The current role of precision surgery in oligometastatic prostate cancer.

Oligometastatic prostate cancer (omPCa) is a novel intermediate disease state characterized by a limited volume of metastatic cells and specific locations. Accurate staging is paramount to unmask oligometastatic disease, as provided by prostate-specific membrane antigen-positron emission tomography. Driven by the results of prospective trials employing conventional and/or modern staging modalities, the treatment landscape of omPCa has rapidly evolved over the last years. Several treatment-related questions comprising the concept of precision strikes are under development. For example, beyond systemic therapy, cohort studies have found that cytoreductive radical prostatectomy (CRP) can confer a survival benefit in select patients with omPCa. More importantly, CRP has been consistently shown to improve long-term local symptoms when the tumor progresses across disease states due to resistance to systemic therapies. Metastasis-directed treatments have also emerged as a promising treatment option due to the visibility of oligometastatic disease and new technologies as well as treatment strategies to target the novel PCa colonies. Whether metastases are present at primary cancer diagnosis or detected upon biochemical recurrence after treatment with curative intent, targeted yet decisive elimination of disseminated tumor cell hotspots is thought to improve survival outcomes. One such strategy is salvage lymph node dissection in oligorecurrent PCa which can alter the natural history of progressive PCa. In this review, we will highlight how refinements in modern staging modalities change the classification and treatment of (oligo-)metastatic PCa. Further, we will also discuss the current role and future directions of precision surgery in omPCa.

Acoustic radiation contrast in MR images for breast cancer diagnostics--initial phantom study.

Acoustic radiation contrast in magnetic resonance images is an approach to visualize the changes in ultrasonic loss and viscoelastic changes of the sample with the resolution of a magnetic resonance imaging (MRI) system. By irradiating ultrasound (US) into a tissue-mimicking sample, a displacement along the US beam path caused by the acoustic radiation force is obtained. This displacement varies with the US intensity, the duration of irradiation, the US attenuation and the viscoelastic properties of the sample. US pulses of 2.5 MHz with a duration of 20 ms and an intensity of <17 W/cm(2) are used. An MRI sequence was programmed to produce images in which the magnitude of the displacement is visualized by gray value changes. In addition, a finite element simulation of the measurements was performed to demonstrate the feasibility of the method. Through examination of the measurements and the simulations, information about viscoelastic changes was achieved. In this work, measurements on different breast phantoms are presented.

[Prospective feasibility study of chest X-ray vs. thoracic MRI in breath-hold technique at an open low-field scanner]. / Prospektive Machbarkeitsstudie zum Vergleich von Röntgenübersichtsaufnahme und Thorax-MRT in Atemanhaltetechnik am offenen Niederfeldgerät.

PURPOSE: MR investigations using a breath-hold sequence at an open low-field MR had to be compared to chest X-rays in patients with a wide spectrum of cardio-thoracic pathologies. MATERIAL AND METHODS: 114 patients and three volunteers who actually received a chest X-ray due to different indications underwent triplanar breath-hold (17 - 20 s) True-FISP sequence using a 0.2 T low-field MR (Siemens Magnetom Open, TR/TE/alpha: 7.3/3.5/80 degrees, SD: 10 mm, Pixel: 2.81 x 1.41 mm) a mean of 5.1 (+/- 8.2) days later. RESULTS: Signal-to-noise ratio as basics for pattern recognition was 3.2 in nodule, 5.0 in infiltration, and 12.0 in effusion, and therefore True-FISP is usable for the detection of these findings. MRI demonstrated nodules (89 % vs. 57 %), infiltration (81 % vs. 71 %), pleural effusions (86 % vs. 75 %), pericardial effusions (100 % vs. 21 %) and pulmonary congestion (90 % vs. 80 %) clearly more frequently compared to chest X-ray. DISCUSSION: MRI of the lung has been implemented successfully at an open low-field MR system. Diagnostic safety and accuracy are at least comparable to those of chest X-ray. The lack of superimposition led to a major improvement in the detection of pericardial effusions and nodules, and an increase in identification of infiltration, pleural effusion, and pulmonary congestion.

