["Lines and tubes" in neonatal intensive care patients]

BACKGROUND

Central catheters in neonatological intensive care patients are used for the prolonged application of medication or parenteral infusions. Dislocations and septic and thromboembolic complications may occur.

CONTROL OF POSITION

Radiologically, the correct position of the catheter must be proven. Dislocations or complications associated with central catheters must be diagnosed. For catheter monitoring plain film radiographs are the first line of investigation; however, sonography may be of additional assistance. Angiographic techniques should only be performed when conventional noninvasive methods do not supply satisfactory results. Special knowledge is necessary for monitoring catheters that are set via the umbilical artery or vein. The radiological applications for catheter monitoring in the neonate intensive care unit are discussed in this article.

[Chest X-ray of the neonate]

In diagnostic imaging of thoracic pathologies in mature and especially immature neonates, chest X-ray has a leading position. Profound knowledge of the normal chest X-ray and the potential physiological perinatal changes is the basic requirement for interpretation of the X-ray of a neonate. Childhood pathology: Many congenital and acquired diseases that the radiologist is faced with in neonatology are unknown in the imaging of adults. Many of these changes are life-threatening or may have an impact on the patient's future quality of life. Therefore early diagnosis in close cooperation with the paediatrician is essential. We give here an overview of the most important pathologic changes that the radiologist may be confronted with in daily routine.

In vivo development of brain phosphocreatine in normal and creatine-treated rabbit pups

To study the effects of creatine (Cr) on brain energy metabolism and on hypoxia-induced seizures, 5- to 30-day-old rabbit pups were given subcutaneous Cr (3 g/kg) for 3 days before exposure to 4% O2 for 8 min. In saline-treated controls, hypoxic seizures were most frequent at 15 days (80% of pups) and 20 days (60%) of age. Seizures were prevented at 15 days and reduced 60% at 20 days in Cr-treated pups. In surface coil-localized brain 31P nuclear magnetic resonance spectra, with signal from both cerebral gray (GM) and white (WM) matter, the phosphocreatine (PCr)/nucleoside triphosphate (NTP) ratio doubled between 5 and 30 days of age in controls. In all Cr-injected pups, brain PCr/NTP increased to values seen in 30-day-old controls. When spectra were acquired in predominantly GM and WM slices in vivo, the PCr/NTP ratio was very low in GM at 5 days but reached adult levels by 15 days in controls. In WM, the ratio increased steadily from 5 to 30 days of age. In Cr-injected pups, PCr/NTP increased to mature levels in WM and in GM at all ages. In conclusion, hypoxic seizures occur midway in the time course of brain PCr/NTP increase in rabbit pups as previously described in rat pups. In both altricial pups, systemic Cr increases brain PCr/NTP ratio and prevents hypoxic seizures. These results suggest that mature levels of PCr and/or Cr in brain limit EEG activation either directly or indirectly by preventing hypoxic metabolic changes.

The postoperative shoulder

Because disability and pain may persist or recur after shoulder surgery, visualization of the postoperative shoulder before further treatment is of great interest. Postoperative status is reevaluated most frequently after rotator cuff repair, capsulorrhaphy in patients with chronic instability, and acromioplasty, where postoperative symptoms are clinically difficult to distinguish from rerupture or inadequate surgical results. Postoperative evaluation or follow-up after surgical treatment of tumors or surgical repair of shoulder injuries are other potential indications. Whereas surgical procedures for osseous components primarily will be evaluated by plain film radiographs, magnetic resonance imaging is a valuable tool for other sites of surgical treatment, such as soft-tissue components, with further potential indication for magnetic resonance arthrography. This article focuses on normal and abnormal postoperative findings in the shoulder, with emphasis of magnetic resonance imaging, and discusses specific findings based on magnetic resonance arthrography.

