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Backgrounds/aims: Locally advanced gallbladder cancer (GBC) is associated with survival limited to a few months. Extended resections (ER) are occasionally performed in this group and outcomes remain inconclusive. This study assessed outcomes after ER for locally advanced GBC., Methods: Patients who underwent ER for GBC between 2011 and 2020 were reviewed. ER was defined as a major hepatectomy alone (n = 9), a pancreaticoduodenectomy (PD) with or without minor hepatectomy (n = 3), a major hepatectomy with PD (HPD) (n = 3) or vascular resection and reconstruction (n = 4). We assessed 30-day morbidity, mortality, and 2-year overall survival (OS)., Results: Among 19 patients, negative margins were achieved in 14 (73.6%). The 30-day mortality was 1/9 (11.1%) for a major hepatectomy, 0/3 (0%) for a minor HPD, 2/3 (66.7%) for a major HPD, and 1/4 (25.0%) for vascular resection. All short term survivors (< 6 months) (n=8) had preoperative jaundice and 6/8 (75.0%) underwent a major HPD or vascular resection. There were five (26.3%) long term survivors. The median OS in patients with and without preoperative jaundice was 4.1 months (0.7-11.1 months) and 13.7 months (12-30.4 months), respectively ( p = 0.009) (2-year OS = 7% vs. 75%; p = 0.008). The median OS in patients who underwent a major hepatectomy alone or a minor HPD was 11.3 months (6.8-17.3 months) versus 1.4 months (0.3-4.1 months) ( p = 0.02) in patients who underwent major HPD or vascular resection (2 year OS = 33% vs. not reached) ( p = 0.010) respectively., Conclusions: In selected patients with GBC, when ER is limited to a major hepatectomy alone, or a minor HPD, acceptable survival can be achieved.

