Improving hybrid image and structure-based deformable image registration for large internal deformations.

Objective.Deformable image registration (DIR) is a widely used technique in radiotherapy. Complex deformations, resulting from large anatomical changes, are a regular challenge. DIR algorithms generally seek a balance between capturing large deformations and preserving a smooth deformation vector field (DVF). We propose a novel structure-based term that can enhance the registration efficacy while ensuring a smooth DVF.Approach.The proposed novel similarity metric for controlling structures was introduced as a new term into a commercially available algorithm. Its performance was compared to the original algorithm using a dataset of 46 patients who received pelvic re-irradiation, many of which exhibited complex deformations.Main results.The mean Dice Similarity Coefficient (DSC) under the improved algorithm was 0.96, 0.94, 0.76, and 0.91 for bladder, rectum, colon, and bone respectively, compared to 0.69, 0.89, 0.62, and 0.88 for the original algorithm. The improvement was more pronounced for complex deformations.Significance.With this work, we have demonstrated that the proposed term is able to improve registration accuracy for complex cases while maintaining realistic deformations.

Positron emission tomography features of hidradenitis suppurativa.

A 35-year-old male with classical Hodgkin's lymphoma (nodular sclerosing, grade 1 histology, clinical stage 2A) underwent a positron emission tomography (PET) scan to assess response to treatment. Half body CT PET imaging was obtained using a Siemens Biograph scanner from eyes to thighs. 405 MBq of 18-fluorodeoxyglucose (FDG) was injected with acquisition starting at 60 min. There was unexpected intense focal uptake in the superficial subcutaneous tissues of the abdomen, pelvis and lateral chest wall with overlying skin thickening seen on the CT component. This was initially of concern, but the patient was known to have a history of hidradenitis suppurativa (HS). On further examination, the radiological abnormalities corresponded to the clinical sites of involvement. To the best of our knowledge, this is the first documentation of the appearance of HS on PET scan.

The importance of ultrasound in staging and gaining a pathological diagnosis in patients with lung cancer--a two year single centre experience.

BACKGROUND: Initial studies on the use of ultrasound in the detection and sampling of supraclavicular lymph nodes in patients with suspected lung cancer show this to be a promising technique, giving both a cytological diagnosis and pathological N3 (pN3) stage. Leicester published its initial experience in 2005 and the aim of this study was to establish if this had been embedded into the diagnostic pathway, and further to examine the use of ultrasound in diagnosing and staging lung cancer by imaging other areas including pleural effusions, chest wall, bone and liver lesions. METHODS: All patients diagnosed with lung cancer, registered on the Leicester lung cancer database over a two year period between January 2007 and December 2008, had their imaging and pathology retrospectively reviewed; 996 primary lung cancer patients were identified (n=996). Of these, 318 patients underwent an ultrasound examination (n=318), consisting of ultrasound of the neck, pleural cavity, and metastatic lesions potentially amenable to ultrasound guided aspiration/biopsy. RESULTS: The overall malignant yield was 45% of patients scanned (95% CI 39.5% to 50.4%) and 81.3% of patients sampled (95% CI 75.5% to 87%). Of the 996 patients, 14.4% (n=143) had a positive ultrasound guided cytological diagnosis (95% CI 12.2% to 16.5%). Of all the pathological diagnoses (n=765), 18.7% were ultrasound guided (95% CI 15.9% to 21.5%). In particular, 32.2% of patients with CT detected neck or mediastinal nodes had a diagnosis and stage achieved by neck ultrasound. CONCLUSION: The use of ultrasound gives a rapid and less invasive method of diagnosing and staging lung cancer and has become embedded into the diagnostic pathway. We advocate its increased use and availability in patients with lung cancer.

Multidetector CT imaging of pleura: comparison of two contrast infusion protocols.

