Early magnetic resonance imaging compared with bone scintigraphy in suspected scaphoid fractures

We evaluated 100 consecutive patients with a suspected scaphoid fracture but without evidence of a fracture on plain radiographs using MRI within 24 hours of injury, and bone scintigraphy three to five days after injury. The reference standard for a true radiologically-occult scaphoid fracture was either a diagnosis of fracture on both MRI and bone scintigraphy, or, in the case of discrepancy, clinical and/or radiological evidence of a fracture. MRI revealed 16 scaphoid and 24 other fractures. Bone scintigraphy showed 28 scaphoid and 40 other fractures. According to the reference standard there were 20 scaphoid fractures. MRI was falsely negative for scaphoid fracture in four patients and bone scintigraphy falsely positive in eight. MRI had a sensitivity of 80% and a specificity of 100%. Bone scintigraphy had a sensitivity of 100% and a specificity of 90%. This study did not confirm that early, short-sequence MRI was superior to bone scintigraphy for the diagnosis of a suspected scaphoid fracture. Bone scintigraphy remains a highly sensitive and reasonably specific investigation for the diagnosis of an occult scaphoid fracture.     

The distal biceps tendon: footprint and relevant clinical anatomy

PURPOSE: There is little information in the literature describing the anatomy of the biceps tendon insertion. The purpose of this study was to map the footprint of the biceps tendon insertion on the bicipital tuberosity and to report on the relevant anatomy to assist surgeons with correct tendon orientation during surgical repair. METHODS: Fifteen fresh-frozen adult upper extremities were used in this study. The relationships between the long head of the biceps tendon, the short head of the biceps tendon, the muscle bellies, and the distal tendon orientation were examined. The length, width, and area of the biceps tendon insertion were measured. RESULTS: In all specimens examined, the biceps musculotendinous unit rotated 90 degrees externally from origin to insertion. The long head of the distal tendon was inserted onto the proximal aspect of the bicipital tuberosity, while the short head of the distal tendon was inserted onto the distal aspect of the tuberosity. The lacertus fibrosus, in all specimens, originated from the distal short head of the biceps tendon. On average, the biceps tendon insertion started 23 mm distal to the articular margin of the radial head. The average length of the biceps tendon insertion on the tuberosity was 21 mm, and the average width was 7 mm. The average total area of the biceps tendon insertion (footprint) was 108 mm(2). The average area of the long head of the biceps tendon insertion was 48 mm(2), and the average area of the short head of the biceps tendon insertion was 60 mm(2). CONCLUSIONS: Landmarks have been identified that will allow anatomic orientation of the distal biceps tendon during operative repair. The distal short head of the biceps tendon has a consistent relationship with the lacertus fibrosus and a distinct insertion on the bicipital tuberosity. The dimensions of the distal biceps tendon footprint have been determined to assist with bone tunnel or suture anchor placement during surgical repair.     

The anatomy of the bicipital tuberosity and distal biceps tendon

The anatomy of the distal biceps tendon and bicipital tuberosity (BT) is important in the pathophysiology of tendon rupture, as well as surgical repair. Understanding the dimensions of the BT and its angular relationship to the radial head and radial styloid will facilitate surgical procedures such as reconstruction of the distal biceps tendon, radial head prosthesis implantation, and reconstruction of proximal radius trauma. We examined 178 dried cadaveric radii, and the following measurements were collected: radial length, length and width of the BT, diameter of the radius just distal to the BT, distance from the radial head to the BT, radial head diameter, width of the radius at the BT, radial neck-shaft angle, and styloid angle. Furthermore, the morphology of the BT ridge was defined as smooth (absent), small, medium, large, or bifid. Of the specimens, 48 were further analyzed with a computed tomography scanner at the level of the BT to determine the distance to traverse both the anterior and posterior cortex and the anterior cortex alone. Eighteen fresh-frozen cadaveric elbows were dissected, and the insertion footprint of the distal biceps tendon was defined. The BT has a mean length of 22 +/- 3 mm and a mean width of 15 +/- 2 mm. The tendon insertion footprint is a ribbon-shaped configuration on the most ulnar aspect of the BT, and it occupies 63% of the length and 13% of the width of the BT. The BT ridge is absent in 6% of specimens and bifid in 6%, and the remaining 88% of specimens have a single ridge that may be classified as small, medium, or large. The mean diameter of the radial head is 22 +/- 3 mm. The mean radial neck-shaft angle is 7 degrees +/- 3 degrees , and the mean BT-radial styloid angle is 123 degrees +/- 10 degrees . None of the measurements correlated with patient age, sex, or race. We concluded that the morphology of the BT ridge is variable. The insertion footprint of the distal biceps tendon is on the ulnar aspect of the BT ridge. The dimensions of the radius and BT are applicable to several surgical procedures about the elbow.     

