Magnetic resonance imaging versus bone scintigraphy in suspected scaphoid fracture

Magnetic resonance imaging (MRI) has become increasingly useful in the evaluation of musculoskeletal problems, including those of the wrist. In patients with a wrist injury, MRI is used mainly to assess vascularity of scaphoid non-union. However, the use of MRI in patients in the acute phase following carpal injury is not common. Three-phase bone scintigraphy is routinely performed from at least 72 h after injury in patients with suspected scaphoid fracture and negative initial radiographs. We evaluated MRI in this patient group. The bone scan was used as the reference method. Nineteen patients were included. Bone scintigraphy was performed in all 19 patients, but MRI could be obtained in only 16 (in three patients, MRI was stopped owing to claustrophobia). In five patients, MRI confirmed a scintigraphically suspected scaphoid fracture. In one patient, a perilunar luxation, without a fracture, was seen on MRI, while bone scintigraphy showed a hot spot in the region of the lunate bone, suspected for fracture. This was confirmed by surgery. In two patients, a hot spot in the scaphoid region was suspected for scaphoid fracture, and immobilization and employed for a period of 12 weeks. MRI was negative in both cases; in one of them a scaphoid fracture was retrospectively proven on the initial X-ray series. In another two patients, a hot spot in the region of MCP I was found with a negative MRI. In both, the therapy was adjusted. In the remaining six patients, both modalities were negative. We conclude that in the diagnostic management of patients with suspected scaphoid fracture and negative initial radiographs, the use of MRI may be promising, but is not superior to three-phase bone scintigraphy.     

Significance of a hot spot on the bone scan after carpal injury —evaluation by computed tomography

The use of bone scintigraphy in patients with negative radiographs after carpal injury is widely advocated. However, focally increased activity on the bone scan in the scaphoid or other carpal bones cannot always be radiologically confirmed as a fracture. To confirm scintigraphically suspected carpal fractures, computed tomography (CT) of the wrist was performed in patients with clinically suspected scaphoid fracture and initially negative radiographs. All patients underwent plain radiography, bone scintigraphy and CT. The combination of plain radiographs and CT, as judged by a panel of experienced observers, was used as the reference standard. In 18 patients, 21 out of 22 carpal hot spots on bone scintigraphy could be radiologically confirmed as a fracture. The diagnosis was missed by CT scan in three patients with proven fractures on plain radiographs. We conclude that, in patients with negative initial radiographs following carpal injury, a positive bone scan must be interpreted as a fracture. Correspondence to: M.M.C. Tiel-van Buul     

A comparison of bone scintigraphy and MRI in the early diagnosis of the occult scaphoid waist fracture

Objective. To determine the accuracy of MRI in the assessment of the radiographically occult scaphoid fracture. Design. This prospective study compared the sensitivity and specificity of MRI for detection of radiographically occult scaphoid fractures with bone scintigraphy (BS), the currently accepted imaging modality of choice. Consecutive patients with clinical signs of a scaphoid injury but no evidence of fracture on plain radiographs at presentation and after 7–10 days were evaluated by MRI and BS. All images were reported in masked fashion and the sensitivities and specificities of the imaging modalities determined. All patients with a scaphoid fracture demonstrated by MRI or BS were followed for at least a year after injury. Patients. Forty-three subjects (aged 12–74 years) had both MRI and BS carried out on average 19 days from the injury date. Results and conclusions. Six patients (14%) had scaphoid waist fractures. There were other bony injuries in a further six. In 40 patients there was agreement between the BS and MRI findings. In three cases there was discrepancy between the imaging modalities; in all three MRI was found to be the more sensitive and specific. MRI could become the investigation of choice for this injury.     

