pH and concentration dependence of the optical properties of thiol-capped CdTe nanocrystals in water and D2O.

The optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical composition and thickness of inorganic passivation shells and the chemical nature and number of surface ligands as well as the strength of their bonds to surface atoms. The latter is particularly important for CdTe NCs, which - together with alloyed CdxHg1-xTe - are the only SC NCs that can be prepared in water in high quality without the need for an additional inorganic passivation shell. Aiming at a better understanding of the role of stabilizing ligands for the control of the application-relevant fluorescence features of SC NCs, we assessed the influence of two of the most commonly used monodentate thiol ligands, thioglycolic acid (TGA) and mercaptopropionic acid (MPA), on the colloidal stability, photoluminescence (PL) quantum yield (QY), and PL decay behavior of a set of CdTe NC colloids. As an indirect measure for the strength of the coordinative bond of the ligands to SC NC surface atoms, the influence of the pH (pD) and the concentration on the PL properties of these colloids was examined in water and D2O and compared to the results from previous dilution studies with a set of thiol-capped Cd1-xHgxTe SC NCs in D2O. As a prerequisite for these studies, the number of surface ligands was determined photometrically at different steps of purification after SC NC synthesis with Ellman's test. Our results demonstrate ligand control of the pH-dependent PL of these SC NCs, with MPA-stabilized CdTe NCs being less prone to luminescence quenching than TGA-capped ones. For both types of CdTe colloids, ligand desorption is more pronounced in H2O compared to D2O, underlining also the role of hydrogen bonding and solvent molecules.

[Local vertebral body destruction after migration of a nucleus replacement]. / Lokale Wirbelkörperdestruktion nach Migration eines Nukleusersatzimplantates.

We present the case report of a 32-year-old female suffering from severe low back pain because of local vertebral body destruction at L3/4 after migration of PDN-SOLO nucleus replacement. Removal of the dislocated implant via a posterior transforaminal approach was not possible. After posterior stabilisation the implant could be salvaged from the anterior direction, but stabilisation with a vertebral body replacement was necessary.

[Transbrachial arterial catheter angiography. Technique, indications, complications]. / Die transbrachiale arterielle Katheter-Angiographie. Technik, Indikationen, Komplikationen.

In a large group of patients, most of whom were attending a department of vascular surgery, who underwent arterial digital subtraction angiography (DSA), a transfemoral approach was not possible in 9%. Therefore in 142 cases transbrachial arterial angiography was electively performed with 4-F or 5-F catheters. This method proved to be a safe and reliable alternative, though the examination technique was more demanding and the complication rate somewhat higher. It offers clear advantages over a transaxillary or translumbar approach. Special attention is paid to the role of transbrachial arterial DSA in evaluating the descending aorta and the peripheral outflow in the legs and to its usefulness in certain angioplasty manoeuvres.

[CT and MRT of vertebral hemangiomas]. / CT und MRT von Wirbelhämangiomen.

A retrospective comparative study of CT and MRI was carried out involving 38 vertebral haemangiomas; this revealed a typical signal pattern on MRI from benign lesions. It consists of a hyper-intense signal from the bone marrow affecting the T1/T2 sequences; this may be focal or involve the entire vertebral body. These characteristic signals were compared with CT images of the spine. The areas of bone that produce the high intensity signals on MRI appear on CT as spongy patterns with hypertrophic trabeculae surrounding mostly areas with negative absorption values. An analysis of the changes in the spongiosa has revealed three clearly defined types. The signals derived from haemangiomas extending beyond the bone have an intensity of normal spongiosa; this corresponds with an absence of fat, as demonstrated by CT. Extra-osseous components have low intensity T1 signals that increase in T2 sequences.

[The MRT demonstration of bone marrow changes in intervertebral disk degeneration]. / Die Darstellung von Knochenmarkveränderungen bei Bandscheibendegeneration im MRT.

Amongst 214 patients with degenerative disc disease, MRT showed focal fat deposition in the vertebral marrow close to the end plate in 87 (41%). The appearances and distribution of these zones is described. Recognition of these common changes is important in differential diagnosis between inflammatory and neoplastic processes.

[Imaging of neoplastic changes in the spine using MR tomography]. / Die Darstellung neoplastischer Wirbelveränderungen durch die MR-Tomographie.