[Differentiation of benign osteoporotic and neoplastic vertebral compression fractures with a diffusion-weighted, steady-state free precession sequence]. / Differenzierung osteoporotischer und tumoröser Wirbelkörperfrakturen mit einer diffusionsgewichteten steady-state free precession-sequenz.

PURPOSE: To evaluate the diagnostic accuracy of a diffusion-weighted, steady-state free precession (SSFP) sequence for the differentiation of acute benign osteoporotic and neoplastic vertebral compression fractures. METHODS: 85 patients with 102 vertebral compression fractures were examined with MR imaging using a spine array surface coil (Siemens, Vision, 1.5 Tesla). The following sequences were performed in sagittal orientation: T1-weighted spin echo (SE), short-tau inversion recovery (STIR) and a diffusion-weighted SSFP sequence (TR = 25 msec, diffusion pulse length delta = 3 msec). The SSFP images were evaluated qualitatively on a 5-grade scale from strongly hypointense to strongly hyperintense. Quantitative analysis was performed with region of interest measurements (ROI) and calculation of a bone marrow ratio. RESULTS: 60 fractures were due to osteoporosis and 42 fractures were caused by malignancy. "Hyperintensity" in a vertebral fracture on a SSFP sequence provided a sensitivity of 100 % and a specificity of 93 %. The positive predictive value was 91 %, the negative predictive value was 100 %. Quantitative analysis of the bone marrow ratio showed a statistically significant difference between the osteoporosis and the tumor group (p < 0.001). The mean value for the osteoporotic fractures was - 0.32 (SD 0.33) and + 2.07 (SD 1.37) for the tumor group. CONCLUSION: The SSFP sequence provides a high accuracy in the differentiation of benign osteoporotic and neoplastic vertebral compression fractures.

A fast magnetic resonance imaging technique for children with mediastinal lymphoma: work in progress.

BACKGROUND: Mediastinal lymphoma often presents as a large tumor at the time of diagnosis. Usually chest X-ray filming is the first imaging modality and it is used for routine follow-up during the course of the disease. A new and very fast MRI technique has been developed at our center as an alternative. Results in three patients with mediastinal lymphoma during a pilot study are promising. PROCEDURE: After diagnosis the above patients were additionally investigated in a 0.2 T low-field MR-scanner by a modified true FISP sequence (see text) with an acquisition time of 3.6-4.6 sec. Follow-up was performed by both, X-ray filming and MRI. After diagnosis the patients, again, had both X-ray filming and MRI investigation for follow-up: one patient 2, one patient 3, and one patient 5 times. Images were evaluated and compared by two pediatric radiologists. RESULTS: Total investigation times for radiography and MRI were comparable. The tumor was better visualized by MRI on seven of nine images and gave additional information about the structure and the localization of the tumor as well as concomitant problems such as pericardial effusion. CONCLUSIONS: True FISP MRI may prove to be a good alternative to X-ray filming in the diagnosis and follow-up of mediastinal lymphoma.

Detection of BOLD changes by means of a frequency-sensitive trueFISP technique: preliminary results.

A new method is introduced to detect magnetic field modulation arising from brain activation-induced BOLD effects. This approach uses a two-dimensional high-bandwidth, high-resolution conventional gradient-echo steady-state imaging sequence known as TrueFISP. The ability to visualize changes in oxygen saturation comes from the fact that the method is sensitive to the local field. As is well known, as the oxygen saturation changes so does the local field associated with the venous blood. We demonstrate that it is possible to visualize not only venous blood with this approach on a macroscopic level for major veins, but also to measure conventional oscillatory like signal changes during activated and resting states. Unfortunately, the method has two major drawbacks. First, a long TR is needed to maximize signal changes and, second, the field must be very well shimmed or numerous experiments need to be run to find the activation, as the signal response is sensitive to the starting frequency in the resting state. Nevertheless, these images can be compared directly with anatomical images collected with the same method without the need for distortion correction.

Low field thoracic MRI--a fast and radiation free routine imaging modality in children.