16 detector multislice CT versus skeletal scintigraphy in the diagnosis of wrist fractures: value of quantification of 99Tcm-MDP uptake

To compare the measured uptake of 99Tcm-methylene diphosphonate (99Tcm-MDP) in those scaphoid fractures seen on both 16 detector multislice CT and scintigraphy, with those seen only on scintigraphy. Over a 12 month period a total of 51 patients with suspected fracture underwent both conventional 99Tcm-MDP scintigraphy and 16 detector multislice CT on the same day. The 99Tcm-MDP uptake was then quantified in patients with identified fracture. This was measured by placing a region of interest (ROI) over the fracture site and the mean and maximum number of counts were compared with those in a similar size ROI placed over background bone activity. A total of 23 fractures were identified on scintigraphy of which 16 were also detected on CT (concordant). In seven cases the fracture was not seen on CT, even in retrospect (discordant). In the discordant cases, follow-up radiographs and MRI (where available) also failed to demonstrate a fracture. The mean fracture count to background bone activity ratio averaged 7.7 (range 3.2-18.5) for concordant fractures and 3.8 (range 1.7-5.3) for discordant fractures (t-test p=0.04). The maximum fracture count to background bone activity ratio averaged 12.7 (range 4.3-27.7) for concordant fractures and 6.3 (range 2.6-9.5) for discordant fractures (t-test p=0.03). It is speculated whether these discordant fractures with less 99Tcm-MDP uptake may represent a less severe injury such as bone bruise.     

Value of bone scintigraphy in patients with carpal trauma

OBJECTIVE: We planned this study to evaluate the role of bone scintigraphy in patients with suspected carpal fracture and normal or suspicious radiographs following carpal injury. METHODS: Three-phase bone scintigraphy using Tc-99m-MDP was performed on 32 patients with negative radiographs but clinically suspected fracture at two weeks after the trauma. Focally increased radiopharmaceutical uptake was interpreted as a fracture. The final diagnosis was established with clinical follow-up. RESULTS: Twelve (38%) patients had a normal scan excluding fracture. Twelve patients had a single fracture. Multifocal fracture was present in 8 (25%) patients. Eight patients showed scaphoid fractures; of these three showed single scaphoid fracture, and the other five patients revealed accompanying fractures. Distal radius fractures and carpal bone fractures other than scaphoid were both observed in 12 patients. These were eleven fractures of distal radius; three fractures of pisiform; two fractures of hamate; and single fractures of lunate, trapezium and triquetrum. In one patient there was fracture of a first metacarpal bone. CONCLUSION: In patients with suspected carpal bone fracture and normal or suspicious radiographs, bone scintigraphy can be used as a reliable method to confirm or exclude the presence of a scaphoid fracture and to detect clinically unsuspected fractures of distal radius and other carpal bones.     

反射性交感神经营养不良的影像学诊断

目的探讨反射性交感神经营养不良(RSD)影像学诊断的意义。方法收集并分析5例反射性交感神经营养不良的临床和影像学特点。结果全部患者均在外伤后起病,均有错位疼痛、局部水肿和感觉过敏等临床表现。X线平片和CT检查均可发现病变部位的斑片状骨质疏松,CT检查优于平片。4例患者行骨扫描检查发现病变部位均有放射性异常浓集影。1例早期患者行MR I检查,能发现在平片中不易发现的骨侵蚀。结论平片和CT扫描显示的斑片状骨质疏松是本病最具特征性的影像学表现,骨扫描和MR I有助于本病的早期诊断。     

Scaphoid and pronator fat stripes are unreliable soft tissue signs in the detection of radiographically occult fractures

