Quantitative analysis of MRI signal intensity as a tool for evaluating tooth pulp vitality.

OBJECTIVES: To assess whether it is possible to measure tooth vitality using magnetic resonance imaging (MRI). METHODS: Signal intensity measurements were conducted using T(1) and T(2) sequences at the region of interest in 211 teeth (35 patients). RESULTS: Clinical findings showed that 17.3% of the teeth were avital, whereas 82.7% were found to be vital. Neither the T(2) sequence nor the non-contrast-enhanced T(1) sequence showed significant differences between vital and avital teeth. However, the contrast-enhanced sequence and, in particular, a comparison of signal intensities between the non-contrast-enhanced T(1) sequence and the contrast-enhanced sequence showed a significant difference between vital and avital teeth. CONCLUSION: Contrast-enhanced MRI enables us to draw conclusions on pulpal perfusion in vivo.

High-resolution dental magnetic resonance imaging of inferior alveolar nerve responses to the extraction of third molars.

The objective of this study was to assess whether signal changes can be detected in the neurovascular bundle of the mandibular canal after the extraction of a third molar. We retrospectively analyzed MRI scans of 30 test subjects with healthy mandibles and 41 patients who had had a wisdom tooth extracted. Signal intensities were measured at particular sites in the neurovascular bundle, which were defined as regions of interest (ROI) in the sagittal T1-weighted images before and after intravenous administration of a paramagnetic contrast agent. On the basis of the signal intensity increases that were measured after contrast agent administration, we compared the signal increases obtained for the patients who had received surgical treatment with the results obtained for the population of test subjects with unremarkable mandibles ( t-test, P<0.05). Compared with the healthy test subjects, patients who had received surgical treatment showed significantly higher signal intensity increases at two measurement sites, i.e., the second molar and the second premolar ( P<0.05). We found no significant differences when the measurements were performed at the first molar ( P=0.06), the third molar ( P=0.47) and in the area of the ascending mandibular ramus ( P=0.79). Compared with a population of healthy test subjects, patients who had their third molars surgically removed show higher signal intensity increases in the neurovascular bundle after intravenous contrast agent administration. The underlying cause may be the higher blood flow in the arteries and veins and the perineural plexus, which may give evidence of the pathophysiological mechanism of nerve damage in the narrow canal as a result of osteotomy.

[Quantitative analysis of MRI intensity in of the major petrosal nerve in patients with idiopathic facial paralysis]. / Quantitative Analyse der MR-Signal-Intensität des N. petrosus major bei Patienten mit idiopathischer Fazialisparese.

The objective of this study was to evaluate signal intensity increases in the greater petrosal nerve after contrast agent administration to gather information on the etiology of idiopathic peripheral facial paralysis. Magnetic resonance images were obtained from 18 patients who received inpatient medical treatment for acute peripheral facial nerve palsy. Images of intratemporal segments of the facial nerve were taken with a slice thickness of 0.75 mm. After multiplanar reconstruction, regions of interest (ROI) were defined in the proximal segment of the greater petrosal nerve. After multiplanar reconstruction, it was possible to visualize the greater petrosal nerves of all 18 patients. The nerve's average diameter was found to be 0.68 mm (range 0.5-0.9). Signal intensity increased by an average of 50.3% (range -10-146%) after contrast agent administration. Whereas this intensity was slightly reduced in two patients, it was increased in 16. No correlation could be established between greater signal intensity and medical history, clinical condition, laboratory findings, or electrophysiological data. In contrast to quantitative measurements in the facial nerve, ROI measurements in the greater petrosal nerve do not correlate with medical history, clinical condition, or laboratory findings. For this reason, MRI of this nerve does not enable us to draw conclusions on the etiology of idiopathic peripheral facial paralysis.

Diagnosis of chondral lesions of the knee joint: can MRI replace arthroscopy? A prospective study.