Radiography of the chest is the most frequently performed radiological examination in pediatric imaging. However, it is associated with the application of ionizing radiation. In order to avoid ionizing radiation in children a new and very fast MRI technique has been developed at our center as an alternative to the pediatric chest X-ray. 100 patients who had received a chest X-ray were additionally investigated in a 0.2 T low-field MR-scanner by a modified true FISP sequence with an acquisition time of 3.6-4.6 s for a coronal triple-slice scan. X-ray and MR images were independently evaluated and later compared by two pediatric radiologists. Total investigation times (door-to-door time) for X-ray and MRI were comparable. The signal-to-noise ratio for lung parenchyma was 4.6-7.3. Of 189 pathologic findings 165 were depicted on MR images as well as radiographs, 18 were noted on MRIs only, 6 on X-rays only. Overall kappa was 0.87. True FISP MRI may be a good alternative to conventional chest X-ray. The main advantages are: fast imaging free of ionizing radiation, easy performance, no need for special equipment, optional imaging in all 3 planes, good image quality, and a high diagnostic value.

MR lung imaging at 0.2 T with T1-weighted true FISP: native and oxygen-enhanced.

An inversion recovery true fast imaging with steady precession (FISP) pulse sequence was developed to carry out fast imaging of the lungs at 0.2 T. Using this sequence, oxygen-enhanced magnetic resonance (MR) lung imaging was performed on healthy volunteers. The lungs showed signal enhancement (11.7% +/- 3.8%) when breathing 100% oxygen. Using inversion recovery, true FISP at low field may prove promising for MR lung imaging.

Diffusion-weighted imaging of tumor recurrencies and posttherapeutical soft-tissue changes in humans.

The aim of this study was to examine soft tissue tumor recurrences and posttherapeutic soft tissue changes in humans with a diffusion-weighted steady-state free precession (SSFP) sequence. Twenty-four patients with 29 pathologies of the pelvis or the extremities were examined. The lesions were classified as follows: group 1, recurrent viable tumors (n = 10); group 2, postoperative hygromas (n = 7); and group 3, posttherapeutic reactive inflammatory muscle changes (n = 12). The sequence protocol in these patients consisted of short tau inversion recovery images, T2-weighted spin-echo (SE), pre- and postcontrast T1-weighted SE images and the diffusion-weighted SSFP sequence. The signal loss on diffusion-weighting was evaluated visually on a four-grade scale and quantitatively. The signal intensities were measured in regions of interest and a regression analysis was performed. Statistical analyses was performed utilizing the Student's t-test. The signal loss was significantly higher for hygromas and edematous muscle changes than for recurrent tumors (p < 0.001) indicating higher diffusion of water protons. The regression coefficient was -0.11 (mean) for tumors. Hygromas had a significantly higher signal loss than inflammatory edematous muscle changes (p < 0.01). The regression coefficients were -0.29 (mean) for hygromas and -0.22 (mean) for edematous muscle changes. The SSFP sequence seems to be a suitable method for diffusion-weighted imaging of the musculoskeletal system in humans. These preliminary results suggest that the signal loss and the regression coefficients can be used to characterize different types of tissue.

Diagnostic value of increased diffusion weighting of a steady-state free precession sequence for differentiating acute benign osteoporotic fractures from pathologic vertebral compression fractures.

BACKGROUND AND PURPOSE: Differentiating acute benign from neoplastic vertebral compression fractures can pose a problem in differential diagnosis on routine MR sequences, as signal changes can be quite similar. Our purpose was to assess the value of increasing the diffusion weighting of a diffusion-weighted steady-state free precession (SSFP) sequence for differentiating these two types of vertebral compression fractures. METHODS: Twenty-nine patients with 32 acute vertebral compression fractures caused by osteoporosis (n = 15) or malignancy (n = 17) were examined with a diffusion-weighted SSFP sequence, a T1-weighted spin-echo sequence, and a short-inversion-time inversion recovery sequence. The SSFP sequence was performed with increased diffusion weighting (delta = 0.6, 3.0, 6.0, and 9.0 ms). The signal intensities of the fractured vertebral bodies were rated on a five-point scale from markedly hypointense to markedly hyperintense relative to normal adjacent vertebral bodies. Quantitative analysis was performed by region-of-interest measurements and by calculating the bone marrow contrast ratio. Statistical analysis was performed with the Mann Whitney U test and Student's t test. RESULTS: At delta = 3 ms, the osteoporotic fractures yielded hypointense signal in seven cases, isointense signal in six, and hyperintense signal in two. The fractures showed a progressive signal loss with increased diffusion weighting, so that hypointensity was reached in all but one case. All metastatic fractures had hyperintense signal with delta = 3 and 6.0 ms. With delta = 9.0 ms, four fractures became isointense. CONCLUSION: Increasing diffusion weighting can reduce false-positive hyperintense osteoporotic fractures or make hypointensity more obvious in cases of osteoporotic fractures.