AIM: To determine the clinical value of scaphoid and pronator fat stripes in identifying occult underlying scaphoid and distal radius fractures, respectively. MATERIALS AND METHODS: In our department, all patients with clinically suspected scaphoid fractures and normal scaphoid series of radiographs undergo magnetic resonance imaging (MRI) of the wrist. We selected 50 cases with unequivocal MRI evidence of scaphoid fracture, 50 cases with distal radius fracture and 50 cases with no MRI evidence of bony injury. All 150 initial plain radiographs were examined retrospectively in random order without knowledge of the MRI findings and the scaphoid and pronator fat stripes scrutinized. RESULTS: The scaphoid fat stripe was abnormal in only 25 cases (50%) with confirmed scaphoid fracture on MRI. The pronator fat stripe was abnormal in 13 cases (26%) with confirmed distal radius fracture. In the 50 cases with no MRI evidence of bony injury, the scaphoid fat stripe and pronator fat stripe were abnormal in 25 (50%) and 15 (30%) cases, respectively. The sensitivity and specificity for an abnormal scaphoid fat stripe was 50%. The sensitivity and specificity for an abnormal pronator fat stripe was 26 and 70%, respectively. CONCLUSION: Scaphoid and pronator fat stripes are poor predictors of the presence or absence of underlying occult fractures.     

An approach to medical imaging for sports-related injuries

Medical imaging plays a valuable role in the evaluation and management of sports-related injuries. Although most acute injuries can be evaluated satisfactorily by clinical assessment and standard radiographs, some types of injuries require additional imaging for localization and characterization. The more advanced technologies (bone scintigraphy, computed tomography [CT], and magnetic resonance imaging [MRI]) provide sensitive physiological or detailed anatomic information in evaluating the athletes complaints. Stress injuries are common sports-related injuries, and they are detected most frequently by bone scintigraphy. Pars interarticularis injuries of the spine are best identified by bone scintigraphy. Other anatomic regions of stress injury include upper extremity complaints from throwing sports and lower extremity symptoms from running and jumping activities.When the management of symptoms is uncertain based on clinical assessment and plain radiographs and the area of involvement is not well defined, bone scintigraphy is extremely sensitive to injuries causing increased bone turnover. To show detailed anatomy, the cross-sectional modalities (CT and MRI) are without equal. CT allows exquisite bone detail when subtle injuries, particularly in areas of complex anatomy, are suspected at a specific site. MRI is the procedure of choice when bone marrow and soft-tissue injuries are of concern in a specific anatomic region.     

Scintigraphic pattern in a case of Tarlov cyst

We report the case of a 40-year-old man remitted to our department with a history of lower back pain and sciatica with no history of trauma. The laboratory analyses showed normal values whereas plain radiographs showed a sacrum rarefaction area. A 99mTc-MDP bone scintigraphy was performed to evaluate the lumbosacral area. Planar images did not show any abnormality. SPECT images revealed photopenic abnormality in the second sacral vertebral right hemibody, with no peripherally increased radiotracer accumulation. Subsequent MRI and CT myelography demonstrated the nature of the photopenic area as secondary to vertebral erosion by sacral perineurial cyst (Tarlov cyst).     

Imaging features of spinal osteoid osteoma with emphasis on MRI findings

A retrospective evaluation of the imaging of 13 patients with a diagnosis of osteoid osteoma (OO) of the spine was undertaken. Available imaging included radiographs (n=10), computed tomography (CT) (n=13), bone scintigraphy (n=5) and magnetic resonance imaging (MRI) (n=13). MRI features evaluated were pattern of neural arch and vertebral body oedema and the presence of an identifiable nidus. MRI features were correlated with other available imaging. There were seven males and six females with an age range of 8–59 years. On radiographs, scoliosis was present in ten and a sclerotic pedicle in nine patients. Focal increased uptake on bone scintigraphy consistent with OO was seen in all five patients where scintigraphy was available. On CT, a nidus was identified in all patients and reactive sclerosis was seen in 12. MRI demonstrated the nidus in eight patients and unilateral neural arch oedema with anterior extension to involve the ipsilateral posterolateral vertebral body in 11. When MRI is performed in the evaluation of back pain, the presence of unilateral neural arch oedema extending to involve the posterolateral vertebral body raises the possibility of spinal OO and should prompt CT to confirm the presence of a nidus.     

