Double inversion recovery imaging of the brain: initial experience and comparison with fluid attenuated inversion recovery imaging.

The purpose of this study was to evaluate the diagnostic efficacy of the double inversion recovery fast spin echo (DIR-FSE) sequence for brain imaging compared to the fluid-attenuated inversion recovery (FLAIR) sequence. DIR-FSE and FLAIR-FSE sequences were obtained and compared side by side. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, image quality, and artifacts. In addition, contrast ratios and contrast-to-noise ratios were determined. Scan time of DIR-FSE was 33% longer than scan time of FLAIR-FSE. Overall lesion conspicuity was equal on DIR-FSE and FLAIR-FSE; however, DIR-FSE showed particular advantages for infratentorial lesions and lesions with only poor contrast on T2-weighted images, whereas FLAIR was slightly superior for small superficial cerebral abnormalities. Gray-white differentiation was better with DIR-FSE. Cerebrospinal fluid suppression was equal on both sequences; cerebrospinal fluid pulsation artifacts were more pronounced on DIR-FSE but did not cause diagnostic difficulties on these images. We conclude that DIR-FSE might be obtained if infratentorial lesions and abnormalities with only slightly prolonged T2 relaxation times are suspected. Otherwise, FLAIR-FSE seems preferable.

Preoperative fast MRI of brain tumors using three-dimensional segmented echo planar imaging compared to three-dimensional gradient echo technique.

The purpose of this study was to compare the diagnostic efficacy of a newly developed T(1)-weighted three-dimensional segmented echo planar imaging (3D EPI) sequence versus a conventional T(1)-weighted three dimensional spoiled gradient echo (3D GRE) sequence in the evaluation of brain tumors. Forty-four patients with cerebral tumors and infections were examined on a 1.0 T MR unit with 23 mT/m gradient strength. The total scan time for the T(1) 3D EPI sequence was 2 min 12 s, and for a conventional 3D GRE sequence it was 4 min 59 s. Both sequences were performed after administration of a contrast agent. The images were analyzed by three radiologists. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, and image artifacts. In addition, signal-to-noise and contrast-to-noise-ratio (C/N) were calculated. The gray-white differentiation and C/N ratio of 3D EPI were found to be inferior to conventional 3D GRE images, but the difference was not statistically significant. In the qualitative comparison, lesion detection and conspicuity of 3D EPI images and conventional 3D GRE images were similar, but a tow-fold reduction of the scanning time was obtained. With the 3D EPI technique, a 50% scan time reduction could be achieved with acceptable image quality compared to conventional 3D GRE. Thus, the 3D EPI technique could replace conventional 3D GRE in the preoperative imaging of brain.

New approaches for imaging in gene therapy.

Gene therapy is increasingly used experimentally and clinically to replace defective genes and/or impart new functions to cells and tissues. With the recent advances in vector design, improvements in transgene and prodrug activation strategies, gene therapy has been applied to a wide variety of diseases, tissues and organ systems. It is now clear that our specialty will play a critical role in gene therapy research and its clinical applications. Three aspects of gene therapy are of particular interest to imaging. The first is in delivering genes and vector products by minimally invasive interventional techniques. The second is in quantitating gene and DNA deliveries, for example, by nuclear imaging. Finally, imaging can be used to monitor the levels of transgene expression in vivo. A variety of imaging techniques including PET imaging, nuclear imaging, MR imaging and optical imaging can potentially be used to achieve the latter. This brief introductory overview is intended to summarize current strategies and illustrate the role that radiology will play in this field.

New-born infants with severe hyaline membrane disease: radiological evaluation during high frequency oscillatory versus conventional ventilation.

OBJECTIVE: The aim of our study was to determine the impact of treatment with exogenous surfactant (ES) and high frequency oscillatory ventilation (HFOV) on the radiological appearance and clinical course of hyaline membrane disease (HMD) in new-born infants. MATERIALS AND METHODS: New-born infants (18) (median weight, 1010 g) with severe HMD (stages 3.5 and 4) who were treated with ES and HFOV were matched by birth weight and severity of disease with 18 new-born infants treated with ES and conventional mechanical ventilation (CV). Chest radiograms taken on days 1, 2/3, 4/5, 7, 14 and 28 were analyzed to check for the severity of generalized parenchymal opacities (GPO), local opacifications, pulmonary interstitial emphysema (PIE), gross air leak, general and localized overinflation, bronchopulmonary dysplasia (BPD) and clinical variables such as survival rates, duration of mechanical ventilation, mean airway pressure and inspired oxygen concentration. RESULTS: At 4 weeks of age, new-born infants treated by HFOV had less severe GPO (median degree 1.5 vs. 3), less PIE (1 vs. 7 patients) and fewer signs of BPD (median BPD degree 1.5 vs. 2.6). The incidence of pneumothorax and of local opacifications were similar in both groups. New-born infants on HFOV had a lower mortality rate (5 vs. 13), needed fewer days of mechanical ventilation (median 15 vs. 23 days) and lower inspiratory oxygen concentrations (median FiO2 0.38 vs. 0.64). CONCLUSION: In new-born infants with HMD, treatment with ES and HFOV resulted in a favourable radiological and clinical outcome as compared to treatment with ES and CV.

