Chemometrics for the classification and calibration of seawater using the H+ affinity spectrum.

In 1819 Alexander Marcet proposed that seawater contains small amounts of all soluble substances and that the relative abundances of some of them were constant. This hypothesis is nowadays known as Marcet's Principle or the principle of constancy of the composition of seawater. Based on this principle, the present research tried to prove that it is possible to detect polluted seawater samples using the seawater H(+) affinity spectrum by the application of the possibilities provided by chemometric tools. Seawater samples were classified using the principal component analysis (PCA) of the HBound spectra of the samples. It was concluded that the sampling points location does not have any influence in the cluster formation, while the season in which they were collected is significant. On the other hand, the seawater composition was calibrated using estuary water samples of different salinities. Once the major constituents were measured, the data analysis concluded that it is possible to make a calibration of the HBound spectrum vs. any of these constituents by means of partial least square (PLS) regression. Thus, the experimental evidence collected in this work confirms that it is possible to detect polluted sea or estuary water samples using these chemometric tools and the H(+) affinity spectrum because with polluted samples these multivariate methods lead to incoherent results. So, suspect polluted zones may be monitored in a simple way with a low cost method and spending much less time.

Benign adenomyoepithelioma of the breast: imaging findings mimicking malignancy and histopathological features.

Adenomyoepithelioma of the breast is a rare neoplasm. We present a case of a benign adenomyoepithelioma of the breast in an asymptomatic 60-year-old woman. This report illustrates the mammogram, ultrasound, and magnetic resonance appearances of this unusual lesion, with histopathological correlation.

Bile duct leaks after laparoscopic cholecystectomy: value of contrast-enhanced MRCP.

BACKGROUND: We assessed the role of mangafodipir-enhanced magnetic resonance (MR) cholangiography in the detection and location of bile duct leaks after laparoscopic cholecystectomy. METHODS: In a prospective study, 34 patients with clinical suspicion of bile duct leak after laparoscopic cholecystectomy underwent MR imaging. Our protocol included conventional heavily T2-weighted MR cholangiography and three-dimensional T1-weighted MR cholangiography after an intravenous bolus injection of mangafodipir trisodium. All studies were performed on a 1.5-T or 1-T scanner. Contrast-enhanced MR cholangiograms were evaluated for the presence and location of bile duct leaks. Correlation was obtained in all cases with surgery (n=15), endoscopic retrograde cholangiography (n=5), percutaneous drainage (n=5), and clinical follow-up (n=9). RESULTS: In 20 of 34 patients, bile duct leakage was proved by surgery, endoscopic retrograde cholangiography, or drainage. Contrast enhancement displayed the leakage in 19 of 20 patients and ruled out leaks in the other 14 patients (95% sensitivity, 100% specificity). The leak site was depicted in 14 patients and contrast-enhanced MR cholangiography successfully located the origin of the leak in 11 patients. CONCLUSIONS: Contrast-enhanced MR cholangiography with intravenous mangafodipir trisodium can accurately diagnose the presence and location of bile duct leaks in patients who have undergone laparoscopic cholecystectomy.

Masses and pseudomasses of the hand and wrist: MR findings in 134 cases.

OBJECTIVE: To assess the utility of magnetic resonance imaging (MRI) in the investigation of palpable masses in the hand or wrist. DESIGN AND PATIENTS. We retrospectively reviewed the MRI examinations and case records of 134 patients referred because of a palpable mass in the hand or wrist. MRI was performed on a 1.0 T magnet using an extremity coil. Intravenous gadolinium-DTPA was injected when considered appropriate. RESULTS AND CONCLUSIONS: MRI demonstrated the cause of the palpable mass in 126 cases (94.02%). Soft tissue neoplasms were found in 34 cases (25.37%). The majority were benign and included giant cell tumours of tendon sheath, lipomas and hemangiomas and had a characteristic appearance. There were three malignant tumours (myxoid liposarcoma, malignant fibroushistiocytoma and rhabdomyosarcoma). Ganglia were found in 36 cases (26.86%) and non-tumour tendon pathology in 31 cases (23.13%). Less common causes included articular diseases (5.97%) and anatomical variants (4.47%). No focal lesion was present in 8 cases (5.97%). In conclusion, MRI is an accurate diagnostic technique in patients who present with a palpable mass of the hand and wrist.

Magnetic resonance study of the pancreatic duct.

AIM: to prospectively determine the diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) in the evaluation of the normal and diseased pancreatic duct. METHODS: patients seen during a 6-month period with a diagnosis of biliary tract or pancreatic disease underwent endoscopic retrograde cholangiopancreatography (ERCP) after a previous MRCP. The pancreatic duct was evaluated with both techniques in 37 patients. RESULTS: the pancreatic duct appeared normal in ERCP in 27 patients, and also appeared normal in MRCP in 25 of these patients (specificity 93%). ERCP showed moderate-severe pancreatic duct dilation in 8 patients, in whom the same diagnosis was reached with MRCP (sensitivity 100%). The causes of dilation were chronic pancreatitis (2 patients), pancreatic cancer (3 patients) and ampullary tumor (2 patients); in 1 patient the findings with both techniques were suggestive of neoplasm of the head of the pancreas or focal chronic pancreatitis. Pancreas divisum was diagnosed in 2 patients by both methods, and the predominant dorsal duct as well as the ventral duct were visualized by MRCP. CONCLUSIONS: MRCP is an accurate technique for evaluating the normal or diseased pancreatic duct, and for determining the underlying disease.

Atypical MRI presentation of a small splenic hamartoma.

Hamartomas of the spleen usually appear isointense on T1-weighted MR images and hyperintense on T2-weighted images. We describe a histologically proven case which presented as a small (2.5 cm) focal mass isointense to splenic parenchyma on T1-weighted images and hypointense on both turbo-spin-echo T2 and short T1 inversion recovery images. Dynamic MRI revealed a delayed enhancement during the arterial phase becoming isointense and prolonged on subsequent images. This prolonged enhancement has previously been described as a characteristic pattern in these tumours. The lack of oedema and necrosis and the presence of fibrous tissue in the hamartoma at histopathology likely account for the low signal intensity on all sequences.

Magnetic resonance cholangiopancreatography in the evaluation of pancreatic duct pathology.

MR cholangiopancreatography (MRCP) may replace direct pancreatography in the evaluation of the pancreatic duct. The aim of this pictorial review is to demonstrate the usefulness of MRCP in the evaluation of pancreatic duct pathology. The examination technique included coronal, sagittal and axial breath-hold HASTE 2D imaging using a body phase array coil. We present the diagnostic features on MRCP of a variety of benign and malignant disorders of the pancreatic duct, and conclude that MRCP is a suitable method for imaging the pancreatic duct system.

Postmediastinoscopy changes in chest CT.

OBJECTIVE: To know the CT changes that may be seen in the mediastinum after uncomplicated mediastinoscopy. MATERIALS AND METHODS: Noncontrast CT was performed on 10 patients on the 1st, 3rd, and 5th days after the procedure. RESULTS: We encountered linear and diffuse increased attenuation within the mediastinum as well as air bubbles. By the 5th day postmediastinoscopic changes resolved. We never found air-fluid levels, fluid collections, or other abnormalities. CONCLUSION: Expected postmediastinoscopic changes are not to be confused with potential postprocedure complications such as hemorrhage or infection.