肱二头肌远端肌腱的解剖学研究及其临床意义

[目的]描述并测量肱二头肌远端肌腱的形态学特点及解剖学数据,为肱二头肌远端肌腱损伤的临床诊疗提供参考.[方法]在13具成人尸体标本上(男8具,女5具;26只肘关节)解剖观察肱二头远端肌腱的形态走行,并测量肱二头肌远端肌腱长度、肌腱到腱膜间距离、肌腱与腱膜间夹角以及该夹角顶点到肱血管、正中神经间距离.[结果] 26只肘关节肱二头肌远端肌腱均分为两束;肱二头肌远端肌腱左右两侧平均长度、肌腱到腱膜平均长度、肌腱与腱膜之间夹角以及两者夹角顶点到肘窝血管神经间距离差异无统计学意义(P＞0.05).[结论]肱二头肌远端肌腱在形态学上分为前内侧束和后外侧束;肌腱与腱膜之间有肱血管及正中神经穿过.详细了解肱二头肌远端肌腱形态学特点、解剖学数据以及与周围重要结构的毗邻关系,可为临床上肱二头肌远端肌腱损伤的诊断及治疗提供参考.     

磁共振多平面成像显示胆胰管汇合解剖特征

目的 探讨磁共振成像(MRI)显示胆胰管汇合区域精细解剖结构及其变异的可行性和价值.方法 研究纳入112例行上腹部MRI增强扫描的受检者,排除了临床及实验室检查证实有胰胆管疾病的患者.观察十二指肠乳头的位置、胆胰管汇合的方式,测量胆胰共同管或胆总管与十二指肠的夹角、胆胰管夹角.结果 大乳头位于十二指肠降部上、中、下段者分别占17.0%、66.0%、17.0%,胆胰共同管或胆总管与十二指肠的夹角为44.4°;胆胰管在十二指肠壁内汇合占11.6%,壁外汇合占80.4%,分别注入占8.0%,胆胰管夹角为37.8°.结论 MRI能清晰显示胆胰管汇合特征,能较好显示胆胰管不同汇合方式的细微差别,为临床诊断及治疗胆胰管汇合区疾病提供精细的影像解剖信息.

Abstract：

Objective To explore the use of magnetic resonance imaging (MRI) in the display of detailed anatomical structures at the pancreaticobiliary junction. Methods 112 patients who received enhanced MRI of upper abdomen were included in the study. Patients with pancreatic and/or biliary diseases diagnosed clinically and with laboratory tests were excluded. The types of junction between the terminal common bile duct and the pancreatic duct, and the location of the major duodenal papilla were studied on MRI. We measured the angle between the duodenum and the common pancreaticobiliary duct or the common bile duct. Results Of the 112 patients, the duodenal papillas were located at the upper, middle, and lower segment of the duodenum in 17. 0%, 66. 0% and 17. 0%, respectively.The angle between the common pancreaticobiliary duct or the distal common bile duct and the descending duodenum was 44. 4°±17. 3°. The pancreatic duct and the common bile duct opened separately in 9 patients (8. 0%). The confluence of the two ducts was present inside and outside of the duodenum wall in 13 (11. 6%) and 90 patients (80. 4%), respectively. The angle between the distal common bile duct and the pancreatic duct was 37. 8°±15.1°. Conclusion MRI was able to display detailed anatomical structures of the pancreaticobiliary junction, including the angle of the junction between the two ducts and the location of the duodenal papilla. It has the ability to provide meticulous anatomical data for the diagnosis and treatment of diseases at the pancreaticobiliary junction and to help surgeons formulate operative plans.     