Optimization and evaluation of the signal intensity change in multisection oxygen-enhanced MR lung imaging.

The behavior of the signal intensity in MRI of human lungs was investigated during inhalation of pure oxygen. Nine volunteers were examined, five using a breath-hold and four using a non-breath-hold technique. Four coronal slices were acquired in each volunteer using an inversion recovery turbo spin-echo sequence. The inversion time of the sequence was optimized for maximum contrast. Breathing of pure oxygen and room air was alternated in the volunteers. Breath-hold and non-breath-hold cases were compared. Breathing pure oxygen lead to a statistically significant signal intensity increase (up to 18%) compared to breathing room air. In addition, T(1) maps were acquired during breathing 100% oxygen and room air. Inhalation of pure oxygen reduced the mean T(1) time of the lungs from 1280 (+/-85) msec to 1224 (+/-139) msec without breath-hold and from 1219 (+/-176) to 1074 (+/-92) msec with breath-hold. Therefore, an optimized sequence and measurement protocol provided significant signal intensity changes utilizing 100% oxygen. Magn Reson Med 43:860-866, 2000.

Assessment of cerebral gliomas by a new dark fluid sequence, high intensity REduction (HIRE): a preliminary study.

The purpose of this study was to assess the diagnostic potential of a new dark fluid sequence, high intensity reduction (HIRE) in the diagnostic workup of patients with cerebral gliomas. The HIRE sequence utilizes a very long T(2) value of the cerebrospinal fluid (CSF) to suppress its high signal contribution in T(2)-weighted imaging by a image subtraction technique. Fifteen patients with histologically confirmed cerebral gliomas were examined with T(2)-weighted fast spin-echo (FSE), T(1)-weighted SE, fast fluid-attenuated inversion recovery (FLAIR), and HIRE imaging using identical scan parameters. In patients with enhancing lesions, fast FLAIR and HIRE were added to the contrast-enhanced T(1)-weighted SE images. Images were analyzed in a qualitative and quantitative evaluation. In the qualitative analysis, lesion detection, lesion delineation, and differentiation between enhancing and non-enhancing tumor tissue were assessed in a two-reader study. For the quantitative analysis, lesion-to-background and lesion-to-CSF contrast and contrast-to-noise ratios were determined in a region of interest analysis. HIRE achieved a significant reduction of the CSF signal without losing the high gray-to-white matter contrast of T(2)-weighted sequences. In the quantitative analysis, the contrast ratios of the HIRE images were lower compared with the FLAIR images due to a relatively high background and CSF signal. After administration of contrast media, HIRE images presented a significant signal increase in enhancing lesions, which subsequently increased the contrast and contrast-to-noise ratios. In the qualitative analysis, both readers found all tumors clearly delineated on HIRE imaging. Compared with T(2)-weighted FSE, the tumor delineation with HIRE was better in nine patients, equal in four patients, and less in one patient. Compared with the FLAIR images, HIRE was rated superior in three patients, equal in nine patients, and inferior in another three patients. Delineation of the enhancing tumor parts was possible with HIRE in all patients. HIRE images had significantly fewer image artifacts than FLAIR images due to reduced inflow effects. The T(2)-based HIRE sequence presented is an alternative to the T(1)-based FLAIR sequence, with the advantage of better gray-to-white matter contrast and shorter measurement time. Due to the subtraction technique, signal intensities from tissues with relaxation times in the range T(2 WM) < < T(2) < T(2 CSF) are also gradually affected, corresponding to their T(2) values. With respect to this unwanted effect, an improvement in HIRE imaging will be possible by using a self-weighted subtraction algorithm. In a forthcoming study this concept will first be tested on appropriate phantom fluids.