The value of MRI in silicone granuloma of the breast.

MRI can be a valuable technique in patients with silicone-granulomas to screen for cancers which are not visible on mammography and/or sonography.

[Imaging in parotid tumors: US versus MRT]. / Bildgebung bei Parotistumoren: US versus MRT.

27 patients, clinically suspected of having parotid tumours, were examined prospectively by sonography (high frequency linear array) and MRI (1.5 T, T1- and T2-weighted SE sequences before, and T1-weighted SE sequences after contrast). In 23 patients, 25 intraglandular tumours were demonstrated (two were multicentric); they consisted of 6 malignant parotid tumours, 11 pleomorphic adenomas, 7 cystadenolymphomas and one oncocytic adenoma. 4 patients had extraglandular tumours. All tumours were demonstrated by either method, but two extraglandular tumours were incorrectly diagnosed by sonography as being intraglandular and 8 tumours (28%) were not completely delineated by sonography. MRI localised the tumours correctly in all cases and demonstrated all lesions accurately, independent of their position or size. In summary, sonography appears suitable as the primary imaging method in the investigation of parotid tumours but in case of large, parapharyngeal or malignant tumours, MRI is clearly superior to sonography.

[Malignant and benign diseases of the breast in 41 male patients: mammography, sonography and pathohistological correlations]. / Maligne und benigne Erkrankungen der Brust bei 41 männlichen Patienten: Mammographie und Sonographie mit histopathologischer Korrelation.

AIM: The goal of our study was to evaluate findings in mammography and sonography in male patients with pathohistologically proven diseases of the breast. MATERIAL AND METHODS: Mammographies and sonographies, which were obtained in 41 male patients in a 6-year period, were retrospectively evaluated in accordance with the BI-RADS(R) classification. RESULTS: Histologically 13 carcinomas, 21 gynecomastias, 3 pseudogynecomastias, 2 epithelial inclusion cysts and 2 other benign lesions were diagnosed. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of mammography in differentiation of benign versus malignant disease were 92 %, 89 %, 80 %, 96 % and 90 %, respectively. Additional sonography did not change these results. However, sonography increased diagnostic confidence in 18.2 % (2/11) of suspicious lesions. CONCLUSION: In our study the invasive ductal carcinoma of male patients was a predominantly lobulated, ill-defined lesion in mammography and sonography. The differentiation of carcinoma to pseudogynecomastia and diffuse or dendritic gynecomastia was securely feasible. However, we could not reliably distinguish between carcinoma and some benign mass lesions. In cases of mammographically diagnosed masses or unclear mammography, additional sonography should be performed to increase the diagnostic confidence.

[Evaluation of a computer-assisted diagnosis system in breast carcinoma]. / Evaluierung eines computerassistierten Diagnosesystems in der Erkennung des Mammakarzinoms.

PURPOSE: Evaluation of a computerassisted diagnosis (CAD) system (R2 linage Checker 1.2). Comparison of the results of three readers with and without knowledge of the computer results. MATERIALS AND METHODS: The mammograms of 52 patients, bilaterally in two planes each, with histologically proven carcinoma of the breast were included in the study. They were first scanned by the CAD machine and subsequently read by three readers with different degrees of experience in two sessions with and without knowledge of the computer results. RESULTS: Of the 91 views of carcinomas, the readers detected 96%, 89%, and 85%, respectively. With CAD, the values rose to 97%, 93%, and 96%. The increase of the first observer was not significant. As for the 49 areas of malignant microcalcifications, the first reader showed a significant decrease of sensitivity, the other two readers showed no significant change. The sensitivity of CAD was 74% for masses and 86% for microcalcifications at a rate of 1.8 false positive markers per image. All but two tumors were correctly marked in at least one plane. CONCLUSIONS: Use of the CAD machine led to a significant increase of sensitivity in the detection of malignant masses by two of three observers. In the case of malignant microcalcifications, and for the most experienced observer, CAD did not improve the results. The most important problem is the high rate of false positive markers.