Magnetic resonance imaging of the postoperative knee

Due to the recent development of arthroscopic techniques in meniscal surgery and anterior cruciate ligament reconstruction, an increasing number of postoperative patients are referred for a magnetic resonance examination of the knee because of recurrent injury. Contrary to the nonoperative patient, T2-weighted sequences and, in unequivocal cases, magnetic resonance arthrography play the most important role in the evaluation of a possible meniscal retear. In patients with anterior cruciate ligament reconstruction, the changes of the magnetic resonance appearance of the anterior cruciate ligament graft during the first year after surgery must be considered in the diagnosis of retears. Recent developments in articular cartilage defect repair and the possible role of magnetic resonance imaging in the follow-up are discussed.

Magnetic resonance arthrography (MRA) in the postoperative shoulder

To evaluate changes in capsular mechanisms and the labroligamentous complex with magnetic resonance arthrography (MRA) after shoulder surgery and to establish possible criteria for the expected post-operative appearance of the shoulder. MRA of the shoulder was performed in 16 patients, before and 6 months after undergoing arthroscopic surgery for recurrent unidirectional dislocation. MR studies were performed after application of a constant amount of contrast solution (2 mmol Gd-DTPA). Axial and coronal oblique T1-weighted images were obtained with and without fat suppression techniques. Anterior (a) and posterior (p) capsular distances were measured, and the p/a ratio was established. Capsule thickness, capsular leaking, estimation of the volume of the axillary recess, appearance of the glenohumeral ligaments, and evidence of labral lesions were compared on pre- and postoperative images. Mean anterior capsular distance (a) decreased from 9.73 +/- 1.03 mm preoperatively to 5.27 +/- 2.49 mm postoperatively, whereas dorsal capsular distance (p) increased from 6.13 +/- 2.36 to 8.93 +/- 2.37. The p/a ratio increased from 0.64 +/- 0.25 to 2.36 +/- 2.54 (p = 0.007). Capsular leaking was suspected preoperatively in seven patients, but was not evident postoperatively. Capsular thickness and the estimated volume in the axillary recess did not change significantly. Contrast extension into pre-existent labral tears (nine patients) decreased or were not evident postoperatively. Changes in the appearance of the glenohumeral ligaments were found in six patients. Changes in capsular distances might be indicative of a decreased capsular laxity and could be a valuable criterion in the evaluation of the postoperative shoulder. Postoperative follow-up of labral tears is demonstrated by a decrease in contrast extension into or under a tear. Reactive capsular thickening or scar tissue formation can be reactive or preexistent. Changes in ligaments might be secondary to surgery. MRA may be helpful in the reevaluation of patients with suspected recurrent instability.

Importance of subchondral bone to articular cartilage in health and disease

The almost absolute barrier to diffusion of nutrients between articular cartilage and subchondral bone does not exist. These anatomic regions represent a functional unit. Repetitive overloading in degenerative disease leads primarily to lesions in the subchondral region (including vessels), which in turn impede flow of nutrition to articular cartilage. As a result, in degenerative joint disease the subchondral region shows reactive enhanced vascularization and heightened metabolism with insufficient repair. In aging, however, vascularization and metabolism are decreased; no repair takes place. In many cases, MRI allows visualization of these subchondral abnormalities. It also demonstrates the basic similarities of degenerative osteoarthritis, osteochondritis dissecans, and avascular necrosis. These different entities may have the same basic etiology but with different disease severity.

Germicidal ultraviolet irradiation in air conditioning systems: effect on office worker health and wellbeing: a pilot study

OBJECTIVES

The indoor environment of modern office buildings represents a new ecosystem that has been created totally by humans. Bacteria and fungi may contaminate this indoor environment, including the ventilation systems themselves, which in turn may result in adverse health effects. The objectives of this study were to test whether installation and operation of germicidal ultraviolet (GUV) lights in central ventilation systems would be feasible, without adverse effects, undetected by building occupants, and effective in eliminating microbial contamination.

METHODS

GUV lights were installed in the ventilation systems serving three floors of an office building, and were turned on and off during a total of four alternating 3 week blocks. Workers reported their environmental satisfaction, symptoms, as well as sickness absence, without knowledge of whether GUV lights were on or off. The indoor environment was measured in detail including airborne and surface bacteria and fungi.