The role of magnetic resonance tomography (MRI) for the diagnosis of chondral lesions of the knee joint is still unclear. The sensitivity of the method ranges from 15% to 96%. The scope of our daily experiences showed that there were considerable deviations between the tomographical and arthroscopical results, which vary from the results of experimental studies. Therefore we have conducted a prospective study to investigate the question of how MRI can replace arthroscopy (ASC) in the diagnosis of cartilage damages in the scope of daily routine. All 195 patients included in this study received a magnetic resonance tomography followed by an arthroscopy. A clear diagnosis of supposition had to be determined before the magnetic resonance tomography. The patients were divided into 3 Groups. Group A (n=86) received a standard Military Hospital Ulm (MH) MRI--sagittal STIR TSE and PD TSE, coronal and transversal T2 FFE (TR=660 ms, TE=18 ms, FA=30 degrees, 512 matrix). In addition, one sub-Group, AK (n=21) was examined with a special cartilage sequence of the cartilage fs T1 W FFE. Neither patients in Group AK nor in Group A as a whole received any contrast medium. Group B (n=88) was examined with an alternate MRI protocol (Radiological Joint Practice, Neu-Ulm--sagittal T1 SE, T2 SE and T2 FLASH (TR=608 ms, TE=18 ms, FA=20 degrees, 256 matrix), coronal PD fs), employing gadolinium as a contrast medium. 156 cartilage lesions were found arthroscopically. In Group A the sensitivity was 33%, the specificity 99%, and the positive and negative prediction values 75% and 98% respectively. Group B reached a sensitivity of 53% and a specificity of 98%. The positive prediction value was 48% and the negative was 98%. Group AK showed a sensitivity of 38% and specificity of 98%; the positive and negative prediction values came to 50% and 97% respectively. In conclusion, our results indicate that the MRI examination techniques recommended in the literature at present are not able to replace the ASC for the diagnosis of cartilage damages of the knee joint. In view of the high specificity (97%-99%) and the high negative prediction value (97%-98%), MRI is suitable for the exclusion of cartilage lesions. For a negative MRI associated with a cartilage injury, a cautious attitude towards an operative cartilage treatment is therefore justified. Because the MRI can not replace the ASC for diagnostic of cartilage damage, the ASC still has to be seen as the method of choice for the evaluation of cartilage damage.

[Quantitative analysis of contrast enhanced MRI of the inferior alveolar nerve in inflammatory changes of the mandible]. / Magnetresonanztomographische Signalanalyse im N. alveolaris inferior bei entzündlichen Veränderungen der Mandibula.

PURPOSE: To evaluate the role of contrast enhanced MRI in quantifying signal changes of the inferior alveolar nerve following inflammatory changes of the mandible. MATERIAL AND METHODS: 30 patients with inflammatory changes of the mandible underwent MRI of the face. Both sides of the mandible, the affected as well as the unaffected healthy side were evaluated retrospectively. Regions of interest were placed at 5 defined places on both sides to assess signal intensity before and after intravenous application of paramagnetic contrast agent. The results of the measurements were compared between the healthy and the affected side (t-test, p < 0.05) and correlated with clinical findings (t-test, p < 0.05). RESULTS: All patients with hypesthesia of the inferior alveolar nerve in areas of the lips or chin (n = 4) showed a marked increase in signal intensity from 35 % to 83 % distal to the inflammatory process. Patients without sensitivity disorders showed less increase in signal intensity with a maximum of 51 % distal to the inflammatory process. In nearly all patients no contrast enhancement was observed distal to the first molar on the unaffected side. CONCLUSIONS: Quantitative analysis of contrast enhanced MRI of the neurovascular bundle is able to show pathologic mandibular lesions. In case of inflammatory changes of the mandible the neurovascular bundle is able to show pathologic mandibular lesions. In case of inflammatory changes of the mandible, the neurovascular bundle shows a significant increase in signal intensity distal to the lesion compared to the unaffected healthy side of the mandible.

MR imaging of traumatic lesions of the inferior alveolar nerve in patients with fractures of the mandible.

BACKGROUND AND PURPOSE: The objective of this study was to assess whether MR imaging can image the neurovascular bundle in patients with fractures of the mandible. In addition, an attempt was made to evaluate whether MR images provide information regarding the continuity of the inferior alveolar nerve before surgery and regarding signal intensity changes after trauma. METHODS: We analyzed preoperative MR images of 23 patients with mandibular fractures. Object-oriented sagittal view proton density- and T1-weighted sequences (before and after the administration of contrast agent) were used not only in an attempt to obtain purely qualitative information regarding nerve continuity in the neurovascular bundle (inferior alveolar nerve, artery, vein) but also to perform quantitative region-of-interest measurements of signal intensities at four defined measurement sites. The measurements were compared with those obtained for a patient population with healthy mandibles. RESULTS: It was possible to interpret MR images in 21 cases. MR imaging findings showed that the neurovascular bundle had been cut in two patients and was intact in the remaining 19 patients. These MR imaging findings were confirmed intraoperatively in all cases. Although we found no significant signal intensity differences between patients with intact nerves and patients with cut nerves, we found significant differences between patients with mandibular fractures and patients with unremarkable mandibles. CONCLUSION: It is possible to diagnose the interruption of nerve continuity by using MR imaging. Signal intensity measurements in the neurovascular bundle provide no information regarding nerve continuity.

