Biomedical subjects

P Held

Publications and source records attributed to P Held.

132 records · Page 8Linked to original sources

PubMedDate not supplied

Comparison of 2D and 3D MRI of the optic and oculomotor nerve anatomy.

A total of 30 healthy volunteers underwent magnetic resonance imaging (MRI) with T1 weighted (w.) 3D magnetization prepared rapid gradient echo (MP-RAGE), T2 w. 2D turbo spin echo (TSE) and T2* w. 3D constructive interference in steady state (CISS) sequences to evaluate the detectability of the optic, oculomotor, trochlear and abducens nerves. CISS yielded the best results for the trochlear and abducens nerve, MP-RAGE for the optic chiasm and tract. The optic and oculomotor nerves were very well detectable using both CISS and MP-RAGE without any statistically significant difference between the two.

Abducens Nerve↗

PubMedDate not supplied

MRI of the hypopharynx with provocative maneuvers.

The purpose of this study was to assess the validity of magnetic resonance (MR) functional images of the hypopharynx. Following T2-weighted spin-echo sequences during quiet respiration, contrast enhanced 2D-Turbo-FLASH sequences were obtained during Valsalva-maneuver, quiet respiration, A- and U-phonation, respectively. Tumor detection was clearly improved using functional MRI (sensitivity of 97.4%, specificity 83.3%, accuracy 95.5%) when compared with MRI during quiet respiration (sensitivity of 87.1%, specificity 33.3%, accuracy 80%). Rapid MR sequences such as 2D-Turbo FLASH allow functional imaging of the hypopharynx, thereby improving MR diagnosis of hypopharyngeal tumors.

Adult↗

PubMedDate not supplied

Correlation of 3D MRI and clinical findings in the patients with sensorineural hearing loss and/or vertigo.

The aim of the study was to correlate clinical and magnetic resonance imaging (MRI) (3D CISS and MP-RANGE) findings in patients with sensorineural hearing loss (SNHL) and/or vertigo. We found a high correlation of MRI and symptoms (17 out of 18 patients, 13 out of 13, respectively) concerning detectability of tumors and acute labyrinthitis. In the case of labyrinthine fibrosis, the correlation between clinical and MRI findings was lower. In conclusion, high-resolution MRI is very suitable in patients with SNHL or vertigo caused by tumors or acute labyrinthitis.

Adolescent↗

PubMedDate not supplied

[Transitory hip osteoporosis in magnetic resonance tomography].

Transient osteoporosis of the hip (a rare clinical picture which was difficult to diagnose up to now) shows a typical signal response in Magnetic Resonance Tomography. This enables diagnosis of the disease in a single investigation. In this way, unnecessary investigations can be avoided and therapeutic consequences can be implemented as soon as possible. Magnetic Resonance Tomography is also the most sensitive technique in order to describe the course of transient osteoporosis of the hip.

Adult↗

PubMedDate not supplied

Signal, contrast, and resolution in optimized PD- and T2-weighted turbo SE images of the knee.

OBJECTIVE: Signal and contrast behavior, delineation of anatomical details, and flow artifacts were compared in dual echo SE and turbo SE (TSE) sequences. Results were correlated with theoretical aspects of the TSE technique. MATERIALS AND METHODS: A TSE sequence (TR = 3,500 ms, TEeff = 19, 93 ms, ETL = 3) and a conventional SE sequence (TR = 2,500 ms, TE = 20, 70 ms) were applied to 64 patients with knee injuries. Signal intensities of anatomical structures were measured in regions of interest. Contrast and edge sharpness of menisci and posterior cruciate ligament were evaluated by three independent observers. RESULTS: The TSE sequence yielded similar signal and contrast behavior compared with SE. Visual evaluation revealed nearly equivalent contrast and edge sharpness of menisci and posterior cruciate ligament in proton-density (PD)-weighted TSE images. Contrast and edge sharpness of menisci were significantly lower in T2-weighted TSE images. Reduced flow artifacts were found in PD- and especially in T2-weighted TSE images. Differences between both techniques are interpreted, taking into account influence of TEeff, ETL, k-space trajectory, magnetization transfer effects, and J-coupling. CONCLUSION: The TSE sequence yielded good image quality in PD-weighted, but slightly inferior quality in T2-weighted, images, reducing the time of acquisition by 50%.

Adult↗

PubMedDate not supplied

Endonasal frontal sinusotomy in surgical management of chronic sinusitis: a critical evaluation.

Frontal sinusotomy was performed on 110 patients undergoing routine endoscopic endonasal ethmoidectomy and the minimum diameter of the frontal sinus neo-ostium was determined intraoperatively. A total of 82 patients could be subjected to follow-up and redetermination of the neo-ostium diameter 13 months later. A postoperative CT was scheduled in 62 cases. The average minimum diameter of the frontal sinus neo-ostium, measured intraoperatively, was 5.6 mm (0-11 mm). After completion of wound healing, 81% of the frontal sinuses could be explored by probing or even inspected by rigid endoscopy. The average minimum diameter of the neo-ostia determined postoperatively was 3.5 mm (0-11 mm). Patients exhibiting aspirin sensitivity or diffuse nasal polyposis showed a more pronounced scarred constriction of the frontal sinus access compared to other cases. Neo-ostia exceeding 5 mm intraoperatively were preserved with a considerably higher percentage than those with diameters of less than 5 mm. Radiologically, the fenestrated frontal sinuses frequently showed continued or even increasing mucosal congestion. No conclusive relationship was found to exist between such post-operative clouding and frontal sinus accessibility (endoscopy and/or probing) or patient complaints. The investigations confirm the safety and reliability of frontal sinusotomy in surgical management of chronic paranasal sinusitis. The mucosa of the frontal sinus often reacts to surgery in the form of persistent or even newly developing mucosal swelling to which a specific pathophysiological significance cannot always be attributed.

Adult↗