Background: Solitary pulmonary nodules (SPNs) measuring 8 to 30 mm in diameter require further workup to determine the likelihood of malignancy., Research Question: What is the diagnostic performance of a lung cancer prediction convolutional neural network (LCP-CNN) in SPNs using unenhanced and contrast-enhanced CT imaging compared with the current clinical workup?, Study Design and Methods: This was a post hoc analysis of the Single Pulmonary Nodule Investigation: Accuracy and Cost-Effectiveness of Dynamic Contrast Enhanced Computed Tomography in the Characterisation of Solitary Pulmonary Nodules trial, a prospective multicenter study comparing the diagnostic accuracy of dynamic contrast-enhanced (DCE) CT imaging with PET imaging in SPNs. The LCP-CNN was designed and validated in an external cohort. LCP-CNN-generated risk scores were created from the noncontrast and contrast-enhanced CT scan images from the DCE CT imaging. The gold standard was histologic analysis or 2 years of follow-up. The area under the receiver operating characteristic curves (AUC) were calculated using LCP-CNN score, maximum standardized uptake value, and DCE CT scan maximum enhancement and were compared using the DeLong test., Results: Two hundred seventy participants (mean ± SD age, 68.3 ± 8.8 years; 49% women) underwent PET with CT scan imaging and DCE CT imaging with CT scan data available centrally for LCP-CNN analysis. The accuracy of the LCP-CNN on the noncontrast images (AUC, 0.83; 95% CI, 0.79-0.88) was superior to that of DCE CT imaging (AUC, 0.76; 95% CI, 0.69-0.82; P = .03) and equal to that of PET with CT scan imaging (AUC, 0.86; 95% CI, 0.81-0.90; P = .35). The presence of contrast resulted in a small reduction in diagnostic accuracy, with the AUC falling from 0.83 (95% CI, 0.79-0.88) on the noncontrast images to 0.80 to 0.83 after contrast (P < .05 for 240 s after contrast only)., Interpretation: An LCP-CNN algorithm provides an AUC equivalent to PET with CT scan imaging in the diagnosis of solitary pulmonary nodules., Trial Registration: ClinicalTrials.gov Identifier; No.: NCT02013063., (Copyright © 2022 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Introduction: Dynamic contrast-enhanced CT (DCE-CT) and positron emission tomography/CT (PET/CT) have a high reported accuracy for the diagnosis of malignancy in solitary pulmonary nodules (SPNs). The aim of this study was to compare the accuracy and cost-effectiveness of these., Methods: In this prospective multicentre trial, 380 participants with an SPN (8-30 mm) and no recent history of malignancy underwent DCE-CT and PET/CT. All patients underwent either biopsy with histological diagnosis or completed CT follow-up. Primary outcome measures were sensitivity, specificity and overall diagnostic accuracy for PET/CT and DCE-CT. Costs and cost-effectiveness were estimated from a healthcare provider perspective using a decision-model., Results: 312 participants (47% female, 68.1±9.0 years) completed the study, with 61% rate of malignancy at 2 years. The sensitivity, specificity, positive predictive value and negative predictive values for DCE-CT were 95.3% (95% CI 91.3 to 97.5), 29.8% (95% CI 22.3 to 38.4), 68.2% (95% CI 62.4% to 73.5%) and 80.0% (95% CI 66.2 to 89.1), respectively, and for PET/CT were 79.1% (95% CI 72.7 to 84.2), 81.8% (95% CI 74.0 to 87.7), 87.3% (95% CI 81.5 to 91.5) and 71.2% (95% CI 63.2 to 78.1). The area under the receiver operator characteristic curve (AUROC) for DCE-CT and PET/CT was 0.62 (95% CI 0.58 to 0.67) and 0.80 (95% CI 0.76 to 0.85), respectively (p<0.001). Combined results significantly increased diagnostic accuracy over PET/CT alone (AUROC=0.90 (95% CI 0.86 to 0.93), p<0.001). DCE-CT was preferred when the willingness to pay per incremental cost per correctly treated malignancy was below £9000. Above £15 500 a combined approach was preferred., Conclusions: PET/CT has a superior diagnostic accuracy to DCE-CT for the diagnosis of SPNs. Combining both techniques improves the diagnostic accuracy over either test alone and could be cost-effective., Trial Registration Number: NCT02013063., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Current pathways recommend positron emission tomography-computerised tomography for the characterisation of solitary pulmonary nodules. Dynamic contrast-enhanced computerised tomography may be a more cost-effective approach., Objectives: To determine the diagnostic performances of dynamic contrast-enhanced computerised tomography and positron emission tomography-computerised tomography in the NHS for solitary pulmonary nodules. Systematic reviews and a health economic evaluation contributed to the decision-analytic modelling to assess the likely costs and health outcomes resulting from incorporation of dynamic contrast-enhanced computerised tomography into management strategies., Design: Multicentre comparative accuracy trial., Setting: Secondary or tertiary outpatient settings at 16 hospitals in the UK., Participants: Participants with solitary pulmonary nodules of ≥ 8 mm and of ≤ 30 mm in size with no malignancy in the previous 2 years were included., Interventions: Baseline positron emission tomography-computerised tomography and dynamic contrast-enhanced computer tomography with 2 years' follow-up., Main Outcome Measures: Primary outcome measures were sensitivity, specificity and diagnostic accuracy for positron emission tomography-computerised tomography and dynamic contrast-enhanced computerised tomography. Incremental cost-effectiveness ratios compared management strategies that used dynamic contrast-enhanced computerised tomography with management strategies that did not use dynamic contrast-enhanced computerised tomography., Results: A total of 380 patients were recruited (median age 69 years). Of 312 patients with matched dynamic contrast-enhanced computer tomography and positron emission tomography-computerised tomography examinations, 191 (61%) were cancer patients. The sensitivity, specificity and diagnostic accuracy for positron emission tomography-computerised tomography and dynamic contrast-enhanced computer tomography were 72.8% (95% confidence interval 66.1% to 78.6%), 81.8% (95% confidence interval 74.0% to 87.7%), 76.3% (95% confidence interval 71.3% to 80.7%) and 95.3% (95% confidence interval 91.3% to 97.5%), 29.8% (95% confidence interval 22.3% to 38.4%) and 69.9% (95% confidence interval 64.6% to 74.7%), respectively. Exploratory modelling showed that maximum standardised uptake values had the best diagnostic accuracy, with an area under the curve of 0.87, which increased to 0.90 if combined with dynamic contrast-enhanced computerised tomography peak enhancement. The economic analysis showed that, over 24 months, dynamic contrast-enhanced computerised tomography was less costly (£3305, 95% confidence interval £2952 to £3746) than positron emission tomography-computerised tomography (£4013, 95% confidence interval £3673 to £4498) or a strategy combining the two tests (£4058, 95% confidence interval £3702 to £4547). Positron emission tomography-computerised tomography led to more patients with malignant nodules being correctly managed, 0.44 on average (95% confidence interval 0.39 to 0.49), compared with 0.40 (95% confidence interval 0.35 to 0.45); using both tests further increased this (0.47, 95% confidence interval 0.42 to 0.51)., Limitations: The high prevalence of malignancy in nodules observed in this trial, compared with that observed in nodules identified within screening programmes, limits the generalisation of the current results to nodules identified by screening., Conclusions: Findings from this research indicate that positron emission tomography-computerised tomography is more accurate than dynamic contrast-enhanced computerised tomography for the characterisation of solitary pulmonary nodules. A combination of maximum standardised uptake value and peak enhancement had the highest accuracy with a small increase in costs. Findings from this research also indicate that a combined positron emission tomography-dynamic contrast-enhanced computerised tomography approach with a slightly higher willingness to pay to avoid missing small cancers or to avoid a 'watch and wait' policy may be an approach to consider., Future Work: Integration of the dynamic contrast-enhanced component into the positron emission tomography-computerised tomography examination and the feasibility of dynamic contrast-enhanced computerised tomography at lung screening for the characterisation of solitary pulmonary nodules should be explored, together with a lower radiation dose protocol., Study Registration: This study is registered as PROSPERO CRD42018112215 and CRD42019124299, and the trial is registered as ISRCTN30784948 and ClinicalTrials.gov NCT02013063., Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment ; Vol. 26, No. 17. See the NIHR Journals Library website for further project information.