High-resolution MR technique allowing visualization of the course of the inferior alveolar nerve along cystic processes.

Magnetic resonance imaging is not established in the preoperative diagnosis of mandibular cystic lesions; therefore, no attempts have been made thus far to evaluate the course of the mandibular neurovascular bundle along the process. However, the radiologist can detect the neurovascular bundle along the cystic lesion by high-resolution MR imaging and convey this information to the maxillofacial surgeon. This reduces the risk of intraoperative damage of the nerve. The examination of the neurovascular bundle can easily be integrated in a tumor MRI protocol of the jaw if the slice orientation is adapted to the course of the mandibular canal.

[Topography of the inferior alveolar nerve in relation to cystic processes of the mandible in dental MRI]. / Lagebeziehung des N. alveolaris inferior zu zystischen Prozessen des Unterkiefers im Dental-MRT.

PURPOSE: Cystic processes are changing the course of the inferior alveolar nerve in the mandible. This study evaluates the possibility of demonstrating the relationship between space-occupying processes and the course of the neurovascular bundle. MATERIALS AND METHODS: Thirteen patients with cystic processes in the mandible (9 keratocystic lesions, 1 eosinophilic granuloma, 1 plasmocytoma, 2 adamantinomas) were examined by MRI (1.5-T magnet, 8-cm surface coil, PD-gradient-echo-sequences in sagittal and coronal orientation, without enhancement) and the results retrospectively evaluated. RESULTS: The entire course of the nerve could be delineated in all patients. In six patients with minor cystic processes, the nerve was identified in both sagittal and coronal orientation. In seven patients with major cystic lesions, only parts of the nerve were detected in either image orientation, but the nerve could be visualized in its entire length by evaluating coronal and sagittal images side by side. CONCLUSION: It is possible to delineate the inferior alveolar nerve in its entirety along pathologic mandibular lesions. For large cystic lesions, this requires the evaluation of both coronal and sagittal sections of multidirectional MRI.

[Comparison of the reliability of subjective evaluation and quantitative measurements of MR signal intensity in inflammations of the intratemporal facial nerve]. / Vergleich der Reliabilität von subjektiver Beurteilung und quantitativer Messung der MR-Signalintensität bei Entzündungen des intratemporalen N. facialis.

PURPOSE: To compare in a single-blind study the reliability of quantitative measurements and subjective evaluations of contrast enhancement of the facial nerve in patients with idiopathic facial paralysis. MATERIALS AND METHODS: Magnetic resonance images with a 0.7 mm slice thickness (surface coil) were obtained in patients with idiopathic facial paralysis before and after administration of Gd-DTPA, 0.1 mmol/kg. The five intratemporal segments of the facial nerve were quantitatively measured and subjectively assessed by five radiologists as to the degree of enhancement. The results were compared as to the reliability of both methods. RESULTS: Using the quantitative measuring method, 175 measurements were calculated from a total of 350 regions of interest. At all 35 measured sites, the five quantitative measurements produced identical results. In contrast, the subjective assessment of the five radiologists arrived at a majority consensus in only 16 sites. A complete agreement was not reached for any measured site. CONCLUSION: The measured quantitative increase in signal intensity after administration of contrast medium is more reliable than subjective assessment. The quantitative method enables reproducible signal intensity measurements even for different window settings and can be easily and swiftly performed at the workstation.

[MRI vs. arthroscopy in the diagnosis of cartilage lesions in the knee. Can MRI take place of arthroscopy?]. / MRT versus Arthroskopie bei der Diagnostik von chondralen Läsionen des Kniegelenkes. Kann die MRT die Arthroskopie ersetzen? Eine prospektive Studie.

INTRODUCTION: The accuracy of magnet resonance imaging in diagnosing cartilage lesions is discussed controversially. The sensitivity of this examination ranges from 15 % to 96 %. Clinical evidence demonstrates that cartilage lesions, diagnosed by MRI, were not confirmed in arthroscopy. The purpose of this prospective study was to analyse the practicability of replacing arthroscopy by MRI in diagnosis of cartilage lesions. PATIENTS AND METHODS: 195 patients with acute or chronic knee pain were examined by reason of a pathological clinic result by MRI preoperatively. In group A (n = 86), a standard program was performed in the radiological department of German Army Hospital (sagittal STIR TSE und PD TSE, coronary und transversal T2 FFE [TR = 660 ms, TE = 18 ms, FA = 30 degrees, 512er-Matrix]), in 21 patients (subgroup AK) a cartilage specific sequence (fs T1 W FFE) without gadolinium was added. Patients in group B (n = 88) were examined in a private outpatient clinic (sagittal T1 SE, T2 SE and T2 FLASH [TR = 608 ms, TE = 18 ms, FA = 20 degrees, 256er-Matrix]) with the use of gadolinium. A clear clinical diagnosis had to be performed before MRI examination. RESULTS: 156 lesions of the cartilage were detected arthroscopically. The sensitivity of the examination was in group A 33 %; group B 53 %; group AK 38 %, specificity in group A 99 %; group B 98 % and group AK 98 %. The positive and negative predictive values were in group A 75 %/98 %; group B 48 %/98 % and in group AK 50 %/97 %. CONCLUSION: MRI was not able to detect reliable cartilage lesions. Until now, arthroscopy is the golden standard to detect cartilage lesions.

