Observer accuracy in the detection of pulmonary nodules on CT: effect of cine frame rate.

AIM: To assess the effect of cine frame rate on the accuracy of the detection of pulmonary nodules at computed tomography (CT). MATERIALS AND METHODS: CT images of 15 consecutive patients with (n = 13) or without (n = 2) pulmonary metastases were identified. Initial assessment by two thoracic radiologists provided the "actual" or reference reading. Subsequently, 10 radiologists [board certified radiologists (n = 4) or radiology residents (n = 6)] used different fixed cine frame rates for nodule detection. Within-subjects analysis of variance (ANOVA) was used to evaluate the data. RESULTS: Eighty-nine nodules were identified by the thoracic radiologists (median 8, range 0-29 per patient; median diameter 9 mm, range 4-40 mm). There was a non-statistically significant trend to reduced accuracy at higher frame rates (p=0.113) with no statistically significant difference between experienced observers and residents (p = 0.79). CONCLUSION: The accuracy of pulmonary nodule detection at higher cine frame rates is reduced, unrelated to observer experience.

HIV encephalitis despite suppressed viraemia: a case of compartmentalized viral escape.

There is increasing concern that HIV treatment failure may result from inadequate central nervous system (CNS) penetration of antiretroviral drugs, allowing compartmentalized viral replication and development of resistance. We discuss a patient who maintained a suppressed plasma viral load for four years on antiretroviral therapy (ART) before developing HIV encephalitis with a cerebrospinal fluid (CSF) HIV viral load of 861 copies/mL and newly detectable plasma viral load of 68 copies/mL. Identification of major resistance mutations to his combination therapy supported concerns that resistant HIV had developed within the CNS. His ART was changed to optimize CNS penetration, leading to maintained clinical improvement. Imaging presented demonstrates corresponding radiological improvement. The report illustrates the need to exclude CNS viral rebound or incomplete suppression in HIV patients with neurological symptoms, and suggests that the extent of this emerging problem is only beginning to be recognized as the implications of long-term peripheral HIV suppression unfold.

Comparative study of experienced vs non-experienced radiologists in assessing parametric CT images of the response of the prostate gland to radiotherapy.

Functional CT can demonstrate acute quantitative increases in perfusion, permeability and fractional vascular volume in the prostate gland of patients with prostate cancer following radiotherapy (RT). We hypothesize that these quantitative changes can also be demonstrated visually by presenting them as colour parametric maps using custom software. 21 patients with prostate cancer were studied before, and 1-2 weeks after, RT. Repeated CT scans through a single section of the prostate was performed following contrast injection. Capillary permeability, fractional vascular volume and tissue perfusion were calculated and converted to colour maps using a customized Matlab imaging programme. Five "expert" and five "novice" radiologists scored pairs of randomized prostate images as an "increase", "decrease" or "no change" in intensity following RT. Kappa (kappa) statistics was used to assess the concordance of opinions. Significant quantitative increases in all indices occurred after RT, and almost all of the parametric images were scored as an increase in intensity following RT (perfusion = 95%, permeability = 88%, volume = 84%). There was substantial agreement between the experts and novices (kappa: perfusion = 0.93, permeability = 0.80, volume = 0.90), as well as within the expert (kappa: perfusion = 1, permeability = 0.86, volume = 1) and novice (kappa: perfusion = 0.82, permeability = 0.78, volume = 0.78) groups. Functional colour maps of the prostate can reliably portray the hyperaemic response following RT in a group with quantitative increases in perfusion, permeability and fractional vascular volume, and provides a potentially accessible and convenient method for image analysis by radiologists of varying experience.

The use of intraoperative monitoring and treatment of symptomatic microemboli in carotid artery stenting: case report and discussion.

Carotid artery stenting is a recently introduced treatment in symptomatic atherosclerotic carotid artery disease with acceptable complication rates. The major risk is perioperative embolic stroke. Transcranial Doppler ultrasonography (TCD) can be used to identify embolic signals and guide therapy. We present a case of symptomatic embolization in a 72-year-old female following carotid stent deployment complicated by haemodynamic changes. Despite concurrent dual antiplatelet medication significant symptomatic embolization occurred even after restoration of the blood pressure, and modulation of the rate of embolization was achieved using dextran-40 guided by TCD monitoring. The patient recovered from an initially profound hemiparesis and dysphasia to minor sensory changes. Microemboli are common following carotid artery stenting and there appears to be a threshold phenomenon associated with prolonged embolization and progression to cerebral infarction. TCD can be used to detect particulate microemboli and therefore may be useful in guiding antithrombotic therapy in this setting. Dextran-40 has been shown to reduce the embolic load following carotid endarterectomy and was used to good effect in this patient in terms of both embolic load and clinical outcome. This is the first case of embolization following carotid stenting successfully treated with dextran-40, and offers a further option for therapeutic intervention in microembolism detected by TCD and stresses the importance of perioperative monitoring of embolic load for postoperative stroke risk.

Posterior reversible encephalopathy syndrome: a possible late interaction between cytotoxic agents and general anaesthesia.

A 49-year-old woman who had previously received treatment with cytotoxic drugs for metastatic gestational trophoblastic disease (GTD) presented with a witnessed tonic-clonic seizure, headache, confusion and blindness, 6 days after the uneventful administration of a general anaesthetic and 2 months after cessation of chemotherapy. Magnetic resonance imaging showed relatively symmetrical, subcortical, white matter abnormalities, predominantly affecting the occipital, posterior temporal and parietal lobes and the cerebellum. T2-dependent abnormalities and elevated regional apparent diffusion coefficient were present in a pattern typical for posterior reversible encephalopathy syndrome (PRES). The clinical and radiological manifestations were resolved completely with supportive therapy. This case of PRES may be a late complication of gemcitabine or cisplatin therapy precipitated by a general anaesthetic, or associated electrolyte or blood pressure disturbance.