OBJECTIVES: Imaging of the pleura by multidetector CT (MDCT) can be challenging. There is no clear evidence or guidelines on contrast infusion parameters for imaging pleura. We compared two contrast protocols for assessing pleural pathology on MDCT. METHODS: This was a prospective study in which consecutive patients with MDCT for suspected pleural disease on chest radiograph were randomised into two groups. The first group received 150 ml of intravenous contrast at a rate of 2.5 ml s(-1) and the second group received 100 ml at 2 ml s(-1). Images were acquired after a 60 s delay. Hounsfield units of the pleura, thoracic aorta, main pulmonary artery, portal vein and superior mesenteric artery were measured and analysed by two independent readers. RESULTS: 40 patients (20 in each group) who had pleural enhancement on MDCT were included for final analysis. The mean pleural enhancement value was 83 HU (Group A) vs 59 HU (Group B) (p = 0.0004). The mean aortic enhancement was 241 HU (A) vs 141 HU (B) (p<0.0001); main pulmonary artery enhancement was 208 HU (A) vs 139 HU (B) (p<0.0002); portal venous enhancement was 169 HU (A) vs 115 HU (B) (p<0.0001); and the superior mesenteric artery enhancement was 215 HU (A) vs 128 HU (B) (p<0.0001). CONCLUSION: Enhancement of the pleura and major vessels was significantly higher in the group receiving more contrast at a greater infusion rate. This technique of a single scan through the entire pleural surface with a delayed acquisition is promising. When pleural disease is suspected, contrast infusion protocols should be modified to achieve the best results and clinicians should be encouraged to specifically request a "pleural CT".

Management benefits and safety of computed tomography in patients undergoing extracorporeal membrane oxygenation therapy: experience of a single centre.

AIM: To evaluate the benefits and logistical safety of computed tomography (CT) imaging in patients undergoing extracorporeal membrane oxygenation (ECMO) therapy in a single institution. MATERIALS AND METHODS: Over a period of 25 months, 134 patients (80 neonates, 19 children, and 35 adults) underwent ECMO therapy at this institution. The imaging of these patients was reviewed to identify patients who had undergone CT imaging whilst on ECMO. Patient notes were retrospectively reviewed. CT findings and subsequent decisions were analysed to assess the benefit of CT imaging. Complications arising due to the logistics of performing the scan were analysed to assess the safety of performing CT in ECMO patients. RESULTS: Of 134 patients, 14 (10%) had a total of 15 CT examinations whilst undergoing ECMO therapy. Indications for CT included new neurology, increased respiratory demand, and increasing requirement for high ECMO flows. There were no major complications and two minor complications associated with the logistics of performing a CT examination on an ECMO patient. Significant findings resulted from 73.3% (11/15) of the CT examinations, and in all 15 examinations information was provided that was used in making further management decisions, including, in some cases, withdrawal of ECMO therapy. CONCLUSION: With an experienced team, CT imaging of patients on ECMO can be performed safely. CT provides valuable information for subsequent management of patients undergoing ECMO therapy.

Indications for thoracic ultrasound in chest medicine: an observational study.

INTRODUCTION: Thoracic ultrasound (TUS) is increasingly used in chest medicine in secondary care. The indications for TUS are well known but less is known about their relative frequency. The purpose of this observational study was to describe the common indications for TUS and their relative frequency and the impact of TUS on management in a consecutive group of patients. METHODS: 80 consecutive inpatients and outpatients referred for TUS by the same operator in a UK National Health Service teaching hospital were included. Demographic data, clinical indication, findings and effect of TUS on clinical management were noted. RESULTS: The most common clinical indication was to assess a pleural effusion in 60/80 cases (75%), but other indications included assessment of diaphragmatic function, pleural thickening and chest wall masses. TUS significantly altered patient management in 52/80 cases (65%): it resolved equivocal chest radiograph (CXR) findings and excluded pathology in 20/80 cases (25%), detected effusions not visible on CXR in 14/80 cases (18%), localised a safe site for medical thoracoscopy in 11/80 cases (14%) when not clinically apparent, and detected unexpected septation in 7/80 cases (9%). TUS guided pleural cytology diagnosed pleural fluid metastases in 9/22 cases aspirated (41%). CONCLUSION: There are many clinical indications for TUS but the most common is pleural effusion assessment. TUS can diagnose inoperable pleural metastases, allow safe day case pleural intervention, exclude significant pleural pathology not visible on CXR, and triage further investigation.

Airway wall geometry in asthma and nonasthmatic eosinophilic bronchitis.