PET/CT of a brodie abscess

Brodie abscess is a rare, localized type of subacute or chronic pyogenic osteomyelitis, usually of staphylococcal origin. Imaging with standard radiographs, bone scintigraphy, and MRI has been described in the literature. We present the case of a 28-year-old patient with pain in the right knee. Whole-body FDG-PET/CT scan showed a solitary FDG-active (SUV max 5.2) intracortical lesion in the meta-/epiphysis of the proximal tibia. CT demonstrated a sclerotic rim around the lesion. A Brodie abscess was considered a possible diagnosis. Multifocality could be excluded. CT-guided transosseous biopsy and curettage was performed and the diagnosis of a Brodie abscess was confirmed.     

Reliability of bone scintigraphy for suspected scaphoid fractures

PURPOSE: To examine the observer variation for bone scintigraphy in the detection of occult scaphoid fractures in daily practice, using only the early bone scanning images. METHODS: One hundred bone scans of patients with a suspected scaphoid fracture but negative initial radiographs were prospectively included to calculate the inter- and intraobserver variation. Three nuclear medicine physicians independently evaluated all bone scans at 2 different points in time with a 3-month interval. The observers filled out a blinded scoring sheet for each patient. They scored if a scaphoid fracture was present or not. In addition, they scored the presence or absence of another fracture. The inter- and intraobserver variation was analyzed using the kappa statistic. RESULTS: The interobserver variation showed substantial agreement for a scaphoid fracture and almost perfect agreement for another fracture. The intraobserver variation showed almost perfect agreement for both a scaphoid fracture and another fracture. CONCLUSIONS: In the present study, early static images of bone scintigraphy for suspected scaphoid fractures showed very little inter- and intraobserver variation. In addition, expertise does not seem to have a negative influence on the results. This enhances the possibility of using bone scintigraphy in daily practice.     

The management of scaphold fractures.

Appropriate management of scaphoid fractures is important because of the risk of long-term complications such as delayed or non-union, pain and disability. Up to 25% of scaphoid fractures are not visible on the initial radiographs. Consequently, all clinically suspected scaphoid fractures are treated as fractures with cast immobilisation until cause of the symptoms is clarified. The diagnosis often utilises a number of second line investigations that are generally performed 10-14 days after the injury. Bone scintigraphy is currently the most commonly used of these as it rarely misses a fracture. However, it does not visualise anatomical structure and therefore alternative diagnoses are difficult. Magnetic resonance imaging (MRI) is at least as sensitive and more specific than bone scanning and has the advantages of being able to identify other lesions and not expose the patient to any radiation. Furthermore, the scan may be performed as early as 2.8 days following an injury rather than 10 days later in the case of a bone scan. Although the cost of MRI is higher than other imaging modalities, it may be cost-effective in the overall management of patients with occult scaphoid fractures since it may prevent unnecessary cast immobilisation in active people. The most appropriate method of cast immobilisation is presently unclear but evidence exists for improved clinical outcomes in those that have both the thumb and elbow immobilised for the first six weeks.     

Magnetic resonance imaging of suspected scaphoid fractures using a low field dedicated extremity MR system

AIM: To determine whether magnetic resonance imaging (MRI) using a dedicated extremity system could be utilized for the routine assessment of patients with a clinically suspected scaphoid fracture, and to determine the most cost-effective timing of MRI for these patients. MATERIALS AND METHODS: MRI of the wrist using a 0.2T extremity MR system was performed in two groups of patients. Fifty-six patients were examined within 4 days of injury and 53 with persistent symptoms at 10 days to 6 weeks following injury. A scaphoid series of radiographs was negative in both groups. RESULTS: The early MR group had seven scaphoid, six radial and four other fractures. Management was altered in 89%. The late MR group had 14 scaphoid, nine radial and three other fractures. Management was altered in 69%. A cost model showed that overall costs are less with early rather than late scanning. CONCLUSION: MRI of the wrist when scaphoid fracture is suspected can be undertaken in all patients with negative radiographs and could be performed in most departments with an MRI machine. There are significant patient benefits and overall costs would change little from conventional practice.     