[HIRE (high intensity reduction). New cerebrospinal fluid suppressed T2-weighted imaging sequence]. / HIRE (high intensity reduction). Neue liquorunterdrückte, T2-gewichtete Bildgebungssequenz.

PURPOSE: The HIRE sequence utilizes the very long T2 value of CSF to suppress its high signal contribution in T2-weighted imaging by an image subtraction technique. METHODS: To assess the diagnostic potential of a new dark fluid sequence HIRE (High Intensity REduction) in the diagnostic work-up, 20 patients with histologically confirmed cerebral gliomas were examined with T2-weighted FSE, T1-weighted SE, fast FLAIR and HIRE using identical scan parameters. In patients with enhancing lesions fast FLAIR and HIRE were added to the contrast-enhanced T1-weighted SE images. Images were analyzed in a qualitative and quantitative evaluation. In the qualitative lesion analysis, lesion delineation and differentiation between enhancing and non enhancing tumor tissue were by two readers. For the quantitative analysis lesion-to-background and lesion-to-CSF contrast and contrast to noise ratios were determined in an region of interest analysis. RESULTS: HIRE achieved a significant reduction of the CSF signal without loosing the high gray-to-white matter contrast of T2 weighted sequences. In the quantitative analysis, the contrast ratios of the HIRE were lower compared to the FLAIR images due to a relative high background and CSF signal. After the application of contrast media HIRE images revealed a significant signal increase in enhancing lesions, which subsequently increased the contrast and contrast-to-noise ratios. In the qualitative analysis, both readers found all tumors clearly delineated on HIRE imaging. Compared to T2-weighted FSE the tumor delineation with HIRE was better in nine patients, equal in four patients and less in one patient. Compared to the FLAIR images HIRE was rated superior in three patients, equal in nine patients and inferior in another three patients. Delineation of the enhancing tumor parts was possible with HIRE in all patients. HIRE images present significant less image artifacts than FLAIR images due to reduced inflow effects. CONCLUSIONS: The presented T2 based HIRE sequence is an alternative to the T1 based FLAIR sequence with the advantage of a better gray to white matter contrast and shorter measurement time. Due to the subtraction technique signal intensities from tissues with T2 relaxation times in the range between white matter and CSF are also partially affected depending on their T2 values. With respect to this undesired effect, an improvement in HIRE imaging will be expected by a self-weighted subtraction algorithm.

Combination of signal intensity measurements of lesions in the peripheral zone of prostate with MRI and serum PSA level for differentiating benign disease from prostate cancer.

The aim of this study was to predict the benign or malignant nature of a prostatic lesion by defining a threshold value of signal intensity ratio and a limiting value of serum prostate-specific antigen (PSA) in patients with elevated PSA level. Twenty-six patients with elevated PSA level and no hypoechogenic lesions at endosonography underwent MR imaging using an endorectal body phased-array coil at 1.5 T (Siemens Magnetom Symphony). A T2-weighted turbo-spin-echo (TSE) pulse sequence was applied in a transverse orientation. Two radiologists evaluated the images. In the presence of a pathological finding they defined regions of interest (ROI) in the suspicious pathological area of the peripheral zone and in muscle for reference. The quotient of the two ROIs was calculated and then correlated with the actual PSA level. Diagnosis was confirmed by prostate biopsy. Ten of 12 patients with quotients smaller than 4 showed cancer at histology. Nine of 12 men with cancer proven by biopsy had PSA levels higher than 10 ng/ml. A significant difference (p < 0.001) was found between the quotients of cancer and quotients of chronic prostatitis, fibrosis, or glandular atrophy. The accuracy of tumor differentiation of the method was 77%. Measurement of signal intensity quotients in the peripheral zone of the prostate in combination with knowledge of defined limits of PSA levels the technique could be helpful in detecting additional cancer areas for prostate biopsy. False-negative tumor results of standard sextant biopsy can be reduced. In men with high PSA values the method has a role in differentiating between patients who require prostate biopsy and those of clinical observation.

