Evaluation of the role of lung volume and airway size and shape in supine-predominant obstructive sleep apnoea patients.

BACKGROUND AND OBJECTIVE: This study aimed to evaluate the involvement of airway cross-sectional area and shape, and functional residual capacity (FRC), in the genesis of obstructive sleep apnoea (OSA) in patients with supine-predominant OSA. METHODS: Three groups were recruited: (i) supine OSA, defined as a supine apnoea-hyponoea index (AHI) at least twice that of the non-supine AHI; (ii) rapid eye movement (REM) OSA, defined as REM AHI at least twice the non-REM AHI and also selected to have supine AHI less than twice that of the non-supine AHI (i.e. to be non-positional); and (iii) no OSA, defined as an AHI less than five events per hour. The groups were matched for age, gender and body mass index. Patients underwent four-dimensional computed tomography scanning of the upper airway in the supine and lateral decubitus positions. FRC was measured in the seated, supine and lateral decubitus positions. RESULTS: Patients with supine OSA demonstrated a significant decrease in FRC of 340 mL (P = 0.026) when moving from the lateral to supine position compared to controls with no OSA, and REM OSA patients. We found no differences between groups in upper airway size and shape. However, all groups showed a significant change in airway shape with the velopharyngeal airway adopting a more elliptoid shape (with the long axis laterally oriented), with reduced anteroposterior diameter in the supine position. CONCLUSIONS: A fall in FRC when moving lateral to supine in supine OSA patients may be an important triggering factor in the generation of OSA in this patient group.

Dynamic four-dimensional computed tomography (4D CT) imaging for re-entry risk assessment in re-do sternotomy - first experience.

BACKGROUND: Repeat cardiac surgeries are well known to have higher rates of complications, one of the important reasons being injuries associated with re-do sternotomy. Routine imaging with CT can help to minimise this risk by pre-operatively assessing the anatomical relation between the sternum and the underlying cardiovascular structures, but is limited by its inability to determine the presence and severity of functional tethering and adhesions between these structures. However, with the evolution of wide area detector MD CT scanners, it is possible to assess the presence of tethering using the dynamic four-dimensional CT (4D CT) imaging technique. METHODS: Nineteen patients undergoing re-do cardiac surgery were pre-operatively imaged using dynamic 4D CT during regulated respiration. The datasets were assessed in cine mode for presence of differential motion between sternum and underlying cardiovascular structures which indicates lack of significant tethering. RESULTS: Overall, there was excellent correlation between preoperative imaging and intraoperative findings. The technique enabled our surgeons to meticulously plan the procedures and to avoid re-entry related injuries. CONCLUSIONS: Our initial experience shows that dynamic 4D CT is useful in risk stratification prior to re-do sternotomy by determining the presence or absence of tethering between sternum and underlying structures based on assessment of differential motion. Furthermore we determined the technique to be superior to non-dynamic assessment of retrocardiac tethering.

320-row CT coronary angiography predicts freedom from revascularisation and acts as a gatekeeper to defer invasive angiography in stable coronary artery disease: a fractional flow reserve-correlated study.

OBJECTIVES: To determine the accuracy of 320-row multidetector coronary computed tomography angiography (M320-CCTA) to detect functional stenoses using fractional flow reserve (FFR) as the reference standard and to predict revascularisation in stable coronary artery disease. METHODS: One hundred and fifteen patients (230 vessels) underwent M320-CCTA and FFR assessment and were followed for 18 months. Diameter stenosis on invasive angiography (ICA) and M320-CCTA were assessed by consensus by two observers and significant stenosis was defined as ≥50%. FFR ≤0.8 indicated functionally significant stenoses. RESULTS: M320-CCTA had 94% sensitivity and 94% negative predictive value (NPV) for FFR ≤0.8. Overall accuracy was 70%, specificity 54% and positive predictive value 65%. On receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) for CCTA to predict FFR ≤0.8 was 0.74 which was comparable with ICA. The absence of a significant stenosis on M320-CCTA was associated with a 6% revascularisation rate. M320-CCTA predicted revascularisation with an AUC of 0.71 which was comparable with ICA. CONCLUSIONS: M320-CCTA has excellent sensitivity and NPV for functional stenoses and therefore may act as an effective gatekeeper to defer ICA and revascularisation. Like ICA, M320-CCTA lacks specificity for functional stenoses and only has moderate accuracy to predict the need for revascularisation. KEY POINTS: • Important information about the heart is provided by 320-row multidetector CT coronary angiography (M320-CCTA). • M320-CCTA accurately detects and excludes functional stenoses determined by fractional flow reserve (FFR). • Non-significant stenoses on M320-CCTA associated with fewer cardiac events and less revascularisation. • M320-CCTA may act as a gatekeeper for invasive angiography and inappropriate revascularisation. • Like ICA, M320-CCTA only has moderate accuracy to predict vessels requiring revascularisation.