Wrist injuries in young adults: The diagnostic impact of CT and MRI

Purpose

To evaluate the diagnostic impact of MRI or/and multidetector CT in young patients with wrist injury and inconclusive or negative clinical examination and X-rays and to analyze variations in imaging strategies between a district general hospital (GH) and a university hospital (UH).

Materials and methods

A retrospective analysis of 34 young patients (mean age 23 years) with wrist trauma who underwent CT or/and MRI was performed. The injury was acute in 24, and chronic in 10 patients. Twenty-two patients were from a GH and 12 from a UH. Two experienced musculoskeletal radiologists blindly reviewed the imaging studies. The effect of cross-sectional imaging on patient care and treatment plan was evaluated.

Results

In 9 of 34 patients one or more fractures were diagnosed on cross-sectional imaging. The scaphoid was fractured in four patients, the lunate and/or the trapezium in three patients, the scaphoid together with the lunate in one patient, and finally the distal radius in one patient. Ligamentous trauma was identified solely on MRI in 11 patients (involving the TFCC in eight cases). In four patients with both imaging methods, CT revealed one fracture of the trapezium not seen on MRI, and one scapholunate fracture with MRI findings of distal radial fracture only. In two patients with normal CT, MRI revealed bone marrow oedema of the scaphoid in one and of the distal radius, lunate and triquetrum in the other.

Conclusion

Both CT and MRI might be considered in patients with acute or chronic wrist injury, clinical dilemma and normal initial radiographs, depending on the availability and the individual institution policies.     

CT of the wrist in suspected scaphoid fracture.

Bone scan and sagittal projection CT of the scaphoid was performed in 10 patients with clinically suspected scaphoid fractures. The primary and follow-up plain radiographs were negative or equivocal for fracture. CT examination demonstrated scaphoid fracture in 7 patients and normal findings in 3. It is concluded that CT of the scaphoid can replace bone scan to diagnose or rule out fracture in institutions where nuclear medicine facilities are not available.     

MRI as a reference standard for suspected scaphoid fractures

Objectives

Some have suggested that MRI might be the best reference standard for a true fracture among patients with suspected scaphoid fractures. The primary aim of this study was to determine the rate of false-positive diagnosis of an acute scaphoid fracture in a cohort of healthy volunteers.

Methods

In a prospective study, 33 healthy volunteers were recruited and both wrists of each were scanned, except for 2 volunteers for whom only one wrist was scanned. To simulate the usual clinical context the 64 scans of healthy volunteers were mixed with 60 MRI scans of clinically suspected scaphoid fractures but normal scaphoid radiographs. These 124 MRI scans were blinded and randomly ordered. Five radiologists evaluated the MRI scans independently for the presence or absence of a scaphoid fracture and other injuries according to a standard protocol.

Results

To answer the primary question, only the diagnoses from the 64 scans of healthy volunteers were used. The radiologists diagnosed a total of 13 scaphoid fractures; therefore, specificity for diagnosis of scaphoid fracture was 96% (95% confidence interval: range 94–98%). The 5 observers had a moderate interobserver agreement regarding diagnosis of scaphoid fracture in healthy volunteers (multirater κ=0.44; p<0.001).