Update on imaging techniques of the wrist and hand.

Several imaging techniques are available and necessary for evaluation and treatment of hand and wrist pathology. Conventional radiography is still the imaging technique of first choice for evaluation of abnormalities of the wrist and hand. Bone scintigraphy is an important diagnostic tool with a high sensitivity but low specificity. Arthrography should be performed if abnormality of ligamentous or triangular fibrocartilaginous pathology is suspected; however, using arthrography, all three major compartments and both wrists should be examined arthrographically. In selected cases, such as occult fractures, fracture healing, and early detection of avascular necrosis, advanced imaging techniques, such as magnetic resonance imaging and computed tomography, may be necessary and are helpful to achieve correct diagnosis.

Thoracic venous anatomy delineated by malpositioned central venous catheters on plain chest films.

The aim of this essay was to demonstrate the thoracic venous anatomy as delineated by malpositioned central venous catheters on plain chest radiographs. We therefore used the didactic advantage of clinically inadvertent catheter positions. This approach was chosen to illustrate venous anatomy with plain chest radiographs, and, thereby, to recognize malpositions promptly on the modality with which positions of central venous catheters is routinely performed.

[Lymph node staging and diagnostic imaging--status quo and future prospects]. / Lymphknotenstaging und Bildgebung--"Status quo" und Zukunft.

Exact lymph node staging is crucial to tumor staging and outcome, as well as therapy planning. Due to the low specificity and sensitivity of current imaging methods, invasive, expansive and uncomfortable diagnostic procedures are still widely used, often in conjunction with imaging. This brief overview is intended to summarize current imaging strategies and to give an outlook on new experimental imaging strategies which may play an important role in lymph node staging.

["Tubes and lines" in thoracic radiography: malpositioning and complications]. / "Tubes and Lines" im Thoraxröntgenbild: Fehlpositionen und Komplikationen.

Chest radiography is essential to evaluate the placement and position of tubes and lines in patients treated in intensive care units, such as central venous and arterial catheters, endotracheal and nasogastric tubes, thorax drains, cardiac pacemakers and defibrillators. Radiologic findings with respect to normal positioning, wrong positioning, and complications are described and illustrated.

[Molecular imaging]. / Molekulare Bildgebung.

The disclosure of the human genoma, the progress in understanding of diseases on molecular and cellular levels, the discovery of new disease-specific targets, and the development of new medications will revolutionize our understanding of the etiology and the treatment of many disease entities. Radiologists are faced with a paradigm shift from unspecific to specific molecular imaging techniques as well as with enormous speed in the development of new methods and should be enrolled actively in this field of medicine.

[Experimental and clinical approaches to lymph node imaging]. / Experimentelle und klinische Ansätze zur Lymphknotenbildgebung.

Exact assessment of lymph nodes is crucial to tumor staging, choice of therapy and in predicting the outcome. Although imaging plays a central role in the evaluation of lymph nodes, current imaging methods have low sensitivity and specificity primarily because they rely on insensitive morphological criteria or because they have low special resolution. Because of this diagnostic dilemma invasive, expansive and uncomfortable diagnostic techniques and/or unnecessary aggressive therapies are still in use. This brief overview is intended to summarize current imaging strategies and to give an outlook on experimental and clinical strategies in lymph node imaging in cancer.

[Contrast optimization in CT angiography]. / Bolusoptimierte CT-Angiographie.

This paper compares different contrast injection techniques for optimizing vessel contrast in CT angiography (CTA). The optimal vessel contrast shall be defined as constant strong enhancement confined to the scanning interval. This "plateau enhancement" guarantees high-quality CTA images and should therefore be approximated during every CTA examination by an appropriate contrast injection protocol. With well-established injection techniques such as the standard bolus technique (constant uniphasic contrast bolus for all patients) or adjustment of the scan delay, considerable individual differences in the arterial enhancement can be observed, and a nondiagnostic examination or an inefficient use of contrast agent might be the result in a particular patient. Therefore, two sophisticated mathematical models have recently been developed for analyzing the individual enhancement characteristics. These models can be exploited to predict the arterial enhancement for any given intravenous contrast bolus in any patient and to optimize the contrast bolus in order to approach the ideal "plateau enhancement." These techniques have to prove their effectiveness in larger clinical series.

[Trauma of the facial bones and skull]. / Trauma des Gesichtsschädels und der Schädelkalotte.

