The diabetic foot: Charcot joint and osteomyelitis

Foot problems are common causes of disability in diabetic patients with as many as 25% expected to develop severe foot or leg problems during their lifetimes. Although skin ulceration is the most frequent problem, bones may also be involved in two different clinical conditions: osteomyelitis and Charcot osteoarthropathy. Osteomyelitis causes complications in up to one third of diabetic foot infections and is due to direct contamination from a soft-tissue ulcer. Osteoarthropathy Charcot foot is a chronic and progressive disease of the bone and joints. Both osteomyelitis and Charcot joint are conditions with an increased risk of lower limb amputation, both may have a successful outcome when recognized and treated in the early stages. The major diagnostic difficulty is in distinguishing bone infection (osteomyelitis) from non-infectious neuropathic bony disorders as in osteoarthropathy Charcot foot. An additional difficulty is found when a bone infection superimposes a Charcot osteopathy. This condition, which can be clinically suspected when foot ulceration appears in Charcot foot, needs to be diagnosed because it implies a different therapeutic strategy. This article aims to summarize both these two clinical conditions and give indications to make a timely and correct diagnosis.     

Differentiation of bone and bone marrow infarcts from osteomyelitis in sickle cell disorders

To determine whether imaging techniques can differentiate osteomyelitis from bone infarction in sickle cell disorders, 39 sets of bone scans (BS) and bone marrow scans (BMS) were performed on 31 patients with sickling disorders and bone pain. In addition, three patients who had either a BS or a BMS were included. Results were analyzed according to whether scans were performed three days or less (Period 1), four to six days (Period 2), or seven or more days (Period 3) after the onset of pain. Regardless of the period, all but five BMS for 34 episodes of assumed infarction showed decreased uptake. BS findings varied depending on the time interval, with none of the ten in Period 1 showing increased uptake, but all 11 in Period 3 showing increased uptake. However, in Period 2, about half of the 13 BS showed increased uptake. All three patients with osteomyelitis in Period 3 had increased uptake on BS. The BMS done in one of these patients showed decreased uptake. Three patients with cellulitis had normal BS and BMS. One patient with septic arthritis had normal BMS, but slightly increased uptake on BS. Although typical imaging patterns are present in early and late infarction (Periods 1 and 3), the patterns for late infarction may not differ from those of advanced osteomyelitis. Therefore, imaging studies are only of value in differentiating infarction from osteomyelitis when both BS and BMS are performed soon after the appearance of symptoms.     

Combined bone marrow and gallium imaging. Differentiation of osteomyelitis and infarction in sickle hemoglobinopathy

The clinical records and scintigrams of patients with sickle hemoglobinopathy who underwent combined Tc-99m bone marrow imaging and Ga-67 imaging to differentiate osteomyelitis from bony infarction were reviewed. Of 18 paired examinations in 15 patients, osteomyelitis was diagnosed correctly in six cases; in all six, gallium uptake at the symptomatic site was incongruently increased relative to the bone marrow activity. Of the 12 episodes of infarction, 11 showed congruent activity on both Tc-99m and Ga-67 images. The remaining study was interpreted incorrectly as osteomyelitis due to incongruent Tc-99m and Ga-67 uptake. The use of sequential Tc-99m bone marrow and Ga-67 imaging is an effective means of distinguishing osteomyelitis from bony infarction in patients with sickle hemoglobinopathy.     

Charcot关节的影像表现

目的 探讨Charcot关节的MRI表现，评价X线片、CT及MRI对Charcot关节的诊断价值。方法 对8例Charcot关节作X线、CT及MR检查，其中6例患有脊髓空洞症，1例为胸髓损伤截瘫患者，1例为糖尿病患者，所有8例均有患肢的痛觉减退或消失。结果 (1)Charcot关节表现为增生和吸收2型。(2)X线及CT特点：3例增生型关节骨质增生硬化、骨赘形成，关节周围软组织肿胀，内见大量块状骨化影；5例吸收型关节以骨质破坏吸收、碎裂为主，骨端消失，其中3例残端平齐如手术切除，周围软组织肿胀，内见多个小而锐利的骨化影。8例中有3例伴有关节半脱位。(3)主要MRI特点：8例均清楚显示关节周围软组织块影结构，7例分为3层：由内向外为关节囊内积液、关节囊壁及囊壁外其余软组织块影，1例关节囊壁与其外软组织块影分界不清，表现为2层结构。关节囊壁不均匀增厚、松弛及拉长，在关节周围、骨干旁或肌间隙内呈伪足状伸延，T1WI呈稍低信号，T2WI呈稍高信号，注射钆喷替酸葡甲胺(Gd—DTPA)后明显强化，其强化程度常高于外周的软组织块影。关节周围软组织块影的3层结构及关节囊的改变较具特点。结论 X线片是Charcot关节的首选诊断手段，MRI在Charcot关节的诊断及鉴别诊断方面是X线片重要的补充手段。     