Conclusions

The specificity of MRI for scaphoid fractures is high (96%), but false-positives do occur. Radiologists have only moderate agreement when interpreting MRI scans from healthy volunteers. MRI is not an adequate reference standard for true fractures among patients with suspected scaphoid fractures.The American College of Radiologists recommends MRI for diagnosis of true fractures among suspected scaphoid fractures [1]. A number of published studies cite sensitivities and specificities approaching 99% [2-9], but other studies have reported a lower sensitivity (80%) and substantial interobserver variation (κ=0.67) for diagnosis of a scaphoid fracture [2,8]. It has been difficult to agree upon a reliable reference standard for true fractures among suspected scaphoid fractures, and these studies often use only repeated radiographs 6 weeks after trauma as reference standard. However, it is also known that not all occult scaphoid fractures become apparent on repeated radiographs.It is not clear how to distinguish true fracture from other changes in bone signal that are detected with MRI. We propose that MRI of the wrists of healthy volunteers with no history of wrist or hand injury represents a reliable reference standard for the absence of an acute fracture of the scaphoid waist. By evaluating MRI scans of healthy volunteers, we may learn more about the diagnostic performance characteristics of MRI for suspected scaphoid fracture. A set of MRI scans with a reliable reference standard would also provide useful information about the reproducibility of the interpretation of MRI for suspected scaphoid fracture.The primary study question was to investigate the occurrence of false-positive diagnosis of an acute scaphoid fracture on MRI using a reliable reference standard (healthy volunteers). Secondarily we also investigated the interobserver variation of diagnosis of scaphoid fracture on MRI in healthy volunteers.     

Scaphoid fracture and nonunion: current status of radiological diagnostics

Scaphoid fractures, which involve approximately two-thirds of all wrist injuries, are often not detected during initial radiographic examination. By using high-resolution CT and dedicated MRI, it is possible to recognize scaphoid fractures soon at the first diagnostic approach and to assess fragment stability. CT imaging provides all the relevant information of the fracture extent and of the fracture healing in the follow-up. MRI is most sensitive in the detection of scaphoid fractures; however, fracture signs must be differentiated from those of a bone bruise. Both the initially overseen scaphoid fracture and the unsuccessful healing can lead to the natural history of scaphoid nonunion. In the injured scaphoid, CT imaging is essential for depicting the osseous morphology, whereas contrast-enhanced MRI is crucial for assessing the viability of the proximal fragment.     

16-Detector multislice CT-skeletal scintigraphy image co-registration

OBJECTIVE: Co-registration of bone scintigrams with radiographs has been used in the diagnosis of wrist injuries, although co-registration of tomographic bone scintigraphy with computed tomography (CT) has not been widely reported. We describe a co-registration technique in patients with possible wrist fracture. METHODS: The technique was used on three patients and involved placing the wrist on a Perspex board and tracing the outline of the forearm and hand with a pen to try and ensure accurate repositioning on the board for the two sets of imaging. Four point source markers were attached to the board during both examinations. Single photon emission computed tomography (SPECT) was performed 4 h after injection Tc-methylenediphosphonate (MDP), using a dual-headed gamma camera. CT images were acquired on a 16-detector CT unit. The SPECT and CT images were co-registered with commercially available image fusion software. The centre of the four markers was identified in both sets of images and a rigid body point match algorithm was used. Before patient studies, the technique was tested using a phantom. RESULTS: In all the phantom and clinical studies it was possible to identify the positions of all the markers. There were varying degrees of success in patient repositioning. CONCLUSION: We describe a technique that may aid the fusion of functional images from skeletal scintigraphy with the exquisite anatomical detail from the latest CT technology, in the detection of occult wrist fractures. The technique may aid fracture localization and/or detection and might help distinguish the clinically important scaphoid fractures from other benign carpal lesions.     

Skaphoidfraktur und -pseudarthrose

Scaphoid fractures, which involve approximately two-thirds of all wrist injuries, are often not detected during initial radiographic examination. By using high-resolution CT and dedicated MRI, it is possible to recognize scaphoid fractures soon at the first diagnostic approach and to assess fragment stability. CT imaging provides all the relevant information of the fracture extent and of the fracture healing in the follow-up. MRI is most sensitive in the detection of scaphoid fractures; however, fracture signs must be differentiated from those of a bone bruise. Both the initially overseen scaphoid fracture and the unsuccessful healing can lead to the natural history of scaphoid nonunion. In the injured scaphoid, CT imaging is essential for depicting the osseous morphology, whereas contrast-enhanced MRI is crucial for assessing the viability of the proximal fragment.