Diffusion-weighted MR imaging of bone marrow: differentiation of benign versus pathologic compression fractures.

PURPOSE: To evaluate the usefulness of diffusion-weighted magnetic resonance (MR) imaging of bone marrow for differentiating between benign and pathologic vertebral compression fractures. MATERIALS AND METHODS: Thirty patients with 39 vertebral compression fractures were examined with MR imaging. Diffusion-weighted MR imaging was performed with a steady-state free precession sequence in 22 acute benign osteoporotic and/or traumatic fractures and 17 pathologic compression fractures. Biplanar radiographs, T1-weighted spin-echo (SE) MR images, and short inversion time inversion-recovery (STIR) MR images were available for all patients. The signal intensity characteristics were analyzed qualitatively and quantitatively (bone marrow contrast ratios and signal-to-noise ratios) for all sequences. RESULTS: At diffusion-weighted MR imaging, all benign vertebral compression fractures were hypo- to isointense to adjacent normal vertebral bodies. Pathologic compression fractures were hyperintense to normal vertebral bodies. Benign vertebral fractures had negative bone marrow contrast ratios at diffusion-weighted imaging, whereas pathologic vertebral fractures had positive values (P < .001). The difference in bone marrow contrast ratios for benign and pathologic compression fractures at T1-weighted SE and STIR imaging was not significant (P > .01). CONCLUSION: Diffusion-weighted MR imaging provided excellent distinction between pathologic and benign vertebral compression fractures.

Diffusion-weighted MRI in transient global amnesia: elevated signal intensity in the left mesial temporal lobe in 7 of 10 patients.

Prompted by the findings of previous studies with positron emission tomography and single photon emission computed tomography, which demonstrated hypoperfusion or hyperperfusion in the left temporal lobe in isolated patients with transient global amnesia (TGA), we compared the sensitivity of diffusion-weighted (DW) magnetic resonance imaging (MRI) with that of conventional T1- and T2-weighted MRI in patients with TGA. Ten patients with the typical syndrome of a pure TGA were included in the study. For all patients, a coronal DW sequence, a steady-state free precession (SSFP) sequence, and conventional T1- and T2-weighted turbo spin-echo sequences were obtained. Seven of the 10 patients had elevated signal intensity in the left hippocampal region on DW MRI; moreover, 3 of these 7 patients exhibited bilateral signal abnormality in this sequence. All conventional T1- and T2-weighted images as well as all follow-up studies were normal. The signal elevation in DW MRI correlates with a decrease in the interstitial space and with cellular edema in the temporal lobe during TGA. The underlying pathomechanism causing this cellular edema cannot be clearly outlined using DW MRI. Our data are, however, compatible with spreading depression. This is the first study to show that DW MRI is a sensitive MRI method for evaluating TGA, especially in the early stage of the disease.

MR cisternography: a new method for the diagnosis of CSF fistulae.

The aim of this study was to compare a new MRI method for detecting the existence of cerebrospinal fluid (CSF) fistulae, i. e. MR cisternography, with CT cisternography. In a prospective study, 30 patients with post-traumatic CSF fistulae were examined. The MR examinations were performed with a 1.0-T whole-body MR system, using two T2(*)-weighted sequences, a 3D PSIF (time-inversed fast imaging with steady-state precession, FISP) and a 3D constructive interference steady-state (CISS) sequence. The results of MRI and CT cisternography were compared with the surgical findings. The sensitivity in detecting CSF fistulae with MR cisternography (PSIF: 89.9 %; CISS: 93.6 %) was higher than with CT cisternography (72.3 %). The sensitivity of CT cisternography at detecting CSF fistulae in patients with a size of dural lesion less than 2 mm or in patients with multiple dural lesions is significantly lower compared with the MR method. Although the localization of CSF fistulae always proved possible with MR cisternography, this could only be accomplished wih CT in 70 % of cases. The MR cisternography technique is a new examination method with a higher sensitivity for the detection of CSF fistulae than CT cisternography. The CISS technique is superior compared with PSIF and should be used in patients with high-flow CSF fistulas.