Purpose: To compare qualitative and semi-quantitative PET/CT criteria, and the impact of nodule size on the diagnosis of solitary pulmonary nodules in a prospective multicentre trial., Methods: Patients with an SPN on CT ≥ 8 and ≤ 30 mm were recruited to the SPUTNIK trial at 16 sites accredited by the UK PET Core Lab. Qualitative assessment used a five-point ordinal PET-grade compared to the mediastinal blood pool, and a combined PET/CT grade using the CT features. Semi-quantitative measures included SUVmax of the nodule, and as an uptake ratio to the mediastinal blood pool (SUR BLOOD ) or liver (SUR LIVER ). The endpoints were diagnosis of lung cancer via biopsy/histology or completion of 2-year follow-up. Impact of nodule size was analysed by comparison between nodule size tertiles., Results: Three hundred fifty-five participants completed PET/CT and 2-year follow-up, with 59% (209/355) malignant nodules. The AUCs of the three techniques were SUVmax 0.87 (95% CI 0.83;0.91); SUR BLOOD 0.87 (95% CI 0.83; 0.91, p = 0.30 versus SUVmax); and SUR LIVER 0.87 (95% CI 0.83; 0.91, p = 0.09 vs. SUVmax). The AUCs for all techniques remained stable across size tertiles (p > 0.1 for difference), although the optimal diagnostic threshold varied by size. For nodules < 12 mm, an SUVmax of 1.75 or visual uptake equal to the mediastinum yielded the highest accuracy. For nodules > 16 mm, an SUVmax ≥ 3.6 or visual PET uptake greater than the mediastinum was the most accurate., Conclusion: In this multicentre trial, SUVmax was the most accurate technique for the diagnosis of solitary pulmonary nodules. Diagnostic thresholds should be altered according to nodule size., Trial Registration: ISRCTN - ISRCTN30784948. ClinicalTrials.gov - NCT02013063.

Competing Interests: There are no conflicts of interests.