Computed tomography stress myocardial perfusion imaging in patients considered for revascularization: a comparison with fractional flow reserve.

AIMS: Adenosine stress computed tomography myocardial perfusion imaging (CTP) is an emerging non-invasive method for detecting myocardial ischaemia. Its value when compared with fractional flow reserve (FFR), a highly accurate index of ischaemia, is unknown. Our aim was to determine the diagnostic accuracy of CTP and its incremental value when used with computed tomography coronary angiography (CTA) for detecting ischaemia compared with FFR. METHODS AND RESULTS: Forty-two patients (126 vessel territories), who had at least one ≥50% angiographic stenosis on invasive angiography considered for non-urgent revascularization, were included and underwent FFR and CT assessment, including CTP, delayed contrast enhancement scan and CTA all acquired using 320-detector row CT, and prospective ECG gating. Fractional flow reserve was determined in 86 territories subtended by vessels with ≥50% stenosis upon visual assessment. Fractional flow reserve ≤0.8 was considered to indicate significant ischaemia. Computed tomography myocardial perfusion imaging correctly identified 31/41 (76%) ischaemic territories and 38/45 (84%) non-ischaemic territories. Per-vessel territory sensitivity, specificity, positive, and negative predictive values of CTP were 76, 84, 82, and 79%, respectively. The combination of a ≥50% stenosis on CTA and perfusion defect on CTP was 98% specific for ischaemia, while the presence of <50% stenosis on CTA and normal perfusion on CTP was 100% specific for exclusion of ischaemia. Mean radiation for CTP and combined CT was 5.3 and 11.3 mSv, respectively. CONCLUSION: Computed tomography myocardial perfusion imaging is moderately accurate in identifying perfusion defects associated with ischaemia as assessed by FFR in patients considered for revascularization. In territories, where CTA and CTP are concordant, CTA/CTP is highly accurate in the detection and exclusion of ischaemia. This is achievable with acceptable radiation exposure using 320-detector row CT and prospective ECG gating.

Abnormal vocal cord function in difficult-to-treat asthma.

RATIONALE: Upper airway dysfunction may complicate asthma but has been largely ignored as an etiological factor. Diagnosis using endoscopic evaluation of vocal cord function is difficult to quantify, with limited clinical application. OBJECTIVES: A novel imaging technique, dynamic 320-slice computerized tomography (CT), was used to examine laryngeal behavior in healthy individuals and individuals with asthma. METHODS: Vocal cord movement was imaged using 320-slice CT larynx. Healthy volunteers were studied to develop and validate an analysis algorithm for quantification of normal vocal cord function. Further studies were then conducted in 46 patients with difficult-to-treat asthma. MEASUREMENTS AND MAIN RESULTS: Vocal cord movement was quantified over the breathing cycle by CT using the ratio of vocal cord diameter to tracheal diameter. Normal limits were calculated, validated, and applied to evaluate difficult-to-treat asthma. Vocal cord movement was abnormal with excessive narrowing in 23 of 46 (50%) patients with asthma and severe in 9 (19%) patients (abnormal > 50% of inspiration or expiration time). Imaging also revealed that laryngeal dysfunction characterized the movement abnormality rather than isolated vocal cord dysfunction. CONCLUSIONS: Noninvasive quantification of laryngeal movement was achieved using CT larynx. Significant numbers of patients with difficult-to-treat asthma had excessive narrowing of the vocal cords. This new approach has identified frequent upper airway dysfunction in asthma with potential implications for disease control and treatment.

