Tissue distribution and magnetic resonance spin lattice relaxation effects of gadolinium-DTPA

Gadolinium-DTPA complex (Gd-DTPA) is a potential clinical magnetic resonance (MR) contrast agent that enhances images primarily by decreasing spin-lattice relaxation time (T1) in tissues in which it localizes. This study was designed to determine the immediate tissue distribution of intravenously administered Gd-DTPA in selected organs of interest as a function of administered dose and tissue Gd-DTPA concentration. An intravenous bolus of Gd-DTPA with a tracer quantity of Gd-153 was administered to three groups of rabbits at the following doses: 0.01 mM/kg (n = 6); 0.05 mM/kg (n = 6); 0.10 mM/kg (n = 6). A control group received sham injections. Five minutes after Gd-DTPA was administered, all animals were killed; samples of serum, lung, heart, kidney, liver, and spleen were analyzed in a 0.25 T MR spectrometer to measure T1, and then in a gamma well counter to determine tissue concentration of Gd-DTPA. Tissue distribution (per cent dose/tissue weight in g) at five minutes after injection was proportionally constant over the range of doses given. Tissue concentration varied linearly with injected dose (r greater than 0.98 for all tissues). Relaxation rate (1/T1) varied linearly with injected dose and with tissue Gd-DTPA concentration (r greater than 0.97 for all tissues). The order of tissue relaxation rate response to a given dose was: kidney greater than serum greater than lung greater than heart greater than liver greater than spleen. We conclude that because of its extracellular distribution and linear relaxation rate versus concentration relationship, Gd-DTPA enhancement in MR images may be a good marker of relative organ perfusion.     

Magnetic resonance imaging and computed tomography features of nasopharyngeal carcinoma with maxillary sinus involvement

Anterior spread of nasopharyngeal carcinoma (NPC) may infiltrate the maxillary sinus. In a prospective study of 114 patients comparing magnetic resonance imaging (MRI) and computed tomography (CT) in the staging of NPC, 10 (9%) patients were noted to have tumour infiltration of the maxillary sinuses. All of the patients except one had associated infiltration of the sphenoidal sinuses indicating advanced local spread. Computed tomography was excellent in outlining the extent of bony erosion and associated soft tissue mass within the antra. T1-weighted images could not demonstrate bony erosions directly although soft tissue extension into the sinuses could be clearly visualized. Both CT and MRI showed good demarcation between tumour and mucosal thickening within the maxillary sinus. Although MRI demonstrated soft tissue involvement more elegantly than CT, it did not appear to offer significantly more information that may affect clinical management.     

一些紫草素衍生物的园二色谱研究

从四川密花滇紫草(Onosma confertum W.W.Smith)和新疆软紫草[Arnebia euchroma (Royle) Johust]的根中分到九个紫草素衍生物,其中七个为手性化合物。测定了它们的CD谱和UV谱,结果得到三对几乎完全对称的CD谱图和完全相同的UV谱图、确定了四川密花滇紫草成分均为R构型;新疆软紫草成分均为S构型。     

Intrathoracic extra-mediastinal cystic hygroma in infancy

An infant with intrathoracic extra-mediastinal cystic hygroma is described. Fluid collection within the fetal chest was noted on routine antenatal ultrasound scan and this was subsequently drained. Postnatally, echocardiogram and thoracic CT scan demonstrated a cystic space between the pericardium and right mediastinal pleura. Thoracotomy performed at six weeks of age showed a multiloculated cystic mass adherent to the right pericardium and to the medial aspect of the diaphragm. Histology revealed the tumour to be a cystic hygroma (lymphangioma). Intrathoracic cystic hygroma occurring outside the mediastinum is extremely rare and has never been diagnosed previously in infancy.     

HLA-A,B,C and DR antigens in a sample of the Tunisian population

The HLA-A, B and DR phenotypes of 109 unrelated Tunisian individuals have been determined. The HLA-A and B antigen frequencies were compared with data reported for European Caucasoids and various Arab populations. Most similarities in antigen frequencies were seen between Tunisians and Kabyles from North Africa. A high frequency of HLA-A23 and HLA-Bw50 was observed in Tunisians and all Arab populations. A very close similarity in HLA-DR antigen frequencies exists between Tunisians and European Caucasoids. Linkage disequilibria between alleles of HLA loci were examined; many instances of previously reported antigen associations were seen in Tunisians, together with a number of associations which have not been described elsewhere. Aw34B8 and A2DRw14 are suggested as being common haplotypes in Tunisians.