RESULTS

Airborne bacteria and fungi were not significantly different whether GUV lights were on or off, but were virtually eliminated from the surfaces of the ventilation system after 3 weeks of operation of GUV light. Of the other environmental variables measured, only total airborne particulates were significantly different under the two experimental conditions--higher with GUV lights on than off. Of 113 eligible workers, 104 (87%) participated; their environmental satisfaction ratings were not different whether GUV lights were on or off. Headache, difficulty concentrating, and eye irritation occurred less often with GUV lights on whereas skin rash or irritation was more common. Overall, the average number of work related symptoms reported was 1.1 with GUV lights off compared with 0.9 with GUV lights on.

CONCLUSION

Installation and operation of GUV lights in central heating, ventilation and air conditioning systems of office buildings is feasible, cannot be detected by workers, and does not seem to result in any adverse effects.

Collateral ligaments of the ankle: high-resolution MR imaging with a local gradient coil and anatomic correlation in cadavers

Findings at high-resolution magnetic resonance (MR) imaging of the lateral and medial collateral ligaments of the ankle were compared with findings in anatomic sections from cadavers. MR imaging of six cadaveric feet was performed with a newly developed local gradient coil and axial and coronal T1-weighted spin-echo sequences. Axial imaging provided optimum views of the anterior and posterior talofibular ligaments, the deep layers of the medial collateral ligament, and the tibionavicular ligament. Coronal imaging allowed complete visualization of the calcaneofibular, posterior talofibular, tibiocalcaneal, and posterior tibiotalar ligaments. In both imaging planes, differentiation of the deep and superficial layers of the medial collateral ligament was possible. Differentiation between the syndesmotic complex and the lateral collateral ligament was accomplished easily; in particular, differentiation of the posterior tibiofibular ligament from the posterior talofibular ligament was not difficult because of the differing insertions of these ligaments. The inhomogeneous appearance of the medial collateral ligament and the posterior talofibular ligament on MR images correlated with areas of fatty tissue on corresponding microscopic sections. High-resolution MR imaging with a newly developed local gradient coil allows excellent visualization of the lateral and medial collateral ligaments of the ankle.

Ligaments and tendons of the ankle. Evaluation with low-field (0.2 T) MR imaging

PURPOSE

To investigate the value of MR imaging using a low-field imaging unit (0.2 T) for the evaluation of ligaments and tendons of the ankle.

MATERIAL AND METHODS

Twelve ankle specimens were studied using low-field MR imaging (0.2 T). The Achilles tendon, the tibialis posterior tendon, and the lateral collateral ligaments were evaluated for the presence of degenerative changes and partial and complete tears. Visibility and overall image quality were analyzed by qualitative evaluation.

RESULTS

Low-field MR images of the 24 tendons were interpreted as normal in 11 cases, showing degenerative changes in 9 cases and a partial tear in 1 case. Visualization was regarded as not sufficient for a diagnosis in 3 cases. Of the 36 ligaments, 14 were regarded as normal while degenerative changes were seen in 5 cases and a tear in 2 cases. In 13 cases, no diagnosis could be established, and in 2 cases only a probable diagnosis was established. The best overall quality was obtained with the use of T1 spin-echo (680/20/4) and T2 multi-echo (3000/40/1) images.

CONCLUSION

Optimized protocols for examination of the ankle using low-field MR imaging may allow evaluation of the Achilles and tibialis posterior tendons, but these protocols may not be as useful for diagnosing ligamentous changes.

MRI visualization of proteoglycan depletion in articular cartilage via intravenous administration of Gd-DTPA

The effect of intravenous administration of gadolinium diethylenetriamine-pentaacetic acid (Gd-DTPA) on MR images was studied in vitro, using pathologic osteochondral specimens removed during surgery for total endoprosthesis, and in vivo, on a group of volunteers. In ex vivo specimens, lesions of different shape having lower T1 were detected which corresponded to areas with depleted proteoglycans found histologically. In vivo experiments on young volunteers showed that the time course of cartilage enhancement was different for different anatomies. The time for maximum enhancement ranged from 45 min for the ventral femoral condyle to 270 min for patellar cartilage.