BACKGROUND: Variable airflow obstruction and airway hyperresponsiveness (AHR) are features of asthma, which are absent in nonasthmatic eosinophilic bronchitis (EB). Airway remodelling is characteristic of both conditions suggesting that remodelling and airway dysfunction are disassociated, but whether the airway geometry differs between asthma and nonasthmatic EB is uncertain. METHODS: We assessed airway geometry by computed tomography (CT) imaging in asthma vs EB. A total of 12 subjects with mild-moderate asthma, 14 subjects with refractory asthma, 10 subjects with EB and 11 healthy volunteers were recruited. Subjects had a narrow collimation (0.75 mm) CT scan from the aortic arch to the carina to capture the right upper lobe apical segmental bronchus (RB1). In subjects with asthma and EB, CT scans were performed before and after a 2-week course of oral prednisolone (0.5 mg/kg). RESULTS: Mild-moderate and refractory asthma were associated with RB1 wall thickening in contrast to subjects with nonasthmatic EB who had maintained RB1 patency without wall thickening [mean (SD) % wall area and luminal area mild-t0-moderate asthma 67.7 (7.3)% and 6.6 (2.8) mm(2)/m(2), refractory asthma 67.3 (5.6)% and 6.7 (3.4) mm(2)/m(2), healthy control group 59.7 (6.3)% and 8.7 (3.8) mm(2)/m(2), EB 61.4 (7.8)% and 11.1 (4.6) mm(2)/m(2) respectively; P < 0.05]. Airway wall thickening of non-RB1 airways generation three to six was a feature of asthma only. There was no change in airway geometry of RB1 after prednisolone. Proximal airway wall thickening was associated with AHR in asthma (r = -0.56; P = 0.02). CONCLUSIONS: Maintained airway patency in EB may protect against the development of AHR, whereas airway wall thickening may promote AHR in asthma.

The early use of PET-CT alters the management of patients with esophageal cancer.

INTRODUCTION: The routine use of positron emission tomography-computed tomography (PET-CT) in the staging of patients with esophageal carcinoma remains contentious, with conflicting reports of its benefit. In our unit, PET-CT has been used routinely in the staging of all patients considered for radical therapy (surgery or chemoradiotherapy). Our aim was to determine the frequency with which PET-CT influenced decision making in the management of patients with carcinoma of the esophagus or gastroesophageal junction. METHODS: CT, PET-CT, and outcome information were collected on 38 patients considered for radical therapy. Patient proformas, with and without PET-CT findings, were constructed and each independently reviewed in a randomized and blinded fashion by five multidisciplinary team members (three surgeons, two oncologists) and a treatment strategy determined. RESULTS: PET-CT changed the staging for ten patients (26%). This translated into a change in management decision for seven patients (18%). The concordance between individual management plans and treatment intent was 79% for CT (150 of 190 decisions) and it was 92% for PET-CT (175 of 190 decisions). Full concordance between multidisciplinary team members was 66% with CT staging and 74% with the addition of PET-CT. CONCLUSION: The use of PET-CT early in the staging algorithm for esophageal carcinoma altered the staging for a quarter of patients and the management for a fifth of patients, supporting its inclusion early in the staging algorithm.

Pseudocalcification on chest CT scan.

Liquid ventilation with perfluorocarbons is used in severe respiratory failure that cannot be managed by conventional methods. Very little is known about the use of liquid ventilation in paediatric patients with respiratory failure and there are no reports describing the distribution and excretion of perfluorocarbons in paediatric patients with severe respiratory failure. The aim of this report is to highlight the prolonged retention of perfluorocarbons in a paediatric patient, mimicking pulmonary calcification and misleading the interpretation of the chest CT scan. A 10-year-old girl was admitted to our intensive care unit with severe respiratory failure due to miliary tuberculosis. Extracorporeal membrane oxygenation (ECMO) was used to support gas exchange and partial liquid ventilation (PLV) with perfluorodecalin was used to aid in oxygenation, lavage the lungs and clear thick secretions. The patient developed a pneumothorax (fluorothorax) on the next day and PLV was discontinued. Multiple bronchoalveolar lavages were performed to clear thick secretions. With no improvement in lung function over the next month a CT scan of the chest was performed. This revealed extensive pulmonary fibrosis and multiple high attenuation lesions suggestive of pulmonary calcification. To exclude perfluorodecalin as the cause for high attenuation lesions, a sample of perfluorodecalin was scanned to estimate the Hounsfield unit density, which was similar to the density of high attenuation lesions on chest CT scan. High-density opacification should be interpreted with caution, especially following liquid ventilation.

