[Systematic errors in clinical studies : A comprehensive survey]. / Systematische Fehler in klinischen Studien : Eine Übersicht.

Systematic errors and related phenomena represent an intrinsic challenge to the quality of clinical research. As a consequence even otherwise methodologically demanding studies may produce results that systematically differ from the true values. Systematic errors relating to investigative medicine are divided into six groups according to their affiliation with the consecutive chronological sections of the study. Bias can occur in preliminary literature research in the field, specifying the study design and selecting the study sample, measuring exposure and outcome, analyzing the data, interpreting the analyses and publishing the results. The most important systematic errors that concern diagnostic and interventional studies are created by access to the data of previous tests, calculated study design, preselection of the participants, comparison with non-contemporaneous controls, antedating the time of diagnosis and overdiagnosis of slowly progressive forms of diseases examined. Checking the measured values often leads to a mosaic of several biases with one being more or less dominant. Even by exercising due care in the preparation and performance of the study, the majority of distortions cannot be eliminated but only diminished. It is essential to consider each detected bias as a potential full or partial argument in support of an observed correlation. The control of systematic errors and related phenomena is both a significant element of the discussion of the study report and a key element for assessment of its scientific value.

[Systematic errors in clinical studies : A comprehensive survey]. / Systematische Fehler in klinischen Studien : Eine Übersicht.

Systematic errors and related phenomena represent an intrinsic challenge to the quality of clinical research. As a consequence even otherwise methodologically demanding studies may produce results that systematically differ from the true values. Systematic errors relating to investigative medicine are divided into six groups according to their affiliation with the consecutive chronological sections of the study. Bias can occur in preliminary literature research in the field, specifying the study design and selecting the study sample, measuring exposure and outcome, analyzing the data, interpreting the analyses and publishing the results. The most important systematic errors that concern diagnostic and interventional studies are created by access to the data of previous tests, calculated study design, preselection of the participants, comparison with non-contemporaneous controls, antedating the time of diagnosis and overdiagnosis of slowly progressive forms of diseases examined. Checking the measured values often leads to a mosaic of several biases with one being more or less dominant. Even by exercising due care in the preparation and performance of the study, the majority of distortions cannot be eliminated but only diminished. It is essential to consider each detected bias as a potential full or partial argument in support of an observed correlation. The control of systematic errors and related phenomena is both a significant element of the discussion of the study report and a key element for assessment of its scientific value.

[As valuable as an organ donation. Enrollment in a clinical study requires patient willingness to make sacrifices]. / So kostbar wie eine Organspende. Die Teilnahme an einer klinischen Studie verlangt von den Patienten Opferbereitschaft.

Patients are by far the most important partners within the complete ensemble involved in clinical studies. Their participation involves a number of additional inconveniencies. Not infrequently, the consent discussion is followed by complementary diagnostic procedures. Besides the objective pressure of expectation there are also subjective fears, which increase in weight the longer the study progresses. During the post-observational period, participants are periodically requested to undertake further control examinations at varying time intervals. By means of their consent, study patients volunteer as supporters in favor of the anonymous successors in the study suffering from the same disease. Obviously, the sacrifices which the enrolled patients make for medical research can be placed on a par with organ donations.

Distribution pattern of Sjögren's syndrome: a sialographical study.

BACKGROUND/OBJECTIVES: The present controlled sialographical study was conducted to learn more from the horizontal and vertical symmetry of the ductal lesions of the major salivary glands in primary (pSS) and secondary (sSS) forms of the disease. MATERIALS AND METHODS: A total of 98 patients (38 pSS patients, 38 sSS patients, 22 control subjects) were included in the study. Contrast radiography of both parotid and submandibular glands was performed within the same session. A 6-point scoring system allowed summary indexes for each of the glands to be calculated. RESULTS: Pansialography was accomplished within 30 min each. The sparsity of the branching pattern of the ducts was the most frequent pathological finding. In pSS, horizontal symmetry was more pronounced in the parotid glands, whereas in sSS it was more pronounced in the submandibular glands. The most discriminating features were the width of the peripheral ducts in the parotid and the number of acinar dilatations in the submandibular glands. The most advanced lesions were found in the left parotid gland. CONCLUSION: The peripheral ducts are more affected by SS than the main excretory duct. There is a tendency for asymmetric involvement of the parotid glands in pSS and of the submandibular glands in sSS. Parotid glands are globally more involved than submandibular glands. Differential diagnosis between pSS and sSS cannot be accomplished by means of pansialography alone. Left parotid sialography is recommended for routine use.

[Combined use of contrast media containing iodine and gadolinium for imaging and intervention : A hitherto widely ignored topic in radiological practice]. / Kombinierter zeitnaher Einsatz jod- und gadoliniumhaltiger Kontrastmittel in der diagnostischen und interventionellen Radiologie : Ein bisher vernachlässigtes Kapitel der radiologischen Praxis.