Introduction: A systematic review and meta-analysis were performed to determine the diagnostic performance of dynamic contrast-enhanced computed tomography (DCE-CT) for the differentiation between malignant and benign pulmonary nodules., Methods: Ovid MEDLINE and EMBASE were searched for studies published up to October 2018 on the diagnostic accuracy of DCE-CT for the characterisation of pulmonary nodules. For the index test, studies with a minimum of a pre- and post-contrast computed tomography scan were evaluated. Studies with a reference standard of biopsy for malignancy, and biopsy or 2-year follow-up for benign disease were included. Study bias was assessed using QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies). The sensitivities, specificities, and diagnostic odds ratios were determined along with 95% confidence intervals (CIs) using a bivariate random effects model., Results: Twenty-three studies were included, including 2397 study participants with 2514 nodules of which 55.3% were malignant (1389/2514). The pooled accuracy results were sensitivity 94.8% (95% CI 91.5; 96.9), specificity 75.5% (69.4; 80.6), and diagnostic odds ratio 56.6 (24.2-88.9). QUADAS 2 assessment showed intermediate/high risk of bias in a large proportion of the studies (52-78% across the domains). No difference was present in sensitivity or specificity between subgroups when studies were split based on CT technique, sample size, nodule size, or publication date., Conclusion: DCE-CT has a high diagnostic accuracy for the diagnosis of pulmonary nodules although study quality was indeterminate in a large number of cases., Key Points: • The pooled accuracy results were sensitivity 95.1% and specificity 73.8% although individual studies showed wide ranges of values. • This is comparable to the results of previous meta-analyses of PET/CT (positron emission tomography/computed tomography) diagnostic accuracy for the diagnosis of solitary pulmonary nodules. • Robust direct comparative accuracy and cost-effectiveness studies are warranted to determine the optimal use of DCE-CT and PET/CT in the diagnosis of SPNs.

Introduction: Solitary pulmonary nodules (SPNs) are common on CT. The most cost-effective investigation algorithm is still to be determined. Dynamic contrast-enhanced CT (DCE-CT) is an established diagnostic test not widely available in the UK currently., Methods and Analysis: The SPUtNIk study will assess the diagnostic accuracy, clinical utility and cost-effectiveness of DCE-CT, alongside the current CT and 18-flurodeoxyglucose-positron emission tomography) ( 18 FDG-PET)-CT nodule characterisation strategies in the National Health Service (NHS). Image acquisition and data analysis for 18 FDG-PET-CT and DCE-CT will follow a standardised protocol with central review of 10% to ensure quality assurance. Decision analytic modelling will assess the likely costs and health outcomes resulting from incorporation of DCE-CT into management strategies for patients with SPNs., Ethics and Dissemination: Approval has been granted by the South West Research Ethics Committee. Ethics reference number 12/SW/0206. The results of the trial will be presented at national and international meetings and published in an Health Technology Assessment (HTA) Monograph and in peer-reviewed journals., Trial Registration Number: ISRCTN30784948; Pre-results., Competing Interests: Conflicts of Interest: None declared.

Incidental indeterminate solitary pulmonary nodules (SPN) that measure less than 3 cm in size are an increasingly common finding on computed tomography (CT) worldwide. Once identified there are a number of imaging strategies that can be performed to help with nodule characterization. These include interval CT, dynamic contrast enhanced computed tomography (DCE-CT), (18)F-fluorodeoxyglucose positron emission tomography-computed tomography ((18)F-FDG-PET-CT). To date the most cost effective and efficient non-invasive test or combination of tests for optimal nodule characterization has yet to be determined.DCE-CT is a functional test that involves the acquisition of a dynamic series of images of a nodule before and following the administration of intravenous iodinated contrast medium. This article provides an overview of the current indications and limitations of DCE- CT in nodule characterization and a systematic approach to how to perform, analyse and interpret a DCE-CT scan.

Chewing habits of tobacco, betel quid (paan), and betel nut (chhaliya) are common traditions in Pakistan. Different other preparations and combination of flavors with tobacco, paan, and chhaliya ingredients are commonly available in the market and have received considerable attention as sources of carcinogens that promote OSCC. Mutagens can damage DNA and generate promutagenic lesions. The germ line mutation/polymorphism of p53 gene has been reported to be involved in multiple steps of carcinogenesis. This study aims to find out the loss of TP53 functions due to mutation/polymorphism caused by genomic alteration and interaction with tobacco-related ingredients.Tissue and blood specimens from 260 OSCC patients were collected and compared with blood samples of 260 age- and sex-matched controls. Mutations in exons 2-11 of p53 gene were examined by PCR-SSCP and directly sequenced.A novel mutation was found in exon 7 of p53 gene. This mutation was observed in the tumors of the OSCC patients. The blood samples of the patients and the controls did not show the nucleotide change in this region. The "AGT" to "ACT" missense mutation was identified at position 719 at TP53. This results in the substitution of amino acid serine with threonine at codon 240 of p53 protein.This novel missence mutation in the DNA-binding domain indicated that the DNA structure may be damaged by the use of exogenous DNA-damaging agents, including tobacco-related carcinogens present in gutka, niswar, and manpuri, which may result in the loss of p53 protein function.