Comparison of low field (0.2T) and high field (1.5T) MR imaging in the differentiation of torned from intact menisci

PURPOSE

To evaluate the usefulness of a low field MRI system (0.2T; Esaote, Biomedica) for the evaluation of meniscal tears with regard to anatomic site, and to compare the results with findings from a high field unit (1.5T; Siemens, Erlangen).

MATERIAL AND METHODS

MRI was performed in 25 patients in a low field (0.2T; Esaote, Biomedica), and a high field (1.5T; Siemens, Erlangen) MRI unit. The images were analyzed for the presence or absence of meniscal tears and the confidence of decision making. Results were further analyzed for the number of identical and unidentical findings on both imaging modalities. In seven patients, arthroscopy was performed and the findings compared with the results from MR imaging. Statistical analysis was performed by chi 2-test, Wilcoxon test and Friedman analysis.

RESULTS

Qualitative evaluation of the level of confidence in decision making was significantly superior on high field strength images. When comparing the evaluations from both image modalities in 21 of 25 patients (84%), the diagnosis concerning the presence or absence of meniscal tears was identical.

CONCLUSION

Although low field MR imaging might offer diagnostic potential concerning the presence or absence of meniscal tears, the level of confidence in decision making is significantly superior with high field strength imaging, probably reflecting the higher conspicuity of lesions from high field strength units.

Discrimination between fluid, synovium, and cartilage in patients with rheumatoid arthritis: contrast enhanced Spin Echo versus non-contrast-enhanced fat-suppressed Gradient Echo MR imaging

PURPOSE

The aim of this study was to compare fat-suppressed T1-weighted 3D-Gradient Echo (GE)-images and conventional T1-weighted contrast-enhanced SE images in the assessment of patients with rheumatoid arthritis in an attempt to improve discrimination of inflamed synovium, joint fluid, and cartilage.

PATIENTS AND METHODS

28 knee joints in 20 patients with rheumatoid arthritis were examined with a 3 D-GE-T1 weighted sequence with frequency-selective fat suppression (Flash 3D fat sat) and T1-weighted SE-sequences after intravenous gadolinium-containing contrast agent administration using a 1.5T system. Differentiation of cartilage, synovium, and joint effusion was assessed on both sequences qualitatively by two observers and quantitatively by signal intensity measurements.

RESULTS

Qualititative analysis revealed higher grading rates for cartilage/fluid differentiation with fat-suppressed T1-weighted GE images than contrast enhanced T1-SE images. Quantitative analysis by measurements of contrast-to-noise ratios revealed significantly higher rates for the Flash 3D fat sat with regard to cartilage/fluid discrimination, significantly higher rates for T1-SE post-contrast for cartilage/synovium discrimination, and significantly higher rates for T1-SE post-contrast for synovium/fluid discrimination.

CONCLUSION

3D-GE-imaging with fat-suppressed T1 weighted sequences allows sufficient differentiation of cartilage and joint fluid in patients with rheumatoid arthritis without application of contrast agents and may assist in monitoring disease progression and response to therapy. The higher contrast to noise ratios of cartilage/synovium and synovium/fluid on T1-SE images following administration of gadolinium-containing contrast agents may improve detection of disease activity.

Magnetic resonance imaging in hemophilic children: value of gradient echo and contrast-enhanced imaging