Image-guided pleural biopsy: diagnostic yield and complications.

BACKGROUND: Pleural biopsy and cytology are standard procedures for the investigation of pleural disease. Recent medical literature has suggested that image-guided pleural biopsy shows improved sensitivity for the diagnosis of pleural malignancy, when compared with the more commonly performed reverse bevel needle biopsy such as Abrams' needle. In our centre there has been an increasing trend towards performing image-guided pleural biopsies, and to our knowledge there is no large published series documenting the complication rate and diagnostic yield. METHODS: The radiology and pathology databases were searched for all image-guided [computed tomography (CT) and ultrasound (US)] pleural biopsies from January 2001 to December 2004. All imaging and histology were reviewed, and final diagnostic information about patients was obtained from the respiratory multidisciplinary team database and patient notes. A record was made of complications following biopsy, presence of pleura in the biopsy, and adequacy of tissue for histological diagnosis. RESULTS: A total of 82 patients underwent 85 image-guided pleural biopsies over a 4-year period. 80 cases were performed under CT and five under US guidance. The rate of new pneumothorax detected by chest radiography was 4.7%. No patient required a chest drain or blood transfusion to treat complications. In 10 (12%) cases, there was inadequate tissue to reach a confident histological diagnosis and in eight (9%) of these, no pleura was present. Assuming all suspicious and inadequate biopsies are treated as benign, which is the worst case scenario, image-guided pleural biopsy has a sensitivity and specificity of 76% and 100%, respectively, for the diagnosis of malignant disease. CONCLUSIONS: Image-guided pleural biopsy is a safe procedure with few associated complications and has a higher sensitivity than previously published series for reverse cutting needle biopsy in the diagnosis of malignant pleural disease.

Use of imaging in the management of malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is an increasingly prevalent tumour. The death rate associated with MPM is predicted to peak in the next 10 years, although radiologists and clinicians will be encountering cases for the next few decades. Contrast-enhanced CT is an established technique for evaluating suspected malignant pleural disease, but MPM can be reliably diagnosed only by histological sampling. However, even with adequate sampling and the use of immunocytochemistry, histological diagnosis is known to be difficult; definitive diagnosis may involve a combination of clinical presentation, radiological and histological appearances. Percutaneous biopsy is a promising technique for sampling the pleura. In view of its pattern of growth, MPM is a challenging disease to image by any method, and it behaves quite differently from lung cancer. This review aims to highlight the practical aspects of assessing malignant pleural mesothelioma.

The metabolic profile of azimilide in man: in vivo and in vitro evaluations.

The metabolic fate of azimilide in man is unusual as it undergoes a cleavage in vivo resulting in the formation of two classes of structurally distinct metabolites. During a metabolite profiling study conducted in human volunteers to assess the contribution of all pathways to the clearance of (14)C-azimilide, greater than 82% of radioactivity was recovered in urine (49%-58%) and feces (33%). Urine, feces, and plasma were profiled for metabolites. A cleaved metabolite, 4-chloro-2-phenyl furoic acid was present at high concentration in plasma (metabolite/parent AUC ratio approx. 4), while other plasma metabolites, azimilide N-oxide (metabolite/parent AUC ratio 0.001), and a cleaved hydantoin metabolite (metabolite/parent AUC ratio = 0.3) were present at lower concentrations than azimilide. In urine, the cleaved metabolites were the major metabolites, (> 35% of the dose) along with phenols (as conjugates, 7%-8%), azimilide N-oxide (4%-10%), a butanoic acid metabolite (2%-3%), and desmethyl azimilide (2%). A limited investigation of fecal metabolites indicated that azimilide (3%-5%), desmethyl azimilide (1%-3%), and the butanoic acid metabolite (< 1%) were present. Contributing pathways for metabolism of azimilide, identified through in vitro and in-vivo studies, were CYPs 1A1 (est. 28%), 3A4/5 (est. 20%), 2D6 (< 1%), FMO (est. 14%), and cleavage (35%). Enzyme(s) involved in the cleavage of azimilide were not identified.