The synchronous use of chemically different contrast media in the same body compartment is a challenge for the radiologist, whether it is scheduled or unexpected. However, to inject contrast media containing iodine and gadolinium at the same time can be a prerequisite for the examination of several organs or organ systems. Unlike other topics of contrast-enhanced imaging procedures, the difficulties encountered with double contrast injections have been widely ignored in the literature. In the absence of reliable data from experimental and clinical studies the radiologist is dependent on case reports, information provided by the contrast media manufacturers, personal communications, mostly scanty personal experiences and a skilful time management, in order to overcome the situation. Only the combination of X-ray, computed tomography and magnetic resonance arthrography can be performed without another thought. However, the more or less synchronous vascular application of contrast media containing iodine and gadolinium requires vigilance. The more seriously ill the patient is, the more caution is advised even if the decision on the combined administration has to be reached urgently. The following overview gives a description of the properties of contrast media containing iodine and gadolinium as far as interactions following simultaneous administration are concerned. Subsequently, the clinically relevant situations and constellations are outlined and analyzed.

[Phraseology of disk herniation: an inevitable revision renaming the posterior disk prolapse--retrolapse is better]. / Phraseologie des Bandscheibenvorfalls: Eine unvermeidliche Korrektur Der dorsale Diskusprolaps sollte künftig als Retrolaps bezeichnet werden.

Etymology teaches us to use the term prolapse exclusively for describing the part of the intervertebral disk that has slipped forwards, that is, towards the anterior longitudinal ligament. Consequently, the word retrolapse has to be introduced as the corresponding term in order to designate the posterior slipped disk. The common use of matching pairs like propulsion/retropulsion or prognathism/retrognathia is another justification for the recommended revision.

[The Will Rogers phenomenon and its impact on imaging diagnostics]. / Das Will-Rogers-Phänomen und seine Bedeutung für die bildgebende Diagnostik.

The Will Rogers phenomenon is a possible cause of systematic distortions in the results of clinical studies, which can be produced if stage migration occurs during a disease. The term refers to the apparent paradox which is observed when an element is changed from one set to another and the average values of both sets are altered in the same way. The effect is due to the prerequisite that the numerical value of the element being moved is placed between the mean values of both groups. In medicine, this phenomenon is a consequence of the evolution of staging procedures and may be source of misleading statistics for survival in cancer. Both advanced pathological assessment and modern imaging techniques may be involved. The wrong conclusions are induced by comparing the effects of treatment in contemporary patient groups, which profit from extensive diagnostic procedures, to those of historical controls. Treatise informs about the history of the term and illustrates its effects by numerical examples and clinical data. Finally, a model computation based on current PET/CT figures is offered.

[Tortuosity and calcification of the splenic artery. More than an additional finding]. / Schlängelung und Verkalkung der Milzarterie im Röntgenbild. Mehr als ein Nebenbefund.

Tortuosity of the splenic artery and calcification of the vessel wall are typical additional findings on plain abdominal x-ray. The combination of both anomalies is common in elderly persons presenting without symptoms of splenic ischemia. Its pathogenesis is thought to be multifactorial. In infancy and childhood, the splenic artery is stretched in its entire course. A growing difference between the length of the vessel and the distance between its origin and the splenic hilum gives rise to tortuosity. The artery's proximal segment is involved more frequently and more severely than the distal one. The tortuous route of the vessel is accentuated by the direction of its major branches, which is roughly perpendicular to the main trajectory. Neither tortuosity nor calcification should be taken to be risk factors for the comparatively common splenic artery aneurysm. Calcific deposits are not confined to the media but are also detected in the intima of the vascular wall. Critical narrowings of the lumen arising on the calcium deposits are not observed. Calcifying atherosclerosis of the splenic artery is comparable to medial sclerosis of the peripheral arteries frequently noticed in diabetics and dialysis patients. Only the less important calcification of the intima may be attributed to mechanisms of the hydrohemodynamic theory of atherosclerosis. The spleen's blood storage capacity may contribute to the characteristic age-dependent alterations of the shape and course of the splenic artery.

Assessment of acute spinal inflammation in patients with ankylosing spondylitis by magnetic resonance imaging: a comparison between contrast enhanced T1 and short tau inversion recovery (STIR) sequences.

OBJECTIVES: To compare the performance of two different MRI sequences-T(1) weighted, fat saturated, spin echo after application of contrast medium, and short tau inversion recovery (STIR) sequences-to detect spinal inflammation in patients with ankylosing spondylitis (AS). METHODS: Both MRI sequences were performed in 38 patients with active AS and compared using the MRI activity scoring system, ASspiMRI-a. One vertebral unit (VU) was defined as the region between two virtual lines drawn through the middle of each vertebral body. RESULTS: Intraclass correlation coefficients were excellent-0.91 and 0.86 for the Gd-DTPA and STIR sequences, respectively. The overall correlation of the single MRI scores for both sequences was also good (r = 0.84, p = 0.01). The intrarater variance was 6.71 and 9.41 and the interrater variance was 13.16 and 19.04 for the Gd-DTPA and STIR sequences, respectively. The smallest detectable distance was 4.7 and 5.6 for the Gd-DTPA and STIR sequences, respectively. The concordance rate for both sequences was 83.5% (range 80.5-87.7% in the three spinal segments). Inflammatory spinal lesions were found in 10.1% of the VUs in the STIR sequence but not in the T(1)/Gd-DTPA sequence, while the T(1)/Gd-DTPA sequence showed inflammatory lesions in 6.4% of the VUs that were found normal by STIR. CONCLUSIONS: Both MRI techniques can evaluate active spinal lesions in patients with AS. More spinal lesions are detected by the STIR sequence, but the reliability between readings and readers is better for the Gd-DTPA sequence. The ASspiMRI-a is a reliable instrument for evaluating acute spinal changes in AS.