Differentiation of hepatic hemangiomas from metastases by dynamic contrast-enhanced MR imaging

Twenty-nine patients with hepatic hemangiomas (n = 14) and hepatic metastases (n = 15) underwent magnetic resonance (MR) imaging prior to and after an intravenous bolus injection of Gd-diethylenetriamine pentaacetic acid (0.2 mmol/kg). Before contrast application, a T2-weighted spin echo sequence (SE 1,600/105) and a T1-weighted gradient echo sequence (GE 315/14/90 degrees pulse angle) were performed. Beginning with injection of the contrast agent, a dynamic study was conducted for 10 min using a moderately T1-weighted gradient echo sequence (GE 40/14/40 degrees) with an acquisition time of 10.2 s per image. Delayed (11 min) and late (60 min) postcontrast images were obtained using a T1-weighted sequence (GE 315/14/90 degrees). In the dynamic study (0-10 min) the hemangiomas were characterized by peripheral contrast enhancement and a subsequent hyperintense fill-in. The metastases showed very mixed patterns of enhancement after contrast administration, and their signal intensity remained low compared with that of the hepatic tissue. In the delayed postcontrast examination (11 min) the hemangiomas had a very high and homogeneous signal intensity and the metastases were characterized by an inhomogeneous, hypointense to isointense signal. The contrast between tumor and liver [signal-difference-to-noise ratio (SD/N)] was higher for all hemangiomas than it was for the metastases. In the T2-weighted precontrast examination, on the other hand, five hemangiomas and seven metastases showed an overlap in the SD/N. The late postcontrast images (60 min) did not yield any further diagnostic information. We conclude that the combination of a dynamic MR study with delayed postcontrast T1-weighted imaging is a useful method of diagnosing hepatic hemangiomas.     

Klebsiella pneumoniae osteomyelitis: demonstration by three-phase radionuclide bone imaging

The Klebsiella pneumoniae bacillus is a rare cause of acute hematogenous osteomyelitis of long bones. Bony involvement usually develops from a bacteremia associated with a Klebsiella pulmonary or urinary tract infection. Diabetes mellitus, alcoholism, or cirrhosis are predisposing conditions to the development of this form of osteomyelitis. A case report follows in which two sites of Klebsiella osteomyelitis were demonstrated by three-phase bone imaging in a patient with both diabetes and alcoholism.     

Hematogenous pyogenic vertebral osteomyelitis: diagnostic value of radionuclide bone imaging

Hematogenous pyogenic vertebral osteomyelitis (HPVO) continues to be a diagnostic problem for clinicians due to nonspecific presentation of the disease (1,2). We reviewed our experience of the last 10 years to determine the diagnostic usefulness of radionuclide bone studies in this disease. We found 15 patients whose primary diagnosis was HPVO. Of the 15 patients, 12 had [99mTc]MDP bone scans which were all positive. Five of the 12 patients had positive [67Ga]citrate scans and one patient with chronic active HPVO had negative 67Ga and [111In]WBC bone images. At the same time, three patients' spine x-rays and one patient's CT scan of the vertebra were normal. Additionally, in three patients spine x-rays were interpreted as consistent with degenerative joint disease that contributed to the delay of the diagnosis. We conclude that when HPVO is suspected an abnormal [99mTc]MDP bone image increases the probability of the disease, even if the x-rays and CT scans of the spine are normal. An abnormal 67Ga image following an abnormal 99mTc bone image increases the specificity of the diagnosis. Normal [99mTc]MDP and [67Ga]citrate bone images of the vertebra virtually exclude the diagnosis of HPVO.     

Differentiation of prostate cancer from benign prostate hypertrophy using dual-echo dynamic contrast MR imaging

OBJECTIVE: To investigate the usefulness of dynamic contrast magnetic resonance (MR) imaging in the differentiation of prostate cancer (PC) from benign prostate hypertrophy (BPH). MATERIALS AND METHODS: Eleven PC patients and 13 BPH patients were entered into the analysis. The mean gradient (MG) was calculated from the T2* term-eliminated time-signal intensity curve obtained from dynamic contrast MR data, and the MG of PC and that of BPH were compared. RESULTS: The MG of PC was significantly higher than that of BPH. When the threshold value was set to 1.88% per s for discriminating PC from BPH, the sensitivity, specificity, and accuracy were 100, 85, and 92%, respectively. CONCLUSION: The MG, which is derived from the T2* term-eliminated time-signal intensity curve, may be a useful index for differentiating PC from BPH.     