Functional magnetic resonance imaging and control over the biceps muscle after intercostal-musculocutaneous nerve transfer

OBJECT: Recent progress in the understanding of cerebral plastic changes that occur after an intercostal nerve (ICN)-musculocutaneous nerve (MCN) transfer motivated a study with functional magnetic resonance (fMR) imaging to map reorganization in the primary motor cortex. METHODS: Eleven patients with traumatic root avulsions of the brachial plexus were studied. Nine patients underwent ICN-MCN transfer to restore biceps function and two patients were studied prior to surgery. The biceps muscle recovered well in seven patients who had undergone surgery and remained paralytic in the other two patients. Maps of neural activity within the motor cortex were generated for both arms in each patient by using fMR imaging, and the active pixels were counted. The motor task consisted of biceps muscle contraction. Patients with a paralytic biceps were asked to contract this muscle virtually. The location and intensity of motor activation of the seven surgically treated arms that required good biceps muscle function were compared with those of the four arms with a paralytic biceps and with activity obtained in the contralateral hemisphere regulating the control arms. Activity could be induced in the seven surgically treated patients whose biceps muscles had regained function and was localized within the primary motor area. In contrast, activity could not be induced in the four patients whose biceps muscles were paralytic. Neither the number of active pixels nor the mean value of their activations differed between the seven arms with good biceps function and control arms. The weighted center of gravity of the distribution of activity also did not appear to differ. CONCLUSIONS: Reactivation of the neural input activity for volitional biceps control after ICN-MCN transfer, as reflected on fMR images, is induced by successful biceps muscle reinnervation. In addition, the restored input activity does not differ from the normal activity regulating biceps contraction and, therefore, has MCN acceptor qualities. After ICN-MCN transfer, cerebral activity cannot reach the biceps muscle following the normal nervous system pathway. The presence of a common input response between corticospinal neurons of the ICN donor and the MCN acceptor seems crucial to obtain a functional result after transfer. It may even be the case that a common input response between donor and acceptor needs to be present in all types of nerve transfer to become functionally effective.     

Defining the cross-sectional anatomy important to interscalene brachial plexus block with magnetic resonance imaging

Background and Objectives. Interscalene brachial plexus block is a useful technique to provide anesthesia and analgesia for the shoulder and proximal upper extremity. The initial needle direction at the interscalene groove has been described as being “perpendicular to the skin in every plane” (1). A cross-sectional (axial) approach may offer a more easily conceptualized directed needle placement. The purpose of this study is to define the cross-sectional anatomy and idealized needle angles important to interscalene brachial plexus block. Methods. Following IRB approval, 50 patients were studied. Cross-sectional volume coil T1-weighted magnetic resonance images (MRI) were obtained from 50 patients undergoing cervical region imaging for other reasons. At the interscalene groove, a simulated needle path to contact the ventral rami or trunks of the brachial plexus was approximated at the level of C6 or C6–C7 interspace. The angle of this needle path intersecting the sagittal plane was recorded for each patient. Results. The mean angle of the simulated needle path relative to sagittal plane was determined to be 61.1 ± 6.1° (range, 50–78°). In 13 of 50 (26%) MRI scans, the cervical nerve roots were not visualized at the level of C6 and were measured at the C6–C7 level. Conclusions. These findings suggest initial needle placement at the interscalene groove should be angled less perpendicularly relative to the sagittal plane than is often observed. A cross-sectional approach enables more practical visualization of initial needle placement. A more accurate initial needle placement may minimize the number of needle passes necessary to contact the nerve roots, thereby more efficiently obtaining a successful block.     