Bell's palsy: what is the prognostic value of measurements of signal intensity increases with contrast enhancement on MRI?

Our objective was to assess the prognostic value of measurements of the degree of contrast enhancement of the intratemporal segments of the facial nerve. We prospectively obtained MRI, slice thickness <1 mm of 20 patients with a facial palsy on the first day of inpatient treatment, and measured contrast enhancement of the nerve. The data were compared with compound muscle action potential (CMAP) measurements and the clinical course. Analysis of the initial enabled differentiation of three patients whose palsy was to show no improvement from 17 whose palsy was to resolve as expected. No patient with a poor outcome showed lesser increase in signal in the internal auditory canal, pars tympanica and pars mastoidea than patients who fully recovered. In no patient who had been diagnosed on the basis of the initial MRI as having a "normal" palsy was the amplitude of the (CMAP) reduced to less than 20% that of the normal side. Measurement of contrast enhancement was thus shown to be a prognostic indicator and may provide a basis for a differential treatment of facial palsy.

[The prognostic value of quantified MRI at an early stage of Bell's palsy]. / Der prognostische Wert der dynamischen, kontrastmittelverstärkten Region-of-interest-MRT in der Akutphase der idiopathischen Fazialisparese.

OBJECTIVE: The aim of the study was to assess whether MRI has a prognostic value at an early stage of Bell's palsy. MATERIAL AND METHODS: Prospective, blinded study on 30 patients suffering from Bell's palsy, who came to hospital until the sixth day of illness, to receive high doses steroid therapy. MRI was done on the first day of inpatient treatment as a gradient-echo-sequence with a slice thickness of 0.7 mm before and after i. v. administration of 0.1 mmol GdDTPA/kg weight. The signal intensity increase was evaluated quantitatively by region on interest (ROI). The results were compared to the clinical outcome and the results of electrophysiology. RESULTS: The examinations of all patients could be evaluated. The 3 patients who developed a chronic facial paralysis were detected by MRI on the first day of inpatient treatment. The patients, who showed MR signs for an unfavorable course, had a highly significant pathologic compound muscle action potential (CMAP) as a result of the electrophysiologic measurement. Rather than using complex measurement procedures it is possible to obtain reliable prognostic information from just one measurement within the Internal auditory canal before and after i. v. administration of contrast. CONCLUSION: MRI has a prognostic value at an early stage of the illness. In the clinical setting this measurement is easy to perform, so that it is possible to obtain prognostic information at a stage when causal treatment is still possible.

Interferon-gamma in 5 patients with cutaneous radiation syndrome after radiation therapy.

BACKGROUND: Irradiation can cause acute inflammatory responses as well as chronic fibrotic alterations of the skin. Cutaneous radiation fibrosis evokes a complex of therapeutic problems. However, therapeutic options, apart from surgical approaches, are limited. PATIENTS AND METHODS: Five female patients suffering from severe cutaneous fibrosis were treated with interferon-gamma on a low-dose regimen, 3 x 100 microg/week subcutaneously for 6 months, then once per week for another 6 months. In 4 patients, skin thickness was measured with high-frequency (20 MHz) ultrasound in a clinically well-defined target skin lesion. In 1 patient, nuclear magnetic resonance imaging was performed to quantify the extent of cutaneous radiation fibrosis and to monitor the therapeutic outcome. RESULTS: All patients suffered from radiation-induced cutaneous fibrosis. Additionally, in 1 patient, a fistula, as assessed by lymph vessel scintigraphy, and in another patient a radiation ulcer was diagnosed. In all patients, reduction of radiation-induced fibrosis could be documented. Both fistula and radiation ulcer regressed completely under interferon-gamma therapy. CONCLUSION: Low-dose interferon-gamma therapy is a new and effective treatment modality for cutaneous radiation fibrosis caused by radiation therapy. The positive impact of interferon-gamma on our patients warrants randomized double-blind trials on therapy of radiation fibrosis.