Venous air embolism in CT coronary angiography.

INTRODUCTION: Venous air embolization (VAE) from IV lines is a risk with IV contrast administration. The incidence of VAE ranges from 7% to 23%. While life-threatening VAE is rare, there is the potential risk of serious cerebrovascular events from paradoxical systemic air embolization (SAE) in patients with congenital intracardiac shunts. CT coronary angiogram (CTCA) hypothetically carries a higher risk of VAE as it requires dual injections as compared to single bolus dose contrast used in CT chest (CTC). The aim of this study was to assess the risk of VAE using CTCA as compared to conventional CTC. The incidence of cardiac shunts and their association with paradoxical SAE were also investigated. METHODS: A retrospective study was conducted at a tertiary hospital. Adult patients undergoing CTCA and CTC over a 6-month period in 2017 were included. Images were reviewed on PACS for the presence of VAE. Electronic medical records were interrogated for evidence of neurological sequelae or requiring neurological imaging (CTB/MRIB) within 1 month of the initial imaging. RESULTS: 508 patients were included, 408 underwent CTCA and 100 underwent CTC. The VAE incidence in CTCA was 24% (94 patients) and 10% in the CTC (10 patients). This was statistically significant. Among the CTCA group, 36% (108 patients) had an intracardiac shunt. No statistically significant difference in VAE incidence was identified in CTCA patients with shunts vs without shunts. There was no incidence of SAE in both groups. CONCLUSION: VAE is more common with CTCA than conventional CTC. There were no cases of paradoxical SAE found.

Acute chest pain investigation: utility of cardiac CT angiography in guiding troponin measurement.

PURPOSE: To assess the impact on length of stay and rate of major adverse cardiovascular events of a cardiac computed tomographic (CT) angiography-guided algorithm to examine patients who present to the emergency department (ED) with low- to intermediate-risk chest pain. MATERIALS AND METHODS: The study was approved by the institutional review board, and all patients gave written informed consent. Two hundred three consecutive patients (mean age, 55 years ± 11 [standard deviation]; 123 men) with low- to intermediate-risk ischemic-type chest pain were prospectively enrolled. Patients underwent initial cardiac CT angiography with subsequent treatment determined by reference to findings at cardiac CT angiography; patients without overt plaque were immediately discharged from the hospital, patients with nonobstructive plaque and mild-to-moderate stenoses were discharged after a negative 6-hour troponin level, and patients with severe stenoses were admitted to the hospital. Discharged patients were followed up for a mean of 14.2 months. Additionally, length of stay and safety outcomes among these patients were compared with those in 102 consecutive patients with low- to intermediate-risk chest pain who presented to the ED and underwent a standard of care (SOC) work-up without cardiac CT angiography. One-way analysis of variance with Bonferroni correction was used to compare length of stay between groups. RESULTS: Cardiac CT angiography findings in the 203 patients who underwent cardiac CT angiography were as follows: Sixty-five (32%) patients had no plaque, 107 (53%) had nonobstructive plaque, and 31 (15%) had severe stenoses. At follow-up, there were no deaths or cases of acute coronary syndrome (cardiac CT angiography, 0%, 95% confidence interval [CI]: 0%, 1.85%; SOC, 0%, 95% CI: 0%, 3.63%), and the rate of readmission to the hospital because of chest pain was higher with the SOC approach (9% vs 1%, P = .01). Mean ED length of stay was lower with cardiac CT angiography (6.62 hours ± 0.38 after a single troponin level and 9.15 hours ± 0.30 after serial troponin levels) than with the SOC approach (11.62 hours ± 0.47, P < .001). CONCLUSION: Tailoring troponin measurement to cardiac CT angiography findings is safe and allows early discharge of patients with low- to intermediate-risk chest pain, resulting in reduced length of stay.

Coronary image quality of 320-MDCT in patients with heart rates above 65 beats per minute: preliminary experience.

