Imaging update on cartilage.

In this update article, we present a review of the literature regarding the physiology of the articular cartilage, role of MR imaging in cartilage assessment, MRI sequences and protocols for cartilage imaging, brief overview of classifications and nomenclature for chondral and osteochondral lesions, MR imaging following cartilage repair and degenerative osteoarthritis.

Contrast-enhanced intraoperative ultrasound improves detection of liver metastases during surgery for primary colorectal cancer.

BACKGROUND: Computed tomography (CT) is the most common staging investigation in colorectal cancer (CRC). Up to 25% of patients are found to have previously undetected hepatic lesions when intraoperative ultrasound (IOUS) of the liver is used during CRC resection. We aimed to assess the ability of IOUS to detect additional liver lesions/metastases at primary colorectal resection, and to evaluate whether contrast-enhanced IOUS (CE-IOUS) improves the detection and characterization of hepatic lesions. METHODS: We performed a single-centre, prospective pilot study. At CRC resection, patients underwent IOUS of the liver. Contrast-enhanced IOUS of the liver was undertaken using i.v. sulphur hexafluoride micro-bubbles (SonoVue, 4.8 ml). Findings of CT, non-enhanced IOUS and CE-IOUS were compared. Changes in staging or management were noted. Additional lesions were corroborated with iron oxide magnetic resonance imaging (MRI). RESULTS: Among 21 patients, IOUS demonstrated additional lesions in seven (33%). Contrast altered the diagnosis of non-enhanced IOUS in four (20%) and changed the management strategy in three (14%) patients. Thus, IOUS in combination with the contrast agent altered the intraoperative or postoperative management plan in four patients. CONCLUSIONS: In the first study of its kind, early results suggest that the ability of IOUS to detect additional metastases is improved by CE-IOUS, and that this may impact on surgical staging and management.

MR cholangiopancreatography at 3.0 T.

The rapid evolution of magnetic resonance (MR) imaging technology has produced much-needed improvements in temporal and spatial resolution that have led to greater recognition of diseases of the hepatobiliary and pancreatic ducts at MR cholangiopancreatography. This modality often substitutes for diagnostic evaluations with endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography. Recent innovations in whole-body MR imaging, including fast imaging sequences, phased-array coils, parallel imaging techniques, and 3.0-T magnets, allow the acquisition of higher-quality diagnostic images in less time. An understanding of these technical advances and their potential clinical applications, limitations, and pitfalls for cholangiopancreatographic evaluation is as essential as a familiarity with the spectrum of possible findings; both are needed to accurately identify and characterize the disease process and to provide effective guidance for treatment.

The clinical impact of magnetic resonance imaging in diagnosing focal hepatic lesions and suspected cancer.

AIMS: To compare the clinical utility of contrast enhanced magnetic resonance imaging (MRI) to ultrasound (USS) and computed tomography (CT) in focal hepatic lesions (FHLs) METHODS: This retrospective study analysed 125 consecutive iron oxide enhanced (SPIO) MRI. RESULTS: MRI made a difference in 74% of patients who had USS and in 42% of patients who had a CT scan. In suspected cancer, MRI changed diagnosis in 58% and 37% (13/35), respectively. CONCLUSIONS: MRI is superior to other noninvasive imaging modalities for lesion identification and characterisation.

Rheological characterization of neutral and anionic polysaccharides with reduced mucociliary transport rates.

The purpose of this research was to compare the viscoelastic properties of several neutral and anionic polysaccharide polymers with their mucociliary transport rates (MTR) across explants of ciliated bovine tracheal tissue to identify rheologic parameters capable of predicting the extent of reduction in mucociliary transport. The viscoelastic properties of the polymer gels and gels mixed with mucus were quantified using controlled stress rheometry. In general, the anionic polysaccharides were more efficient at decreasing the mucociliary transport rate than were the neutral polymers, and a concentration threshold, where no further decreases in mucociliary transport occurred with increasing polymer concentration, was observed for several of the neutral polysaccharides. No single rheologic parameter (eta, G', G'', tan delta, G*) was a good predictor of the extent of mucociliary transport reduction, but a combination of the apparent viscosity (eta), tangent to the phase angle (tan delta), and complex modulus (G*) was found to be useful in the identification of formulations capable of decreasing MTR. The relative values of each of the rheologic parameters were unique for each polymer, yet once the relationships between the rheologic parameters and mucociliary transport rate reduction were determined, formulations capable of resisting mucociliary clearance could be rapidly optimized.

Formulating gels for decreased mucociliary transport using rheologic properties: polyacrylic acids.

The purpose of these studies was to identify the rheologic properties of polyacrylic acid gels necessary for optimal reductions in mucociliary clearance. The mucociliary transport of 2 bioadhesive polyacrylic acid polymers, polycarbophil and carbopol, was assessed in vitro by measuring their clearance rates across explants of ciliated bovine tracheal tissue. The viscoelastic properties of polymer gels were measured in the presence of mucus using controlled stress rheometry. Combinations of apparent viscosity (eta) and complex modulus (G*) were found to be the most useful parameters in the identification of polyacrylic acid formulations capable of decreasing mucociliary transport rate (MTR). A narrow range of eta and G* values suitable for reducing mucociliary clearance, while remaining sufficiently fluid for intranasal administration, were identified. The correlations between the rheologic parameters of the polycarbophil gels and their mucociliary transport rates were used to identify other polyacrylic acid gels that also had suitable mucociliary clearance properties, demonstrating that these parameters can be used to direct the optimization of formulations using simple in vitro rheologic testing.

Viscoelastic gel formulations enhance airway epithelial gene transfer with viral vectors.

Advances in gene transfer to the conducting airways for the treatment of pulmonary diseases such as cystic fibrosis have identified several vector classes that transduce airway epithelia in vitro and in animal models. One barrier to epithelial gene transfer is the rapid removal of materials from the airway surface via mucociliary clearance. This host defense mechanism limits gene transfer efficiency to airway epithelial cells. Here we show that formulation of gene transfer vectors with viscoelastic gels provides longer epithelial residence time and increases vector-mediated gene transfer efficiency. Gene transfer with adenoviral, adeno-associated, and lentiviral vectors all significantly improved after formulation with viscoelastic gels designed to slow mucociliary clearance. Importantly, viscoelastic gel formulations enhanced vector transduction to the conducting airways, the desired treatment target for diseases such as cystic fibrosis.