The radiation accident in Georgia: clinical appearance and diagnosis of cutaneous radiation syndrome.

BACKGROUND: Eleven male Georgian soldiers were accidentally exposed to radiation by cesium 137 during their training in a military exercise camp in Lilo, Georgia between November 1996 and May 1997. OBJECTIVE: The characteristic sequelae of accidental cutaneous irradiation and available diagnostic methods are described. METHODS: Magnetic resonance imaging (MRI) of radiation ulcers was performed in all patients; thermography was performed in 2. In 7 patients ulcers and white macules were examined with high-frequency 20 MHz sonography; histologic results were obtained from all patients. RESULTS: Predominant lesions were radiation ulcers in 11 patients and white hairless macules in 7. MRI showed ulcers down to the muscles and an increase of signal intensity in the musculature in 9 cases. The corresponding muscle histology demonstrated vasculitis in 7 patients and necrosis in 2. In 2 patients, MRI signal intensity of the musculature was normal. In 3 patients, 20 MHz sonography showed dermal defects; 1 patient had cutaneous fibrosis. Thermography demonstrated hypothermic zones with extended inflammatory zones adjacent to the radiation ulcers in both patients examined. CONCLUSION: High-frequency 20 MHz sonography, MRI, and thermography are useful noninvasive methods for diagnosis of the extent of cutaneous radiation syndrome and for therapy planning.

[Recurrent pneumothorax after surgical resection treatment]. / Pneumothoraxrezidiv nach chirurgischer Resektionsbehandlung.

Between 1984 and 1994, 27 men and 4 women with primary spontaneous pneumothorax were treated surgically by excision of the bullae, without pleurectomy. The purpose of the present study was to establish by computed tomography (CT) of the lung whether the excision permanently eliminated the cause of pneumothorax. The median follow-up was 72 (21-127) months. There were two patients with recurrences (6.4%) who were operated on again. Sixteen of 31 patients had new blebs in the apex of the lung as documented by postoperative CT. The study indicates that simple excision of the bullous area cannot prevent the recurrence of blebs.

[Acute diagnosis of thoracic injuries of therapeutic relevance in severely injured and polytraumatized patients]. / Zur Akutdiagnostik therapierelevanter Thoraxverletzungen bei schwer- und polytraumatisierten Patienten.

PURPOSE: To determine the value of supine chest radiography in comparison to orientating chest CT in the initial diagnostic evaluation of severely polytraumatised patients. MATERIAL AND METHODS: 303 patients with primary indication for a cranial CT following trauma were investigated between 1988 and 1993. After performing the cranial CT all patients underwent a chest CT with an average of 6 CT slices without changing the position of the patient and with a median scan time of 4 minutes. The results of the chest CT were correlated with the findings of the supine chest radiography in regard to therapeutically relevant pathological changes. RESULTS: The sensitivity in detection of pneumothorax in supine chest radiography was 53% versus 97% in CT, atelectasis 20% versus 94%, lung contusion 79% versus 99%, haemotothorax 62% versus 97%. More fractures were found conventionally (sensitivity 94%) than by chest CT (sensitivity 44%). CONCLUSION: Supine chest radiography of polytraumatised patients is clearly inferior to orientating chest CT in demonstrating posttraumatic lesions; obtaining therapeutically relevant information justifies the additionally needed small amount of time.

[Radiographically demonstrable spinal changes in asymptomatic young men]. / Röntgenologisch nachweisbare Wirbelsäulenveränderungen asymptomatischer junger Männer.

PURPOSE: To find reliable data of the incidence of different variations of the spine. MATERIAL AND METHODS: Standardised radiographic examinations of 10,922 young, healthy pilot aspirants of the German air force were made. Radiographic examination included the whole spine in a.p. and lateral projection, the cervical spine in oblique projection and in a subunit of 5781 men the lumbar spine in oblique projection. RESULTS: The following incidences were found: mild habit scoliosis: 80.4%, structural scoliosis: 9%, severe thoracal kyphosis without severe lumbar lordosis: 5.1% and together with severe lumbar lordosis: 30.8%, mild forms of kyphosis of adolescence: 23.3%, severe forms: 2.1% and cuneiform deformation of vertebral body: 4.9%, sacralization: 7.8%, lumbarization: 5.9%, spondylolysis: 6.2%, spondylolisthesis: 4.3% and lumbar chondrosis: 2.1%. Chondrosis of the thoracal and cervical spine, osteochondrosis and coalescent vertebral bodies were found in less than 0.8% each. CONCLUSION: In only 2.6% were there no pathological findings. This shows importance of radiological spine examinations especially for industrial and preventive medicine.