OBJECTIVE: High heart rate may negatively influence the image quality of cardiac CT. The technical advances of 320-MDCT may overcome issues with poor image quality associated with high heart rate. This study aimed to evaluate the coronary image quality of 320-MDCT in patients with heart rates above 65 beats/min. MATERIALS AND METHODS: Patients who presented for cardiac CT were divided into two groups according to heart rate, either greater than 65 beats/min or less than or equal to 65 beats/min. Two radiologists were blinded to the patient groups and evaluated images of 15 coronary artery segments per patient using 320-MDCT with consensus agreement. The image quality was scored subjectively as 1 or 2 (diagnostic quality) or 3 (poor quality and nondiagnostic). RESULTS: There were no statistically significant differences between the two groups in terms of age, sex, and body mass index (p > 0.05). The median heart rate was 70 beats/min (range, 67-110 beats/min) for the group with heart rate greater than 65 beats/min and 60 beats/min (range, 48-65 beats/min) for the group with heart rate less than or equal to 65 beats/min (p < 0.001). In patients with heart rates greater than 65 beats/min, diagnostic quality images (scores of 1 or 2) were obtained in 95.6% of the analyzed segments, compared with 96.9% in the group with heart rate less than or equal to 65 beats/min (p = 0.7). CONCLUSION: Our initial evaluation suggests that coronary artery images of diagnostic quality can be obtained using 320-MDCT in most patients with heart rates greater than 65 beats/min, in percentages similar to those for patients with heart rates less than or equal to 65 beats/min. This finding may be the result of the inherent image acquisition and reconstruction technique of 320-MDCT.

Comparison of 4 cm Z-axis and 16 cm Z-axis multidetector CT perfusion.

OBJECTIVE: The aim of the study was to compare 4 cm with 16 cm Z-axis coverage in the assessment of brain CT perfusion (CTP) using. 320 slice multidetector CT METHODS: A retrospective non-randomised review of CTP performed on MD320 CT between September 2008 and January 2009 was undertaken. Two experienced readers reviewed the studies along with the 4 cm and 16 cm Z-axis CTP image data set. The outcome parameters assessed were the extent of the original finding, any additional findings and a change of diagnosis. RESULTS: 14 out of 27 patients were found to have abnormal CTP (mean age 58.1 years, 9 male). The 16 cm Z-axis increased the accuracy of the infarct core in 78% and ischaemic penumbra quantification in 100% of the cases. It also diagnosed additional infarcts in the same vascular territory in 28% of cases and in a different vascular territory in 14%. CONCLUSIONS: The increased field of view with MD320 better defines the true extent of the infarct core and ischaemic penumbra. It also identified other areas of infarction that were not identified on the 4 cm Z-axis.

Image quality of coronary 320-MDCT in patients with atrial fibrillation: initial experience.

OBJECTIVE: Noninvasive coronary angiography has generally been contraindicated in patients with atrial fibrillation because of the difficulty in synchronizing an irregular heartbeat with table gantry movement. The objective of this study was to evaluate and compare the quality of 320-MDCT images obtained in patients with atrial fibrillation and in a control group of patients in sinus rhythm. MATERIALS AND METHODS: Two reviewers were blinded to the patient groups and evaluated images of 15 coronary artery segments for each patient using 320-MDCT. The images were printed on glossy paper and scored subjectively as 1 or 2, meaning of diagnostic quality, or 3, meaning poor quality. RESULTS: No statistical difference between the groups was noted in patient age: The mean age of the patients with atrial fibrillation was 67 years (age range, 52-82 years) and that of the patients in sinus rhythm was 59 years (36-86 years) (p = 0.3). Scores of 1 and 2 (diagnostic quality) were assigned to 100% in sinus rhythm and 96% in atrial fibrillation (p < 0.05). Scores of 3 were seen only in the atrial fibrillation group (7/175, 4%). Segment 15, the distal circumflex artery, was the segment that was most frequently assigned a score of 3 (2/7, 28.6%). A discrepancy in the two reviewers' scores was seen in 25 segments (7%), requiring joint consensus. The segments that most frequently required consensus reading were segments 12 and 15. The overall mean image quality score for all three coronary arteries in atrial fibrillation was 1.25 +/- 0.47 (SD) and 1.08 +/- 0.26 in sinus rhythm (p < 0.001). The median effective dose was 19.28 and 13.55 mSv in the atrial fibrillation and sinus rhythm groups, respectively. CONCLUSION: The analysis of our initial experience shows that imaging in patients with atrial fibrillation is possible using 320-MDCT, with images of most segments obtained being of diagnostic quality. Segment 15 was the most difficult to see on 320-MDCT because of the small caliber of the vessel; poor visualization of that segment mostly occurred in the setting of a dominant right coronary arterial system.

