Rotation due to hydrodynamic interactions between two spheres in contact.

We analyze the rotational and translational motion of two close spheres in a fluid at low Reynolds number to investigate if their surfaces come into mechanical contact. The rotational motion of a sphere settling close to another fixed ball is calculated from a model in which contact interactions between the spheres are added to the gravitational and hydrodynamic forces. The model predicts a transition from pure rolling to rolling with slip, determined by the Coulomb's law, when the ratio of the mechanical friction to the load increases up to the static friction coefficient. The dependence of the angular and translational velocities on the kinetic friction coefficient and on the separation between the particle surfaces is analyzed. The angular and translational velocities of a millimeter size bead in a viscous oil, close to a fixed bead of a similar size, are measured from video images. Interferometric data on translational motion are also collected according to the method introduced in our earlier studies. A systematic fitting procedure of the model to the experiment is developed and applied to the rotational and translational measurements. The model parameters are determined.

[99mTc-nanocolloid: clinical results of its use as a new inflammation marker]. / 99mTc-Nanokolloid: Klinische Ergebnisse im Einsatz eines neuen Entzündungsmarkers.

Fifty scintigrams were performed on 45 patients using 99mTc-nanocolloid in order to test its affinity for inflammatory lesions; in these patients there was clinical and/or radiological suspicion of an inflammatory process. There was good correlation between the degree of uptake and the activity of the inflammatory process. Specificity is limited because of uptake in certain tumours (eg. sarcomas of the extremities), but difficulties in differential diagnosis are not expected to be serious. Judging by our experience, 99mTc-nanocolloid is a promising substance for the scintigraphic demonstration of inflammatory foci. The advantages of this industrially prepared tracer over In-leucocytes and Ga-citrate are discussed.

[CT cavography: diagnosis of iliocaval thrombosis by administration of contrast medium into the foot]. / CT-Kavographie: Diagnostik iliokavaler Thrombosen mit pedaler Kontrastmittelapplikation.

CT permits demonstration of thrombus in the iliac veins and inferior vena cava by injecting contrast material into vein in the dorsum of the foot. This technique, called CT cavography in this paper, has advantages over conventional venography or DSA and also over sonography. It is indicated following phlebographic demonstration of recent pelvic thrombosis and for demonstrating tumour thrombi in patients with carcinomas of the kidney.

[Reversible fatty infiltration of the liver parenchyma in acute pancreatitis]. / Die reversible Leberparenchymverfettung bei akuter Pankreatitis.

Case studies show that acute pancreatitis occurring independently or combined with a preceding abuse of alcohol may be the cause of fatty infiltration of the liver. These fat areas can evolve in a very short time and provoke in the case of focal incidence diagnostic problems of differentiation against abscesses or metastases. Due to this fact and because of the rapid reversibility of the fatty infiltration under therapy, the safest method to clarify the situation consists of short-term CT controls.

[Spinal scintigraphy following Harrington's spondylodesis]. / Wirbelsäulen-Szintigraphie nach Harrington-Spondylodese.

About one year after Harrington-Spondylodesis in 29 patients scintigraphy was performed in order to find non-unions. Scintigraphy is more successful in this question and can be recommended in routine-diagnostics.

[Value of radiotherapy in metastases of hypernephroid carcinoma]. / Wertigkeit der Strahlentherapie bei Metastasen des hypernephroiden Karzinoms.

52 own cases are retrospectively evaluated in order to investigate the importance of radiotherapy for the treatment of the metastasizing hypernephroma. The treatment is above all indicated in case of painful osseous metastases, but the success is retarded and often appears only after a focal dose of more than 30 Gy. Furthermore, radiotherapy of brain metastases and lymph node metastases within the mediastinum is often successful, whereas the irradiation of pulmonary metastases has to be judged less favorably. In most of all cases, surgical interventions are not an alternative, but a complementary treatment to radiotherapy. In default of promising systemic therapy methods, radiotherapy of metastases of the hypernephroma are a possibility to achieve a real palliative effect.

Single-photon emission computed tomography (SPECT) for assessment of hepatic lesions.

Single-photon emission computed tomography (SPECT) and conventional scintigraphy were compared in 130 patients examined to assess hepatic involvement in malignant disease. Transmission computed tomography (TCT) served as the reference method against which SPECT and conventional scintigraphy were compared. The sensitivity of SPECT was calculated for lesions grouped according to diameter as well as location. The Bayesian theorem was used to assess the reliability of both SPECT and conventional scintigraphy. SPECT identified only 52% of lesions with a diameter of 1.5-2.0 cm. It was also shown that the sensitivity of SPECT was lowest for small lesions in the middle third of the liver. A comparison of the final diagnosis demonstrated that SPECT had greater sensitivity, specificity, and accuracy than conventional scans, and is superior at low disease prevalence. At high disease prevalence, SPECT has a lower rate of false negatives. SPECT appears to be the superior imaging modality for evaluation of the liver in malignant disease.

[The scintigraphic diagnosis of pseudo-arthroses following Harrington's spondylodesis (author's transl)]. / Szintigraphische Diagnostik von Pseudarthrosen nach Harrington-Spondylodese.

The development of pseudo-arthroses is the most common complication following operative treatment of severe scoliosis. Early recognition of this event is important to prevent recurrence of the curvature. The diagnosis is not possible by radiological examination of the rigid spine. Routine reexploration implies a second operation, which is unnecessary in the majority of patients with stable fusion. In an attempt to develop a non-invasive method for the diagnosis of pseudo-arthroses, bone scintigrams were carried out in 29 patients with idiopathic scoliosis twelve months after a Harrington's spondylodesis. In 24 patients (82.8%) a definite conclusion could be drawn, either of stable fusion (65.5%) or pseudo-arthrosis formation (17.3%). No pseudo-arthroses were missed by scintigraphy. These results indicate that bone scintigraphy plays an important role in the post-operative care after Harrington's spondylodesis.

[The diagnostic significance of 99mTc-marked phosphate uptake in the soft tissues of the breast (author's transl)]. / Die diagnostische Bedeutung der Speicherung 99mTc-markierter Phosphate im Weichteilgewebe der Mamma.

A patient with a right-sided carcinoma of the breast had a bone scintigram with 99mTc-methylendiphosphonate (99mTc-MDP), which showed intensive uptake in the abnormal breast; a year after mastectomy, similar high uptake of the drug was found in the remaining breast. The radiological findings indicated a fibrocystic mastopathy without evidence of malignancy in the left breast. A review of the literature suggested that uptake of osteotropic polyphosphate compounds in the breast was of considerable significance, indicating incipient or developing malignancy. A review of our own cases cast considerable doubt on this interpretation. It is probable that MDP uptake in the breast depends in part on the hormonal pattern and may occasionally be observed during oestrogen therapy in the male (eg. carcinoma of the prostate).

[A comparison of static liver scintigrams in supine and erect patients (author's transl)]. / Vergleich statischer Leberszintigramme bei liegendem und stehendem Patienten.

The study compares the results of liver scintigrams performed on patients whilst standing and lying down. One hundred and ten patients were examined and in 12 cases, examination in the erect position lead to important diagnostic information. By changing position, it is possible to exclude apparently abnormal defects of uptake; on other occasions the changed configuration of the liver permits the recognition of genuine lesions. Additional examinations on the erect patient help to reduce the incidence of false positive and false negative findings during liver scintigraphy.