The purpose of this study was to determine the value of Gradient Echo imaging for the evaluation of cartilage (3D fatsat) and blood products (2D Hemoflash), and the use of contrast enhanced SE imaging for the evaluation of synovial changes, in comparison to the clinical evaluation of children with hemophilia A. We investigated 21 joints in 16 patients with evidence of hemophilia A (mean age 11.3+/-2.1 years). In all patients, clinical examination, plain film radiographs, and MR evaluation were performed magnetic resonance imaging (MRI) was performed by using sagittal T1 SE and T2 SE images, as well as 3D fatsat GE and 2D GE images. Axial and sagittal T1 weighted SE images were obtained before and after contrast application. Findings from the clinical examination and MR imaging, regarding the evaluation of blood, synovia, and cartilage were compared. Clinical examination revealed evidence of a bleeding episode in 12 joints (57.1%), whereas MRI revealed evidence of blood or blood products in 15 joints (71.4%). Clinical investigations, including bleeding scores, pain scores, and physical examination scores did not correlate with MR findings. Due to the MR findings in 6 of 16 patients, therapeutic management was changed from on demand to prophylactic therapy. MR imaging with gradient echo and contrast-enhanced sequences is more sensitive than clinical examination for the detection of blood products in children with hemophilia. Its ability to demonstrate potentially early stages of cartilage or synovial alterations might assist in therapy planning. Clinical scores might underestimate effects of hemophilia.

[MRI arthrography of the ankle joint]

Due to its superior soft tissue contrast conventional MRI is the imaging method of choice in the evaluation of ankle joint disorders. Conventional MR imaging can accurately demonstrate normal or acutely injured ligaments; however, in subacute and chronic injury joint fluid necessary for delineation of injured ligaments is absent and MR arthrography should be performed. MR arthrography uses the intraarticular injection of contrast material to distend the joint, yielding improved discrimination of intraarticular structures. This joint distension with MR arthrography is also helpful in the staging of osteochondritis dissecans, since in cases of unstable lesions tracking of contrast material into the interface can be more easily demonstrated. Finally, high contrast and joint distension by MR arthrography improves the detection of intraarticular loose bodies, which often require surgery. MR arthrography, although invasive, may provide additional information in various ankle joint disorders.

[MRI of the ankle joint. Comparison of the 1.0-T and the 0.2-T units]

PURPOSE

Comparison of ankle joint injuries with different MR systems and at different field strengths.

METHOD

Ten patients with acute ankle injuries were examined using mid-field (1.0 T) and dedicated low-field (0.2 T) MR units. Findings of ligamentous injury, sinus tarsi involvement, bone injury, and tendon injury were correlated.

RESULTS

There was no significant difference between mid- and low-field MR imaging for ligamentous injuries (chi 2 = 0.0395), sinus tarsi changes bone injuries (chi 2 = 0.0507; critical value = 5,991).

CONCLUSION

This study showed good agreement in pathological findings in ankle injury on mid-field and low-field MR imaging.

[Chronic diseases of the ankle joint]

The etiology of chronic diseases of the ankle joint comprises a wide spectrum including chronic inflammatory processes and chronic degenerative, tumorous and neuropathic processes, as well as some specific syndromes based on chronic changes of the ankle joint. Of the inflammatory processes, chronic juvenile arthritis (JVC) is the most common disease. However, also Reiter disease, psoriasis or chronic monoarthritid diseases such as gout, as well as granulomatous diseases (tuberculosis, sarcoidosis) and fungal infections, may affect the ankle joint in a chronic course. Chronic degenerative changes are usually secondary due to abnormal positioning of the joint constituents or repetitive trauma. Neuropathic changes, as frequently seen in the course of diabetes, present with massive osseous destruction and malposition of the articular constituents. Chronic osseous as well as cartilaginous and synovial changes are seen in hemophilic patients. Chronic traumatic changes are represented by pigmented villonodular synovitis (PVNS), and chondromatosis, both with a predilection for the ankle joint. Due to the possibilities of magnetic resonance imaging (MRI), diagnosis of chronic ankle changes includes chronic ligamentous, tendinous and soft tissue changes. With the use of MRI, specific syndromes can be defined which particularly affect the ankle joint in a chronic way, such as the os trigonum syndrome, the anterolateral impingement syndrome and the sinus tarsi syndrome. Nevertheless, plain film radiographs are still the basic element of any investigation. MRI, however, can be potentially used as a second investigation, saving an unnecessary cascade of investigations with ultrasound and CT. The latter investigations are used only with very specific indications, for instance CT for subtle bone structures and sonography for a limited investigation of tendons or evaluation of fluid. Particularly due to the possibilities of MRI and the development of special gradient-echo imaging or high-resolution coils, the investigation of the ankle joint still offers a wide spectrum of innovation for the next years, which is particularly enforced by the increasing demand for specific diagnosis of chronic diseases in orthopedic medicine.