Diagnosis of vocal cord dysfunction in asthma with high resolution dynamic volume computerized tomography of the larynx.

BACKGROUND AND OBJECTIVE: Vocal cord dysfunction (VCD) often masquerades as asthma and reports have suggested that up to 30% of patients with asthma may have coexistent VCD. Diagnosis of VCD is difficult, in part because it involves laryngoscopy which has practical constraints, and there is need for rapid non-invasive diagnosis. High speed 320-slice volume CT demonstrates laryngeal function during inspiration and expiration and may be useful in suspected VCD. METHODS: Endoscopy and high resolution 320-slice dynamic volume CT were used to examine and compare laryngeal anatomy and movement in a case of subglottic stenosis and in a patient with confirmed VCD. Nine asthmatics with ongoing symptoms and suspected VCD also underwent 320-slice dynamic volume CT. Tracheal and laryngeal anatomy and movement were evaluated and luminal areas were measured. Reductions in vocal cord luminal area >40%, lasting for >70% duration of inspiration/expiration, were judged to be consistent with VCD. RESULTS: Studies of subglottic tracheal stenosis validated anatomical similarities between endoscopy and CT images. Endoscopy and 320-slice volume CT also provided comparable dynamic images in a patient with confirmed VCD. A further nine patients with a history of severe asthma and suspected VCD were studied using CT. Four patients had evidence of VCD and the median reduction of luminal area during expiration was 78.2% (range 48.2-92.5%) compared with 10.4% (range 4.7-30%) in the five patients without VCD. Patients with VCD had no distinguishing clinical characteristics. CONCLUSIONS: Dynamic volume CT provided explicit images of the larynx, distinguished function of the vocal cords during the respiratory cycle and could identify putative VCD. The technique will potentially provide a simple, non-invasive investigation to identify laryngeal dysfunction, permitting improved management of asthma.

Non-invasive CT-derived fractional flow reserve and static rest and stress CT myocardial perfusion imaging for detection of haemodynamically significant coronary stenosis.

Computed tomography derived fractional flow reserve (FFRCT) and computed tomography stress myocardial perfusion imaging (CTP) are techniques to assess haemodynamic significance of coronary stenosis. To compare the diagnostic performance of FFRCT and static rest/stress CTP in detecting fractional flow reserve (FFR) defined haemodynamically-significant stenosis (FFR ≤ 0.8). Fifty-one patients (96 vessels) with suspected coronary artery disease from a single institution planned for elective invasive-angiography prospectively underwent research indicated 320-detector-CT-coronary-angiography (CTA) and adenosine-stress CTP and invasive FFR. Analyses were performed in separate core-laboratories for FFRCT and CTP blinded to FFR results. Myocardial perfusion was assessed visually and semi-quantitatively by transmural perfusion ratio (TPR). Invasive FFR ≤ 0.8 was present in 33% of vessels and 49% of patients. FFRCT, visual CTP and TPR analysis was feasible in 96%, 92% and 92% of patients respectively. Overall per-vessel sensitivity, specificity and diagnostic accuracy for FFRCT were 81%, 85%, 84%, for visual CTP were 50%, 89%, 75% and for TPR were 69%, 48%, 56% respectively. Receiver-operating-characteristics curve analysis demonstrated larger per vessel area-under-curve (AUC) for FFRCT (0.89) compared with visual CTP (0.70; p < 0.001), TPR (0.58; p < 0.001) and CTA (0.70; p = 0.0007); AUC for CTA + FFRCT (0.91) was higher than CTA + visual CTP (0.77, p = 0.008) and CTA + TPR (0.74, p < 0.001). Per-patient AUC for FFRCT (0.90) was higher than visual CTP (0.69; p = 0.0016), TPR (0.56; p < 0.0001) and CTA (0.68; p = 0.001). Based on this selected cohort of patients FFRCT is superior to visually and semi-quantitatively assessed static rest/stress CTP in detecting haemodynamically-significant coronary stenosis as determined on invasive FFR.

