracy was higher for multisegment reconstruction compared with halfscan reconstruction (87% vs 62%). In conclusion, multisegment reconstruction significantly improves image quality and diagnostic accuracy of MSCT coronary angiography compared with standard halfscan reconstruction, resulting in vessel lengths depicted free of motion comparable to those of CT performed in patients given β-blockers to lower heart rates.Non-invasive coronary angiography is an alternative approach to conventional coronary angiography in patients with suspected coronary artery disease (CAD) with high clinical [1–4] and economic [5] relevance. Recently, multislice computed tomography (MSCT) has developed into the most reliable non-invasive method for imaging of the whole coronary artery tree [6]. The susceptibility of MSCT to motion artefacts can only be overcome by systematic pre-scan β-blockade to lower heart rates to target values below 65 beats per minute (bpm). Recent studies have shown that β-blocker administration is necessary even on 64-slice scanners [4, 7–11]. Motion artefacts result from a relatively long acquisition window, which is determined by the gantry rotation time in standard halfscan reconstruction. In contrast, multisegment reconstruction [12] reduces the acquisition time by using up to four different segments from up to four consecutive heart beats [13]. In this way, an acquisition window as short as one-eighth of the gantry rotation time can be achieved [14]. In a small retrospective study of 34 patients with suspected CAD, multisegment reconstruction showed superior image quality and diagnostic accuracy compared with halfscan reconstruction. Based on these results, it was suggested that there is no need for β-blocker administration when multisegment reconstruction is used [15]. However, a recently published subgroup analysis of patients with different heart rates showed that image quality and diagnostic performance of multisegment reconstruction varied with heart rate [16]. Therefore, the use of β-blockers was recommended in patients with heart rates above 75 bpm when using multisegment reconstruction.In this study, we analysed prospectively the overall image quality and diagnostic accuracy of multisegment reconstruction compared with halfscan reconstruction in a large consecutive group of patients with uninfluenced heart rates to determine whether systematic β-blockade is needed.