With the advent of multi-detector computed tomography, the identification of solitary pulmonary nodules is becoming ever more common. Although the prevalence of malignancy in a high risk population is only 1-1.5%, accurate identification of malignant nodules is essential to allow optimal treatment. In this article we review the most common causes of solitary pulmonary nodules and discuss diagnostic algorithms as well as some of the novel diagnostic imaging techniques in development.

Objectives: The chewing habit of paan, chhaliya, and tobacco is common in the traditional culture of Pakistan. Currently, niswar, gutka and manpuri are also commercially available in the Pakistani market. Epidemiologic evidences and increased rate of oral squamous cell carcinoma (OSCC) cases may indicate a direct relationship of these chewing habits with oral carcinogenesis. The p53 gene has been known to be a tumor suppressor gene that is found mutated in common human cancers. The p53 gene contains a single nucleotide polymorphism at codon 72 of exon 4 which encodes either proline (Pro) or arginine (Arg). The aim of the present study was to investigate association of p53 gene codon 72 polymorphism with patients of oral squamous cell carcinoma consuming these carcinogenic chewable materials., Materials and Methods: Blood and tissue samples of 260 OSCC patients were collected with informed consent from the local hospitals of Karachi. The patients were compared with controls of similar age and sex. The exon 4 of p53 gene was examined by PCR-SSCP. The tumor samples showing mobility shift were purified and sequenced., Results: The C>G missense mutation at nucleotide position 215 of the coding sequence was identified which substitutes proline with arginine at codon 72 of p53 protein. When the data for CCC72CGC polymorphism was analyzed statistically, a significant difference was observed between OSCC and control samples. The Pro allelic frequencies were significantly higher in OSCC patients as compare to controls. The current study indicated the Pro form of p53 codon 72 increases the risk of developing OSCC in Pakistani population. The risk ratio for Pro allele was 1.5004 (95% confidence interval: 1.2559 to 1.7924) and odds ratio of Pro allele was 2.389 (95% confidence interval: 1.5591 to 2.8137) in comparison with the Arg and Pro alleles in the OSCC group., Conclusion: These evidences suggest that there may be specific genetic targets with these chewing ingredients that are responsible for causing OSCC. The p53 codon 72 polymorphism is associated with OSCC at somatic cell level but the polymorphism was not associated at inherited level., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

We proposed to assess the feasibility of low mechanical index (MI) contrast enhanced ultrasound (CEUS) in the characterisation of thoracic lesions. Fifty patients were prospectively examined by CEUS and images acquired on a low MI (0.17-0.24) setting following injection of SonoVue. From region-of-interest (ROI) generated signal intensity (SI) time curves, the maximum SI, bolus arrival time (BAT), time to peak intensity (TTP), wash-in slope and mean transit time (MTT) were calculated. Using the Wilcoxon rank test; parameters and threshold values for positive differentiation were determined. In addition, for the parameters that allowed positive differentiation between malignant and benign lesions receiver operator curves (ROC) were obtained. The wash-in slope, TTP and MTT (p = 0.0003, <0.0001, 0.02) allowed positive differentiation. The sensitivity and specificity was 93% and 78%, with 6.87 s(-1) threshold value for the wash-in slope, 78% and 89% with 11.84 s threshold for the TTP and 48% and 89% with 78.6 s threshold for the MTT. CEUS is a useful tool for differentiating malignant and benign thoracic lesions., (Copyright © 2011 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Objective: To establish the presence and quantify Ethanol in commercially available mouthwashes., Methods: Samples from twelve commercially available mouthwashes were tested for the presence of Ethanol followed by the estimation of percentage of Ethanol in five brands in Pakistan Council of Scientific and Industrial Research (P.C.S.I.R) and Husein Ebrahim Jamal (H.E.J.) labs, Karachi., Results: Ten out of twelve brands of mouthwashes were found to be Ethanol positive., Conclusion: Alcohol (Ethanol) in the mouthwashes does not contribute to any therapeutic action. It is alarming to find the presence of alcohol in the mouthwashes which claim to contain no alcohol.