Noninvasive CT-Derived FFR Based on Structural and Fluid Analysis: A Comparison With Invasive FFR for Detection of Functionally Significant Stenosis.

OBJECTIVES: This study describes the feasibility and accuracy of a novel computed tomography (CT) fractional flow reserve (FFR) technique based on alternative boundary conditions. BACKGROUND: Techniques used to compute FFR based on images acquired from coronary computed tomography angiography (CTA) are described. Boundary conditions were typically determined by allometric scaling laws and assumptions regarding microvascular resistance. Alternatively, boundary conditions can be derived from the structural deformation of coronary lumen and aorta, although its accuracy remains unknown. METHODS: Forty-two patients (78 vessels) in a single institution prospectively underwent 320-detector coronary CTA and FFR. Deformation of coronary cross-sectional lumen and aorta, computed from coronary CTA images acquired over diastole, was used to determine the boundary conditions based on hierarchical Bayes modeling. CT-FFR was derived using a reduced order model performed using a standard desktop computer and dedicated software. First, 12 patients (20 vessels) formed the derivation cohort to determine optimal CT-FFR threshold with which to detect functional stenosis, defined as FFR of ≤0.8, which was validated in the subsequent 30 patients (58 vessels). RESULTS: Derivation cohort results demonstrated optimal threshold for CT-FFR was 0.8 with 67% sensitivity and 91% specificity. In the validation cohort, CT-FFR was successfully computed in 56 of 58 vessels (97%). Compared with coronary CTA, CT-FFR at ≤0.8 demonstrated a higher specificity (87% vs. 74%, respectively) and positive predictive value (74% vs. 60%, respectively), with comparable sensitivity (78% vs. 79%, respectively), negative predictive value (89% vs. 88%, respectively), and accuracy (area under the curve: 0.88 vs. 0.77, respectively; p = 0.22). Based on Bland-Altman analysis, mean intraobserver and interobserver variability values for CT-FFR were, respectively, -0.02 ± 0.05 (95% limits of agreement: -0.12 to 0.08) and 0.03 ± 0.06 (95% limits: 0.07 to 0.19). Mean time per patient for CT-FFR analysis was 27.07 ± 7.54 min. CONCLUSIONS: CT-FFR based on alternative boundary conditions and reduced-order fluid model is feasible, highly reproducible, and may be accurate in detecting FFR ≤ 0.8. It requires a short processing time and can be completed at point-of-care. Further validation is required in large prospective multicenter settings.

Rest and stress transluminal attenuation gradient and contrast opacification difference for detection of hemodynamically significant stenoses in patients with suspected coronary artery disease.

This study evaluated the feasibility of stress 320 detector CT coronary angiography (CTA) derived transluminal attenuation gradient (TAG320) and contrast opacification (CO) difference to detect hemodynamically significant stenoses as determined by invasive fractional flow reserve (FFR ≤ 0.80). Twenty-seven patients, including 51 vessels on rest CTA were studied. 16 (31 %) vessels were not interpretable on stress CTA largely secondary to motion artefacts. Receiver operating characteristic curve analysis showed a comparable area under the curve (AUC) for rest and stress TAG320 (0.78 and 0.75) which was higher than CTA alone (0.68), and rest and stress CO difference (0.76 and 0.67). Compared with rest CTA, stress CTA demonstrated inferior image quality (Median Likert score 4 vs. 3, P < 0.0001) and required a higher mean radiation exposure (3.2 vs. 5.1 mSv, P < 0.0001). Stress TAG320 and CO difference is less feasible and was not superior in diagnostic performance when compared with rest TAG320 and CO difference.

Pre-procedural combined coronary angiography and stress myocardial perfusion imaging using 320-detector CT in unprotected left main and ostial left anterior descending artery intervention.

Pre-procedural anatomic and functional coronary assessment plays a crucial role in selection of patients suitable for unprotected left main percutaneous coronary intervention. Combined coronary computed tomography angiography and adenosine stress computed tomography myocardial perfusion imaging is a non-invasive technique which may provide this information. This is the first report describing its use to assist patient selection and procedural planning prior to elective left main and ostial left anterior descending artery coronary intervention.