Inflammation in ankylosing spondylitis: a systematic description of the extent and frequency of acute spinal changes using magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging (MRI) is increasingly used to detect inflammation in the spine of patients with ankylosing spondylitis (AS). OBJECTIVES: To detect differentially the presence and extent of inflammation in the three spinal segments of patients with AS by MRI. METHODS: In 38 patients with active AS, acute spinal lesions were assessed by T(1) weighted, gadolinium enhanced, spin echo MRI (T(1)/Gd-DTPA) and short tau inversion recovery (STIR) sequences. MRI was quantified by the validated scoring system ASspiMRI-a. Acute spinal lesions were detected in the whole spine and in each spinal segment. One vertebral unit (VU) was defined as the region between two virtual lines drawn through the middle of each vertebral body. RESULTS: A greater number of inflammatory spinal lesions were found by the STIR sequence than by Gd-DTPA: inflammation was present in 30.6% of the VUs as assessed by STIR, compared with 26.8% of the same VUs assessed by T(1)/Gd-DTPA. Inflammation was found more commonly in the thoracic spine (TS) than in the cervical (CS) or the lumbar spine (LS) with both techniques. When STIR was used, spinal inflammation in the CS, the TS, and LS was detected in 10/38 (26%), 28/38 (74%), and 9/38 (24%) patients, respectively. The VU T7/8 was found to be the VU most often affected by both techniques (27.8% by T(1)/Gd-DTPA and 34.5% by STIR). CONCLUSIONS: Spinal inflammation is a common manifestation in patients with AS, and appears more frequently in the TS. The scoring system ASspiMRI-a can be used for evaluation of acute spinal changes in AS.

Magnetic resonance spectroscopy in clinical oncology.

The combination of magnetic resonance spectroscopy (MRS) and imaging (MRI) has led to mapping metabolites from normal and neoplastic tissue within the time limits of a routine study. MRSI (magnetic resonance spectroscopy imaging) detects metabolites that contain protons, phosphorus, fluorine, or other nuclei. The uniqueness of the information available in vivo and in a non-invasive manner encouraged radiologists and oncologists to apply MRSI in research and clinical practice. Both (1)H- and (31)P-MRS have revealed significant disturbances in amino acids, lipids, and phosphorus-containing metabolites within tumors. Phosphocreatine is often diminished in neoplasms compared to their primary host or surrounding tissues. However, the reduction of the compound does not appear to be closely correlated to the degree of malignancy. Moreover, abnormalities in (31)P spectra from neoplasms are shared by other disorders. Changes in high-energy phosphate levels almost invariably occur with radio- and chemotherapy of tumors. The spectroscopic alterations are often seen before any variations in tumor size and shape can be detected. However, opposite responses can be associated with the same clinical outcome. (1)H-MRS has been successfully used to quantify the extent of neuronal cell loss imposed on the brain during radiotherapy. Recently, MRSI was successfully integrated into radiotherapy planning in prostate cancer patients. (19)F-MRS opens access to artificially induced fluorocompounds such as 5-fluorouracil and its metabolites.

Lymph node diagnosis in oncologic imaging: a dilemma still waiting to be solved.

The recognition of lymph node involvement is still one of the most challenging topics of diagnostic radiooncology. Above size, shape and contours, the intrinsic architecture of the node, its vessels and its metabolic activity are assessed and used for diagnostic conclusions. Conventional ultrasound has a high sensitivity for detecting enlarged lymph nodes, whereas its specificity is moderate. Tumor-associated alterations of intranodal angioarchitecture are not specific enough to allow reliable differential diagnosis of lymphadenopathy by color-coded Doppler ultrasound. Power Doppler ultrasound improved distinction between inflamed, reactive and metastatic nodes. Computed tomography (CT) is most widely used to detect and characterize lymph nodes in regions unaccessible to percutaneous ultrasound. However, diffuse lymph node enlargement secondary to infectious or granulomatous diseases cannot be discriminated from metastases or systemic lymphoma. Positron emission tomography (PET) provides superior staging information, as it offers functional information on tissue activity and has better sensitivity and specificity than CT for revealing neoplastic foci. Dual modality scanners (CT + PET) aid precise localization of diseased lymph nodes and give unique information regarding the activity of residual tumor tissue. Magnetic resonance (MR) imaging is comparable to CT in identifying lymph nodes. However, even quantitative assessment of signal intensity does not permit reliable follow-up of disease activity. MR lymphography opens a new chance to avoid understaging due to microscopic tumor invasion and overstaging due to peritumoural inflammation. With the expansion of this and other advanced techniques the need for invasive lymph node diagnosis will lessen.