A contrast correction method for dental images based on histogram registration

Contrast correction is often required in digital subtraction radiography when comparing medical data acquired over different time periods owing to dissimilarities in the acquisition process. This paper focuses on dental radiographs and introduces a novel approach for correcting the contrast in dental image pairs.The proposed method modifies the subject images by applying typical registration techniques on their histograms. The proposed histogram registration method reshapes the histograms of the two subject images in such a way that these images are matched in terms of their contrast deviation. The method was extensively tested over 4 sets of dental images, consisting of 72 registered dental image pairs with unknown contrast differences as well as 20 dental pairs with known contrast differences. The proposed method was directly compared against the well-known histogram-based contrast correction method.The two methods were qualitatively and quantitatively evaluated for all 92 available dental image pairs. The two methods were compared in terms of the contrast root mean square difference between the reference image and the corrected image in each case. The obtained results were also verified statistically using appropriate t-tests in each set.The proposed method exhibited superior performance compared with the well-established method, in terms of the contrast root mean square difference between the reference and the corrected images. After suitable statistical analysis, it was deduced that the performance advantage of the proposed approach was statistically significant.     

Mucocutaneous and peripheral soft-tissue hemangiomas: MR imaging

Hemangiomas are common congenital lesions that may have devastating sequelae. The extent and location of a lesion determines the therapeutic approach. We describe 11 patients with mucocutaneous or peripheral soft-tissue hemangiomas to illustrate the ability of magnetic resonance (MR) imaging to define clearly and noninvasively the extent and anatomic relationships of hemangiomas. The major advantage of MR imaging over computed tomography or angiography is the exquisite difference in contrast between hemangiomas and the surrounding structures on T2-weighted MR images, in which hemangiomas have a relatively intense signal. Hemangiomas demonstrated relatively low signal intensity (similar to muscle) on T1-weighted images, which were markedly inferior to T2-weighted images in defining the extent of the lesions. Phleboliths and feeding or draining vessels were rarely visible. The information obtained with MR imaging may be valuable clinically in planning surgical resection or laser therapy of aggressive lesions, in evaluating effectiveness of medical or embolic therapy, and in defining recurrence.     

Superficial peroneal nerve block for leg venography

Insertion of a needle into the dorsum of the foot for lower-extremity venography is painful for many patients, and several attempts at puncture may be necessary. A regional anesthetic technique, superficial peroneal nerve block, has been devised to alleviate this pain. The nerve block is simple to perform, consisting of infiltration of lidocaine just above the ankle. Discomfort from performance of the block was minimal in all 20 cases in which it was performed. The block was effective in eliminating or significantly reducing pain in 17 of the 20.     

A patient-reported comparison of trapeziectomy with Swanson Silastic implant or sling ligament reconstruction.

A retrospective review of two types of operations for carpometacarpal osteoarthritis of the thumb was done for patients operated on between 1991 and 1996. Follow-up ranged from 18 to 90 months (mean 62 months). Fifty-eight Swanson Silastic arthroplasties and 56 sling excision arthoplasties were reviewed. Eight patients with Swanson arthroplasties underwent removal of the implant. Eight patients in the sling excision group required further surgery. These patients were excluded from further analysis. Questionnaires about pain, general satisfaction and function were sent to the other patients and 87 responses were received (sling 45, implant 42). In the implant group significantly better results were obtained for pain at 1 year, carrying a milk bottle and taking a handbrake off a car, and overall function. We conclude that trapeziectomy combined with Swanson implant gives better results in the short term if there are no complications of the operation.     

高频超声评估弹簧韧带损伤

目的 评价高频超声诊断弹簧韧带内上支损伤的价值。方法 采用6~15 MHz线阵探头,对21例成人获得性平足症患者(平足症组)和30名正常志愿者(对照组)进行超声检查,观察弹簧韧带内上支声像图特征,测量和比较两组弹簧韧带内上支近端和远端厚度。结果 对照组弹簧韧带内上支超声表现为中低回声条索,结构清晰,韧带近端厚度为(4.19±0.57)mm,远端厚度为(3.81±0.77)mm;平足症组超声示弹簧韧带肿胀增粗,回声减低,结构不清晰,韧带近端厚度为(5.32±1.11)mm,远端厚度为(6.35±1.41)mm;两组韧带近端及远端厚度差异均有统计学意义(P均<0.05)。结论 高频超声诊断弹簧韧带损伤便捷、无创,可为平足症提供诊断和治疗依据。     

Does sleeping on a waterbed promote gastroesophageal reflux?

We conducted a randomized prospective study with extended intraesophageal pH monitoring on two consecutive nights to test the hypothesis that a waterbed (WB) might increase recumbent acid exposure compared to a regular bed (RB). We studied 10 controls (mean age 29 years; five males, five females) with no history of reflux symptoms more than two times per month. We also studied 10 reflux patients (mean age 42 years; seven males, three females) with symptoms at least five days a week and documented recumbent reflux, with or without upright reflux, by previous 24 hr pH study. A standard meal (56% fat) was provided at 6 pm. After randomization, the subjects and patients slept on the assigned bed (WB or RB) in one nearby hotel. The pH probe was removed the next morning at 8 am. On the same day, the pH probe was inserted at 4 pm and the routine was repeated with use of the other bed. No significant difference (P> 0.05; paired t test) was found between the regular bed and waterbed in any measurement of recumbent reflux. Our study does not support the hypothesis that greater recumbent reflux may occur when sleeping flat on a waterbed compared to a regular bed. It does not, however, absolutely refute the possible association of waterbed use with esophagitis, since elevation of the head of a waterbed is not possible.