Dynamic four-dimensional computed tomography for preoperative assessment of lung cancer invasion into adjacent structures†.

OBJECTIVES: The 320-slice computed tomography (CT) provides three-dimensional and dynamic imaging resulting in the ability to assess motion analysis between two adjacent structures (the fourth dimension). Differential movements between two adjacent structures would indicate that there is no fixation between the two structures. METHODS: Eight patients with non-small-cell lung cancers located adjacent to vital structures (e.g. the great vessels) (n = 4), mediastinum (n = 1) or chest wall (n = 3) where conventional CT was unable to exclude local invasion underwent dynamic four-dimensional (4D) CT assessment. In 3 patients, the lung tumour was abutting the chest wall and 1 patient had tumour abutting the mediastinum. The remaining patients included a patient with a large 14-cm left lower lobe cancer abutting the descending thoracic aorta who had previous pleurodesis; a patient with an apical right upper lobe 6-cm cancer with static imaging appearances suggestive of tumour invasion into the apex, the mediastinal surface and superior vena cava (SVC); a patient with a 3.5-cm cancer which had a broad 2.5-cm base abutting the distal aortic arch and a patient with a 14-cm left upper lobe cancer abutting the aortic arch, descending thoracic aorta and chest wall. Differential movements between the tumour and adjacent structure on 4D CT were considered indicative of the absence of frank invasion. RESULTS: Dynamic 4D imaging revealed differential movements between the tumour and the adjacent structures in 7 cases, suggesting the absence of overt malignant invasion. Intraoperative assessments confirmed the findings. In 1 case, a small area of fixation seen on dynamic CT corresponded intraoperatively to superficial invasion of the adventitia of the SVC. CONCLUSIONS: Dynamic 4D 320-slice CT is useful in the preoperative assessment of the direct invasion of lung cancer into adjacent structures and hence its resectability.

Dynamic 320-slice CT larynx for detection and management of idiopathic bilateral vocal cord paralysis.

Idiopathic bilateral vocal cord paralysis (VCP) is a rare and difficult condition often undiagnosed and frequently confused with asthma and other respiratory conditions. Accurate diagnosis is crucial since 80% of cases patients require surgical intervention, such as tracheostomy or laser surgery, to relieve symptoms. The "gold standard" for diagnosing VCP has been laryngoscopy. In this case study, we demonstrate for the first time that idiopathic bilateral VCP can be accurately diagnosed by means of a novel noninvasive methodology: dynamic volume 320-slice computed tomography larynx. Three-dimensional reconstruction of laryngeal motion during the breathing cycle permitted functional assessment of the larynx showing absence of vocal cord movements. The new methodology may be valuable for noninvasive diagnosis of vocal cord movement disorders before and for follow-up after surgery.

Comparison of diagnostic accuracy of combined assessment using adenosine stress computed tomography perfusion + computed tomography angiography with transluminal attenuation gradient + computed tomography angiography against invasive fractional flow reserve.

OBJECTIVES: The goal of this study was to compare the diagnostic accuracy of combined computed tomography perfusion (CTP) + computed tomography angiography (CTA), transluminal attenuation gradient by 320-detector row computed tomography (TAG320) + CTA, and CTP + TAG320 + CTA (multidetector computed tomography-integrated protocol [MDCT-IP]) assessment in predicting significant fractional flow reserve (FFR). BACKGROUND: CTA has limited specificity for predicting functionally significant stenoses. Novel CT techniques, including adenosine stress CTP and TAG320, may improve the diagnostic accuracy of CTA. METHODS: CTA, CTP, and TAG320 were assessed using 320-detector row MDCT. Patients who underwent CTA, CTP, and FFR assessment on invasive coronary angiography were included. CTP was assessed using the visual perfusion assessment. TAG320 was defined as the linear regression coefficient between luminal attenuation and axial distance. A TAG320 cutoff value of -15.1 HU/10 mm as previously described was defined as significant. Functionally significant coronary stenosis was defined as FFR ≤0.8. RESULTS: The cohort included 75 patients (age 64.1 ± 10.8 years, 52 men) and 44 (35%) FFR-significant vessels. In 127 vessels, CTA predicted FFR-significant stenosis with 89% sensitivity and 65% specificity compared with MDCT-IP, which showed 88% sensitivity and 83% specificity. In 97 vessels in which the results of all techniques were available, TAG320 + CTA (area under the curve [AUC] = 0.844) and CTP + CTA (AUC = 0.845) had comparable per-vessel diagnostic accuracy (p = 0.98). The diagnostic accuracy of MDCT-IP (AUC = 0.91) was superior to TAG320 + CTA or CTP + CTA (p = 0.01). CONCLUSIONS: In vessels without significant calcification or artefact, TAG320 + CTA and CTP + CTA provide comparable diagnostic accuracy for functional assessment of coronary artery stenosis. MDCT-IP may provide the best diagnostic accuracy for functional assessment of coronary artery stenosis.