Comparison of transcranial sonography, magnetic resonance imaging, and single photon emission computed tomography findings in idiopathic spasmodic torticollis.

Various lines of evidence suggest that the basal ganglia and thalamus are involved in the pathogenesis of idiopathic dystonia, but unfortunately neuroradiological and pathological data are sparse and controversial. In this study, we have examined 10 patients with spasmodic torticollis by neuroimaging techniques, including transcranial sonography (TS; n = 10), conventional (n = 10) and diffusion-weighted (n = 5) magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT; n = 10), employing [123I]iodobenzamide (IBZM) as a ligand with a high affinity to the D2 receptor. In seven patients, TS showed small hyperechogenic lesions in the medial segments of the lentiform nucleus contralateral to the side of head deviation. In accordance with the site of TS abnormalities, diffusion-weighted MRI displayed a hyperintense lesion in only one patient, while standard MRI of this area was normal in all patients. SPECT revealed a slight but statistically nonsignificant reduction of IBZM tracer uptake in an area corresponding to the dorsal portions of the striatum in 9 of the 10 patients. TS findings support the hypothesis that structural alternations of the pallidothalamic circuit contralateral to the side of head deviation are involved in the pathogenesis of idiopathic spasmodic torticollis. TS may be more sensitive in detecting basal ganglia alterations than MRI.

[MR diagnosis of cerebrospinal fluid fistulas using a 3D-CISS sequence]. / MR-Diagnostik bei Liquorfisteln mit einer 3D-CISS-Sequenz.

PURPOSE: We compared a new MR method for diagnosis of CSF fistulas with CT cisternography. MATERIAL AND METHODS: In a prospective case study we examined 35 patients with posttraumatic CSF fistulas and compared the results with the intraoperative findings. The MR investigation was performed using a 1.0T whole body MR-system. We used a strongly T2*-weighted 3D-CISS sequence. The examinations were performed in prone position, in patients with severe CSF rhinorrhoea additionally in supine position. RESULTS: The sensitivity and specificity of the MR method (88.9% and 95.1%) is higher compared with CT cisternography (77.8% and 87.8%). The reason for the lower sensitivity of CT compared with MRI are complex fracture systems, involving several paranasal cavities in patients with false positive results in CT cisternography. Reasons for the lower specificity of CT cisternography are false negative results in patients with small dural lesions below 2 mm2. CONCLUSION: Using a new method MRI can detect CSF-fistulas. The MR method is superior to CT cisternography, is noninvasive, the administration of contrast and agent is no longer necessary.

Diffusion measurements in the ischemic human brain with a steady-state sequence.

RATIONALE AND OBJECTIVES: The authors evaluate the clinical usefulness of a diffusion-weighted steady-state free-precession (SSFP) sequence to detect acute and subacute ischemic changes. METHODS: Twenty-four patients were examined on a 1.5-tesla scanner, using a SSFP-sequence (repetition time [TR]/ echo time [TE] = 22/3-8 mseconds). The slice thickness was 5 mm, 10 averages, 57 seconds per slice. The diffusion gradient strength was 23 millitesla/m, with b-values from 165 to 598 seconds/mm2. Diffusion-weighted images (DWI) were compared with T2-weighted images. RESULTS: The diffusion-weighted SSFP sequence produced diagnostic quality images in 23 of 24 patients. Diffusion depicted (group 1: 0-12 hours) more acute lesions (3 of 6) than T2-weighted images (2 of 6); the mean lesion diameter depicted by diffusion was 10.9 mm (standard deviation [SD], 12.3) and in T2-weighted images was 4.7 mm (SD 6.8). A significant correlation (P < 0.017) in subacute lesions was found when diffusion was compared with turbo spin echo (mean size difference/T2 = 18.5/17.5 mm, SD 13.2/12.2). CONCLUSIONS: The diffusion-weighted SSFP-sequence is more sensitive in acute ischemia and delineates likewise in subacute ischemia, when compared with T2-weighted imaging.