Background: Malignant pleural effusion (MPE) is a common clinical problem with described investigation pathways. While thoracic ultrasound (TUS) has been shown to be accurate in pleural fluid detection, its use in the diagnosis of malignant pleural disease has not been assessed. A study was undertaken to assess the diagnostic accuracy of TUS in differentiating malignant and benign pleural disease., Methods: 52 consecutive patients with suspected MPE underwent TUS and contrast-enhanced CT (CECT). TUS was used to assess pleural surfaces using previously published CT imaging criteria for malignancy, diaphragmatic thickness/nodularity, effusion size/nature and presence of hepatic metastasis (in right-sided effusions). A TUS diagnosis of malignant or benign disease was made blind to clinical data/other investigations by a second blinded operator using anonymised TUS video clips. The TUS diagnosis was compared with the definitive clinical diagnosis and in addition to the diagnosis found at CECT., Results: A definitive malignant diagnosis was based on histocytology (30/33; 91%) and clinical/CT follow-up (3/33; 9%). Benign diagnoses were based on negative histocytology and follow-up over 12 months in 19/19 patients. TUS correctly diagnosed malignancy in 26/33 patients (sensitivity 73%, specificity 100%, positive predictive value 100%, negative predictive value 79%) and benign disease in 19/19. Pleural thickening >1 cm, pleural nodularity and diaphragmatic thickening >7 mm were highly suggestive of malignant disease., Conclusion: TUS is useful in differentiating malignant from benign pleural disease in patients presenting with suspected MPE and may become an important adjunct in the diagnostic pathway.

Avian influenza is caused by the H5N1 subtype of the influenza A virus. Human transmission is either directly through close contact with infected birds usually poultry or their secretions. To date 178 people throughout South East Asia have been infected with 85 deaths. Patients usually present with a rapidly progressive pneumonia that can result in respiratory failure and acute respiratory distress syndrome. The chest radiograph therefore remains the most convenient and accessible imaging modality. Studies have shown that most radiographs are abnormal at the time of presentation with multifocal consolidation the commonest radiographic finding. During the course of disease, pleural effusions and cavitation can also develop. Consolidation that involves > or = 4 zones on presentation or at day 7 after the onset of symptoms and subsequent development of acute respiratory distress syndrome are generally associated with an adverse outcome. Chest CT examinations performed during the convalescent period have demonstrated persistent ground glass attenuation and segmental consolidation. Additional features included pseudocavitation, pneumatocoele formation, lymphadenopathy, and centrilobular nodules. Overall the appearances are suggestive of mild fibrosis.

Imaging plays an important role in the diagnosis and subsequent management of patients with pleural disease. The presence of a pleural abnormality is usually suggested following a routine chest x-ray, with a number of imaging modalities available for further characterization. This article describes the radiographic and cross-sectional appearances of pleural diseases, which are commonly encountered in every day practice. The conditions covered include benign and malignant pleural thickening, pleural effusions, empyema and pneumothoraces. The relative merits of CT, MRI and PET in the assessment of these conditions and the role of image-guided intervention are discussed.

Patients with unstable coronary syndromes are more likely to have a lesion containing thrombus and have a higher procedural complication and restenosis rate. The aim of this study was to evaluate the effect of an ionic (ioxaglate) and a nonionic (iohexol) low osmolality contrast media on thrombus generation using percutaneous intracoronary angioscopy in patients with unstable angina undergoing percutaneous transluminal coronary angioplasty (PTCA). Thirty patients with unstable angina pectoris randomized to either ioxaglate or iohexol (15 patients in each group), underwent percutaneous intracoronary angioscopy before and after PTCA and 15 minutes after PTCA. Angioscopically visible thrombus was defined using the Ermenonville classification and the lesion divided into 3 zones-proximal, mid, and distal. Angiographic filling defects were seen in 3 patients before PTCA, and in 10 after PTCA. Angioscopically visible thrombus was seen in 10 patients before PTCA in the ioxaglate group and 8 in the iohexol group. After PTCA 5 patients (33.3%) in the ioxaglate and 11 (73.6%) in the iohexol group developed new thrombus, p = 0.028. Total thrombi before PTCA were 16 versus 13, after PTCA 25 versus 27, and at 15 minutes after PTCA 23 versus 25, ioxaglate versus iohexol respectively, p = NS. There was no correlation between type or extent of intimal dissection and angioscopically visible new thrombus formation. Angiography underestimated the incidence of intracoronary thrombus before and after PTCA. Nonionic low osmolality contrast medium was associated with significantly more patients developing angioscopically visible new thrombus. This has clinical implications in the choice of contrast medium used in PTCA, particularly in the setting of unstable angina.