Superior CT coronary angiography image quality at lower radiation exposure with second generation 320-detector row CT in patients with elevated heart rate: a comparison with first generation 320-detector row CT.

BACKGROUND: This study aims to compare the image quality of second generation versus first generation 320-computed tomography coronary angiography (CTCA) in patients with heart rate ≥65 bpm as it has not been specifically reported. METHODS: Consecutive patients who underwent CTCA using second-generation-320-detector-row-CT were prospectively enrolled. A total of 50 patients with elevated (≥65 bpm) heart rate and 50 patients with controlled (<65 bpm) heart rate were included. Age and gender matched patients who were scanned with the first-generation-320-detector-row-CT were retrospectively identified. Image quality in each coronary artery segment was assessed by two blinded CT angiographers using the five-point Likert scale. RESULTS: In the elevated heart rate cohorts, while there was no significant difference in heart rate during scan-acquisition (66 vs. 69 bpm, P=0.308), or body mass index (28.5 vs. 29.6, P=0.464), the second generation scanner was associated with better image quality (3.94±0.6 vs. 3.45±0.8, P=0.001), and with lower radiation (2.8 vs. 4.3 mSv, P=0.009). There was no difference in scan image quality for the controlled heart rate cohorts. CONCLUSIONS: The second generation CT scanner provides better image quality at lower radiation dose in patients with elevated heart rate (≥65 bpm) compared to first generation CT scanner.

Dynamic volumetric computed tomographic assessment of the young paediatric airway: Initial experience of rapid, non-invasive, four-dimensional technique.

INTRODUCTION: The aim of this study was to evaluate the dynamic volumetric CT in the assessment of the paediatric airway. METHODS: Ethics board approval was obtained for this retrospective review. Eight infants (median age 6 months, range 3 weeks to 1 year, 50% female) at a tertiary paediatric centre with complex clinical respiratory presentation underwent volumetric CT assessment of their airways. The entire lungs were examined over 1-2 respiratory cycles. In four patients, intravenous contrast was administered to assess for vascular airway compression. The patients were not intubated. CT findings were correlated with bronchography and bronchoscopy, where available. RESULTS: Two patients had diffuse tracheobronchomalacia associated with chronic lung disease. One patient demonstrated focal severe cervical tracheomalacia. One patient had a double aortic arch causing fixed narrowing with superimposed malacia of the distal trachea. Four patients had normal airways; one with chronic lung disease, one demonstrating air trapping. CT findings were concordant with bronchography (one case) and bronchoscopy (four cases) in all but one (CT negative, bronchoscopy positive) but did not alter patient management. CONCLUSION: The assessment of the paediatric airway, and in particular for tracheobronchomalacia, is difficult. Assessment with bronchography, bronchoscopy, helical CT and MR have issues with reliability, intubation, intratracheal/bronchial contrast administration and ionising radiation. Volumetric CT assesses the entire central airway in children at much lower radiation dose compared with previous dynamic CT imaging. This non-invasive, rapid assessment obviates the need for patient cooperation and enables evaluation of extratracheal intrathoracic structures. Volumetric CT enables four-dimensional assessment for paediatric tracheobronchomalacia without intubation or patient cooperation and at low radiation dose.