Tibiofibular syndesmosis: high-resolution MRI using a local gradient coil

PURPOSE

Our goal was to correlate high-resolution MR images of the tibiofibular syndesmosis with anatomic sections.

METHOD

MRI was performed inside a local gradient coil on six cadaveric feet taped in 10-20 degrees dorsiflexion and 40-50 degrees plantar flexion by using axial and coronal T1-weighted SE sequences. After imaging, the specimens were frozen and sectioned into 3-mm-thick slices along the MR planes. Images were correlated with the anatomic sections.

RESULTS

MRI depicted the anatomy of the tibiofibular syndesmosis and surrounding structures. With the foot taped in dorsiflexion, axial imaging provided optimum views of the anterior, posterior, interosseous, and transverse tibiofibular ligaments. Coronal images allowed visualization of the entire course of the anterior, posterior, and transverse tibiofibular ligaments. The multifascicular appearance of the anterior tibiofibular ligament was best visualized in coronal sections. With the foot taped in dorsiflexion or in plantar flexion, it was possible to distinguish the posterior tibiofibular ligament and transverse tibiofibular ligament from the posterior talofibular ligament in all specimens.

CONCLUSION

High-resolution MRI using a local gradient coil provides excellent delineation of the ligaments of the distal tibiofibular syndesmosis.

[Diagnostic reliability of 0.2 Tesla dedicated MRI low-field strength equipment in traumatology]

Anatomical dedicated low-field-strength MR imaging (non-whole-body-systems) has been developed for examinations of the peripheral joints. It has several advantages compared to high-field-strength MR imaging (whole-body-systems). The dimensions are small, the noise is not as bad as in whole body systems and people do not suffer of claustrophobic attacks. However, our results of a prospective blinded study in 56 patients with three different kinds of peripheral joint injuries demonstrated that the 0.2 T dedicated system showed a significant lower rate of diagnostic accuracy compared to middle and high-field-strength MR imaging and scored with obvious lower image quality ratings.

Low-field magnetic resonance imaging (0.2 T) of tendons with sonographic and histologic correlation. Cadaveric study

RATIONALE AND OBJECTIVES

The authors evaluate the role of low-field strength magnetic resonance imaging (MRI) compared with sonography in the evaluation of degenerative changes of tendons, with histologic correlation, based on investigations of horse cadavers.

METHODS

Low-field MRI and sonography was performed in 42 hours specimens for the evaluation of tendons and ligaments. Magnetic resonance imaging included sagittal and axial T1-weighted, T2-weighted, and gradient echo images. Sonography and MR images were evaluated for degenerative changes or tears and the findings were correlated with the histologic results.

RESULTS

Using histologic findings as a gold standard, the accuracy for the sonographic evaluation was 65.9%, sensitivity was 16.7%, and specificity was 100%. The corresponding data for low-field MR imaging were 70.5% accuracy, 44.4% sensitivity, and 88.5% specificity.

CONCLUSIONS

Low-field MRI investigation allows more accurate staging of tendinous changes than sonography. It is more reproducible and potentially includes the advantages of the combined evaluation of bones, ligaments, and soft tissue.

Condensing osteitis of the clavicle: MRI

PURPOSE

Condensing osteitis of the clavicle is a rare benign disorder, seen exclusively in women and characterized by expansion and sclerosis of the medial end of the clavicle. The aim of this study was to evaluate the MR findings of this disorder.

METHOD

MR images, obtained in four patients with evidence of condensing osteitis of the clavicle based on plain radiographs and clinical symptoms, included pre- and postcontrast T1 SE sequences, T2 SE images, GE images.