The anatomy of the thoracic spinal canal investigated with magnetic resonance imaging (MRI)

BACKGROUND AND OBJECTIVES: Anesthesiologists are reluctant to consider higher levels for spinal anesthesia, largely due to direct threats to the spinal cord. The goal of this study is to investigate, with magnetic resonance imaging (MRI), the distances between the relevant structures of the spinal canal (spinal cord, thecal tissue, etc.) to determine modal anatomical positions for neuraxial anesthesia. METHOD: A group of 19 patients were imaged with an MRI scanner in supine position. Medial sagittal slices of the thoracic and lumbar spine were measured for the relative distances between anatomical structures, including epidural space, dura, and spinal cord. RESULTS: The posterior dura - spinal cord distance is significantly greater in the middle thoracic region than at upper and lower thoracic levels (e.g. T6 9.5 +/- 1.8 mm, T12 3.7 +/- 1.2 mm, p < 0.001, T1 4.7 +/- 1.7 mm, p < 0.001). There is variation in modal distances between the structures important for neuraxial anesthesia, at different levels of the spinal canal. CONCLUSIONS: The spinal cord tends to follow the straightest line through the imposed geometry of the spine. Considering the necessary angle of entry of the needle at mid-thoracic levels, there is relatively (more than at upper thoracic and lumbar levels) substantial separation of cord and surrounding thecal tissue. Anesthesiologists perform spinal blockades up to the L2-L3 interspace, but avoid higher levels for fear of neurological damage. The information that there is substantially more space in the dorsal subarachnoid space at thoracic level, might lead to potential applications in regional anesthesia. In contrast, the cauda equina sits more dorsally in the lumbar region.     

Oral sedation with midazolam and diphenhydramine compared with midazolam alone in children undergoing magnetic resonance imaging

BACKGROUND: The purpose of this study was to compare the safety and efficacy of oral midazolam and midazolam-diphenhydramine combination to sedate children undergoing magnetic resonance imaging (MRI). METHODS: We performed a prospective randomized double-blind study in 96 children who were randomly allocated into two groups. Group D received oral diphenhydramine (1.25 mg x kg(-1)) with midazolam (0.5 mg x kg(-1)), and Group P received oral placebo with midazolam (0.5 mg x kg(-1)) alone. Sedation scores, onset and duration of sleep were evaluated. Adverse effects, including hypoxemia, failed sedation, and the return of baseline activity, were documented. RESULTS: Diphenhydramine facilitated an earlier onset of midazolam sedation (P < 0.01), and higher sedation scores (P < 0.01). In children who received midazolam alone, 20 (41%) were inadequately sedated, compared with 9 (18%) children who received midazolam and diphenhydramine combination (P < 0.01). Time to complete recovery was not significantly different between the two groups. CONCLUSIONS: Our study indicates that the combination of oral diphenhydramine with oral midazolam resulted in safe and effective sedation for children undergoing MRI. The use of this combination might be more advantageous compared with midazolam alone, resulting in less sedation failure during MRI.     

Differential diagnosis and staging of urological tumors by magnetic resonance imaging compared with computed tomography

Magnetic resonance imaging (MRI) was performed on 49 urological tumors (11 renal cell carcinomas, 3 renal pelvic cancers, 2 renal angiomyolipomas, 1 renal leiomyosarcoma, 1 large renal cyst, 4 adrenal tumors, 11 bladder cancers, 2 bone metastasis from bladder cancer, 10 prostatic cancers, 1 prostatic sarcoma, 1 urethral cancer, 1 penile cancer and 1 perivesical granuloma) since October 1985 to September 1986. MRI was performed using a Signa (G.E.) with a 1.5T superconductive magnet and 3 images, including T1 weighted image, T2 weighted image, and proton density image, were obtained. In conclusion MRI is a noninvasive examination and gives more information than computed tomography despite its high cost. In renal cell carcinoma, the chemical shift in MRI and clear visualization of tumor thrombus enable accurate staging. Differential diagnosis from other renal mass lesions may be possible by the T2 weighted image. In adrenal disease, most of the adrenal masses can be differentiated, but in some cases it is impossible. In bladder cancer, wall invasion of tumor may be evaluated in T2 weighted image, and MRI is suitable for staging of locally advanced tumor. In prostatic cancer, visualization of periprostatic plexus and differentiation between internal and external gland may enable local staging and identification of low stage tumors.     