Facial trauma is frequent and mainly caused by motor vehicle accidents. Due to this main etiologic factor, trauma to the facial skeleton is often associated with serious injuries, commonly involving the brain, chest or abdomen. As a consequence, the initial clinical management of these patients includes control of hemorrhage and immediate assessment of life-threatening injuries, including the maintenance of the airways. Patients presenting with facial trauma are initially evaluated with a systematic clinical examination because many fractures can be accurately diagnosed by inspection and palpation alone. In these cases plain film radiographs serve only for confirmation and documentation of the diagnosis. In many other cases accompanying and extensive soft tissue swelling may clinically obscure fractures. A complete and accurate evaluation of these patients requires additional radiological imaging methods. A series of plain films may be generally sufficient but in most of the cases they can be regarded as initial screening methods for more thorough diagnosis with computed tomography (CT). In trauma patients CT is the imaging method of choice because it shows more fracture lines and displaced fragments than any other imaging modality. CT delineates soft tissue and bony structures and can localize and even characterize foreign bodies. A complete and accurate characterization of the fracture type and potentially associated complications in mandatory for the appropriate treatment and can only be achieved by careful radiological (CT) evaluation.

[Temporal bone trauma and imaging]. / Schläfenbeintrauma und Bildgebung.

Fractures of the temporal bone result from direct trauma to the temporal bone or occur as one component of a severe craniocerebral injury. Complications of temporal trauma are hemotympanon, facial nerve paralysis, conductive or sensorineur hearing loss, and leakage of cerebrospinal fluid. Early recognition and an appropriate therapy may improve or prevent permanent deficits related to such complications. Only 20-30% of temporal bone fractures can be visualized by plain films (7). CT has displaced plain radiography in the investigation of the otological trauma because subtle bony details are best evaluated by CT which even can be reformatted in multiple projections, regardless of the original plane of scanning. Associated epidural, subdural, and intracerebral hemorrhagic lesions are better defined by MRI.

Power Doppler versus color Doppler imaging in renal allograft evaluation.

The purpose of this study was to evaluate the impact of PDS compared to conventional CDI in the followup of 72 renal allograft patients. Renal allograft vascularization, assessed by PDS and CDI, was scored from 0 to 4, where 0 was the cortical "blush" and 4 was residual central perfusion. These scores were correlated with the resistive index, serum creatinine levels, hematocrit, and, in 35 cases, biopsy results. PDS scores of renal perfusion were one grade lower than CDI scores in 59 of 72 patients and two grades lower in two of 72 patients. A statistically significant correlation was found between PDS scores and the RI (r2 = 0.6, P < 0.05). However, no significant correlation was found between PDS scores and creatinine levels or hematocrit values. PDS scores are not related to histologic findings in renal allograft dysfunction. Overall, five biopsy-related arteriovenous fistulas were detected, two of which were missed on the initial PDS examination. In conclusion, PDS provides more complete visualization of the renal allograft vessel tree than CDI. However, biopsy-related arteriovenous fistulas are better seen by CDI.

Five phase bone scintigraphy supports the pathophysiological concept of a subclinical inflammatory process in reflex sympathetic dystrophy.

This study evaluates quantitative and qualitative patterns of bone scintigraphy and correlates them to laboratory findings and clinical signs to reveal possible inflammatory reactions in RSD. Activity ratios between the affected hand/foot and the contralateral side were calculated in 99mTc DPD-bone scintigraphy for five phases (arterial: 0-30 sec, early blood pool: 0.5-5 min. late blood pool: 5-15 min, 3 hrs early bone, 24 hrs late bone phase) and the presence of five scintigraphic signs in the bone phases was assessed. Activity ratios of all phases correlated with ESR those in the early and late bone phase correlated with alpha 2 globulin and beta globulin concentrations and those in the arterial, the early and late blood pool phase with the gamma globulin concentrations, respectively. Clinical features such as pain, swelling, physical force, temperature differences and the duration of symptoms did not correlate to the activity ratios. However, three signs in the bone phase were negatively correlated to albumin concentrations. Positive correlations were found for alpha 2, gamma globulin concentrations, ESR, neutrophil cell counts and individual uptake patterns. We conclude that the quantitative analysis of five phase bone scintigraphy in RSD reveals different aspects of tracer kinetics and provides different pathophysiological information. Lateralization of regional hyperemia, increased micro vascular permeability and bone metabolism in RSD parallels shifts in protein concentrations and blood cell counts that are suggestive of a subacute inflammatory process, even in patients with no overt signs of inflammation.