The value of MR tomography for examining vertebral infiltration by malignant disease and the use of various techniques was examined retrospectively in a material of 68 examinations in 62 patients suffering from metastases, plasmacytomas, primary vertebral tumours and vertebral infiltration from extra-osseous tumours. It was shown that the method is superior to all other imaging methods for demonstrating changes in the bone marrow. The extent of the disease and involvement of neighbouring structures is shown more completely in cases where the disease extends beyond the vertebrae. Improved soft tissue contrast and the availability of various planes are definite advantages, as compared with CT. Tissue diagnosis, however, is not improved by MRT.

[Diagnosis of spondylitis by MR tomography]. / Diagnostik der Spondylitis durch die MR-Tomographie.

The results of MR tomography in 13 patients with specific and nonspecific spondylitis are reported. There were characteristic changes in signal intensity and in the configuration of the vertebral bodies and the intervertebral discs. The extent of intraspinal stenosis can be demonstrated accurately by MR. Paravertebral abscesses can be shown accurately and their position can be clarified by means of multiplanar sections. The early diagnosis of spondylitis by MR tomography is discussed.

Computed tomography and magnetic resonance of pseudomyxoma peritonei.

Computed tomographic and magnetic resonance (MR) findings in a case of pseudomyxoma peritonei arising from a mucoid cystadenoma of the ovary are presented. The possible diagnostic aid of MR is discussed.

[Computer tomography in diagnosis of ovarian cancer]. / Computertomogramm in der Diagnostik des Ovarialkarzinoms.

In 90% of all cases an ovarian tumor about 2 to 3 cm in size can be visualized computertomographically using a contrast medium. Determination of the dignity can be achieved in about 81% of all cases. Malignant tumors which are impressive as smooth-walled cysts are only recognized as such in 50% of all cases. Correct staging also occurs in 50% of all cases. An accuracy of about 90% can be expected in aftercare.

Renal abscess: report of a case with sonographic, urographic and CT evaluation.

The appearance of a renal abscess on realtime-ultrasound, excretion urography and computed tomography is presented of an operatively and histologically proven case. An unusually hyperdense rim of the lesion is observed on native CT-scan. Knowledge of clinical symptoms is most important for correct interpretation of diagnostic imaging techniques.

[Radiologic diagnosis of metastases in the lesser pelvis]. / Radiologische Diagnostik von Metastasen im kleinen Becken.

Reviewing the literature and summarizing our own experience, the role of various imaging modalities concerning diagnosis of metastases to lymph nodes and organs in the pelvic cavity is discussed. Especially ultrasound, CT and lymphography are compared, the importance of fine-needle-aspiration is emphasized. Possible advantages of MRI are mentioned.

[Possibilities of conventional intravenous subtraction angiography]. / Möglichkeiten der konventionellen intravenösen Subtraktionsangiographie (ISA).

Basing on the experiences collected with 127 patients, the pros and cons as well as the indications for intravenous angiography with conventional photographic subtraction technique (ISA) are discussed in comparison with rival procedures. ISA can be performed in every angiography unit without any additional investment, and its possibilities of use are identical with those of the DSA. As a matter of fact, it is a simple and safe method for visualising the renal arteries in the course of intravenous urography in the diagnostic evaluation of hypertension. For the first time, it has become possible to perform transvenous determination of the complete status of the arteries of the pelvis and legs, using a new technical system (simultaneous use of two film changers in the frontal plane--ISA aortoarteriography.

[Diagnostic procedure in a solitary angiomyolipoma of the kidney]. / Diagnostisches Vorgehen beim solitären Angiomyolipom der Niere.

The use of excretion urography, sonography, ultrasound-controlled fine-needle puncture, computed tomography and angiography is described in four histologically confirmed cases of solitary renal angiomyolipomas. For the second time, involvement of the inferior vena cava by a benign hamartoma is described. An important advance is the recognition of a characteristic collection of findings consisting of strong echogenicity on ultrasound and fat equivalent hypodensity on CT, together with the cytological findings, which are described for the first time. It was possible to make the diagnosis with a high degree of certainty in two patients, with important therapeutic implications.

[Very rapid bolus injection as routine method in excretion urography (author's transl)]. / Bolus - Kurzinjektion als Routinemethode bei der Ausscheidungsurographie.

The authors report on a comparative examination of the tolerance and diagnostic value of excretion urography using a standard dose of 50 ml of a 77% solution of the meglumine-sodium salt of ioxythalamic acid (Telebrix 390) at conventional injection speed (60-90 sec.) compared with a very rapid bolus injection (less than 10 sec.) Although the risk of severe side effects is probably the same in both cases, the rate of mild or so-called non-specific side effects is significantly lower with the more rapid type of injection. At the same time, it is possible to improve the diagnostic value with a slightly greater effort (vascular early nephrogram).