RESULTS

MR images revealed consistent hypointense areas on T1-weighted SE images, corresponding to regions of clavicular sclerosis (n = 4). T2-weighted SE images showed signal characteristics ranging from low intermediate signal intensity in regions of sclerosis (n = 4). T2-weighted GE images revealed moderate to high signal intensity presumably related to bone marrow edema (n = 2). Contrast-enhanced T1-weighted SE images were characterized by mild to extensive intraosseous and periosseous enhancement of signal intensity (n = 2).

CONCLUSION

MRI in cases of condensing osteitis of the clavicle reveals variable findings perhaps indicative of different stages of activity in this disease.

MR imaging in shoulder trauma. Value of STIR images

PURPOSE

To determine the adequacy of MR standard protocols by analyzing conventional T1- and T2-weighted SE sequences, and to evaluate the usefulness of additional fat-suppressed (STIR) images in shoulder trauma.

MATERIAL AND METHODS

Paracoronal T1-weighted, T2-weighted, SE, and STIR images were obtained on a 0.5 T superconductive system in 25 patients with shoulder trauma. In a separate evaluation of T1/T2 images and a combined evaluation of T1/T2 SE- and STIR images, we compared the number of patients with evidence of Hill-Sachs lesions, bone bruises, and/or rotator-cuff lesions.

RESULTS

Compared to the combined evaluation of T1/T2 and STIR images, the separate evaluation of T1/T2 SE images revealed identical results for rotator-cuff lesions and Hill-Sachs lesions, but different results for the bone bruises in the area of the major tubercle.

CONCLUSION

Occult fractures of the major tubercle, indicated by areas of bone bruising, might be missed with MR using conventional SE images. We recommend the use of additional paracoronal fat-suppressed sequences in patients with clinically suspected lesions and equivocal findings on plain radiographs and on standard SE sequences.

MR imaging of the inner ear and cerebellopontine angle: comparison of three-dimensional and two-dimensional sequences

OBJECTIVE

The aim of the study was to compare the ability of three-dimensional (3D) T2-weighted turbo spin-echo and gadolinium-enhanced 3D T1-weighted gradient-echo sequences with two-dimensional (2D) T2-weighted turbo spin-echo and gadolinium-enhanced T1-weighted spin-echo sequences to reveal anatomic and pathologic structures of the inner ear and cerebellopontine angle.

SUBJECTS AND METHODS

Thirty-one patients underwent axial 2D T2-weighted turbo spin-echo and 3D T2-weighted turbo spin-echo MR imaging, axial and coronal 2D T1-weighted spin-echo MR imaging before and after i.v. injection of gadopentetate dimeglumine, and gadolinium-enhanced axial 3D T1-weighted gradient-echo MR imaging. The visualization of anatomic and pathologic structures on the different sequences was evaluated. Statistical analysis was performed from the data obtained from the visual evaluation of the anatomic structures on the different sequences. Signal-to-noise and contrast-to-noise ratios were calculated for the gadolinium-enhanced 3D T1-weighted gradient-echo and 2D T1-weighted spin-echo sequences, and statistical evaluation was performed.

RESULTS

The 3D sequences enabled excellent visualization of 94% of all evaluated anatomic structures, and the 2D sequences enabled excellent visualization in only 3% of these structures. Pathologic structures were revealed in all cases by one or both of the 3D sequences. Diagnosis in all patients could be made by using the combination of the 3D T2-weighted turbo spin-echo and the gadolinium-enhanced 3D T1-weighted gradient-echo sequences. However, the 2D sequences failed to show pathologic structures in three patients. We found a significant statistical difference for the visualization of anatomic structures with the 3D and 2D sequences (p < .0001) and no significant statistical difference for the signal-to-noise and contrast-to-noise ratios with the 3D T1-weighted gradient-echo and 2D T1-weighted spin-echo sequences.

CONCLUSION

The 3D sequences revealed anatomic structures significantly better than did the 2D sequences and showed pathologic structures considerably more often than did the 2D sequences in all patients. MR imaging of the inner ear and cerebellopontine angle performed with 3D T2-weighted turbo spin-echo and gadolinium-enhanced 3D T1-weighted gradient-echo sequences provided the most accurate imaging leading to diagnosis in cases of abnormality.