Staging of bladder carcinoma by magnetic resonance imaging compared with computed tomography and transurethral echography

Various techniques are used for tumor staging of bladder carcinoma such as endoscopic photography, transurethral echography, and computed tomographic (CT) scan. Endoscopic photography enables easy observation of tumor morphology, but we utilized other approaches to determine the presence or absence of tumor infiltration. Magnetic resonance imaging (MRI) has recently found widespread use in the staging of tumors. We first employed this approach at our hospital in February 1987. We compared the diagnostic accuracy rate of MRI with that of transurethral echography and CT scan in 10 cases of bladder tumor. The diagnostic accuracy rate of MRI was 70%, while that of transurethral echography and CT scan was 40% and 50%, respectively. We concluded that MRI was very useful in the diagnostic staging of bladder tumor.     

A study of the anatomy of the caudal space using magnetic resonance imaging

We have studied, in 37 adult patients, the anatomy of the sacral extradural (caudal) space using magnetic resonance imaging. The sacrococcygeal membrane (SCM) could not be detected in 10.8% of patients. The maximum depth of the caudal space adjacent to the SCM was beneath the upper third of the SCM in more than 90% of patients (mean depth 4.6 mm; range 1.0-8.0 mm). The shortest linear distance from the dura to the upper limit of the SCM varied considerably (60.5 mm; 34-80 mm) as did the volume of the caudal space excluding the foraminae and dural sac (14.4 cm3; 9.5-26.6 cm3). The dimensions of the caudal space and their variability have implications for clinical practice and a knowledge of these dimensions may increase both the reliability and safety of caudal techniques in adult patients.      

The congruence of the distal radioulnar joint. A magnetic resonance imaging study

The functional anatomy of the distal radioulnar joint was studied in 10 healthy volunteers. The joint surface of both the ulnar head and the sigmoid notch of the radius form arcs of circles with small areas of contact because the diameters of the circles are different. The distal radioulnar joint is congruent throughout its range of motion, but the area of contact shifts from dorsal in the sigmoid notch in pronation to volar in supination. The insertion of the distal radioulnar ligaments on the ulnar head explains the congruence of the joint.     

Renal magnetic resonance imaging

PURPOSE OF REVIEW: Current magnetic resonance imaging systems allow the visualization of normal and diseased kidney, with exquisite resolution of renal structures. Dynamic contrast magnetic resonance imaging has the potential, unique among all noninvasive modalities, to differentiate diseases that affect different portions of the vascular-nephron system. This article reviews the most important recently published studies in selected topics chosen because of their clinical relevance or potential for technical developments. RECENT FINDINGS: Magnetic resonance imaging is used increasingly to evaluate renal masses, the prenatal genitourinary system, urinary obstruction and infection, renal vasculature, and the kidneys of transplant donors and recipients. Dynamic contrast magnetic resonance renography based on gadolinium chelated to diethylenetriamine pentaacetic acid, a safe (non-nephrotoxic) paramagnetic agent, emerges as the functional renal imaging modality of choice. Both perfusion and filtration rates can be assessed in individual kidney. SUMMARY: Magnetic resonance imaging has the potential to provide a complete anatomic, physiologic, kidney-specific evaluation. With future advances in automated image analysis methods we can expect functional renal magnetic resonance imaging to play an influential role in management of renal disease.     

Stereotactic imaging for radiosurgery: localization accuracy of magnetic resonance imaging and positron emission tomography compared with computed tomography

Computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) provide complementary information for treatment planning in stereotactic radiosurgery. We evaluated the localization accuracy of MRI and PET compared with CT. Two kinds of phantoms applicable to the Leksell G stereotactic skull frame (Elekta, Tokyo) were developed. Deviations of measured coordinates at target points (x = 50, 100, 150; y = 50, 100, 150) were determined on different axial planes (z = 30-140 for MRI and CT study and Z = 50-120 for PET and CT study). For MRI, the deviations were no more than 0.8 mm in each direction. For PET, the deviations were no more than 2.7 mm. For both imaging modalities studied, accuracy was at or below the imaging resolution (pixel size) and should be considered useful for clinical stereotactic planning purposes.