Malunion of a femoral fracture mimicking osteomyelitis in three phase bone imaging

A case of greatly increased blood flow in the region of a fracture with malunion of the left femur, both in the flow and immediate blood pool studies during three phase bone imaging, is presented. The sluggish left femoral artery flow resulted from the greatly increased regional perfusion and is similar to the findings in acute osteomyelitis. The sluggish left femoral artery flow and greatly increased regional perfusion of the site is probably best explained as a regional "neurovascular flush" resulting from the pain caused by the malunion of the fracture and/or hyperemia in the area of the malunion responding to inflammation.     

Multimodality imaging of osteomyelitis

Early diagnosis of osteomyelitis continues to be a clinical problem. Multiple imaging modalities are being used for the diagnosis of osteomyelitis, but none of them is ideal for all cases. The choice of modality depends on several factors based on an understanding of the pathophysiologic aspects of different forms of osteomyelitis. After a brief introduction outlining some basic principles regarding the diagnosis of osteomyelitis, pathophysiologic aspects are reviewed. Advantages and disadvantages of each imaging modality and their applications in different forms of osteomyelitis are discussed. The use of different imaging modalities in the diagnosis of special forms of osteomyelitis, including chronic, diabetic foot, and vertebral osteomyelitis, and osteomyelitis associated with orthopedic appliances and sickle cell disease is reviewed. Taking into account the site of suspected osteomyelitis and the presence or absence of underlying pathologic changes and their nature, an algorithm summarizing the use of various imaging modalities in the diagnosis of osteomyelitis is presented.     

Differentiation of normal and neoplastic bone tissue in dynamic gadolinium-enhanced magnetic resonance imaging: validation of a semiautomated technique

Purpose

This study was undertaken to clinically validate the accuracy of a semiautomated software tool for analysing the enhancement curve in focal malignant bone lesions.

Materials and methods

Twenty-three patients affected by cancer with malignant focal bone lesions underwent dynamic gadolinium-enhanced magnetic resonance (MR) imaging using the following protocol: T1-weighted turbo spin-echo sequences (time to repeat [TR] 600 ms, time to echo [TE] 8.6 ms, field of view [FOV] 40×40 cm) before and after intravenous injection of gadolinium-containing contrast agent. Image postprocessing was performed using the software DyCoH. Each region of interest (5×5 pixels), drawn to include the area of the lesion with the highest values of the area under the curve map, was analysed to obtain time-intensity curves and relative perfusion parameters: time to peak (TTP), peak intensity (PI), slope (60-s slope), intensity at 60 s after contrast agent injection (60-s I) and final intensity (FI).

Results

Data were obtained by analysing 86 malignant lesions and 86 apparently normal bone regions. PI, 60-s slope, 60-s I and FI were significantly different between neoplastic and apparently normal (p<0.001) samples. Sensitivity, specificity and accuracy were, respectively, 94%, 93% and 94% at a PI threshold of 100 (signal-to-noise ratio), with positive and negative predictive values of 93% and 94%. At a threshold value of 0.85 for 60-s slope, sensitivity and specificity values were both 91%.

Conclusions

The semiautomated technique we report appears to be accurate for identifying neoplastic tissue and for mapping perfusion parameters, with the added value of a consistent measurement of perfusion parameters on colour-coded maps.     

Interobserver variability of dynamic MR imaging of the temporomandibular joint

Purpose

This study investigated the interobserver variability of dynamic magnetic resonance (MR) imaging of the temporomandibular joint (TMJ).

Materials and methods

Sixty-two patients with internal derangement of the TMJ (124 TMJs) were investigated with a 1.5-T MR imaging system during physiological opening and closing of the mouth. Two readers evaluated independently the quality of the dynamic examination (Q: nondiagnostic, diagnostic, optimal), condylar motion (CM: limited, suboptimal, optimal), condylar orientation (CO: in-plane, through-plane shift), disc visibility and movement (DV: visible, nonvisible; DM: normal, reducing, nonreducing dislocation) and joint effusion (JE: present, absent). For each TMJ, the condylar path was measured by tracing the position of the condyle in the frames of the dynamic acquisition. Agreement between the two readers was assessed with Cohen??s Kappa and the Bland-Altman method.

Results

Interobserver agreement was almost perfect for Q (nondiagnostic, diagnostic, optimal: 0.8%, 4.9%, 94.3%; ??=1), CM (limited, suboptimal, optimal: 14%, 26.4%, 59.5%; ??=0.84) and DV (visible, nonvisible: 100%, 0%). Substantial agreement was found for DM (normal, reducing, nonreducing: 66.1%, 14.8%, 19.1%; ??=0.64) and JE (present, absent: 41.3%, 58.7%; ??=0.67). Moderate agreement was found for CO (in-plane, through-plane shift: 94.2%, 5.8%; ??=0.41). As for the condylar path, the means of the percentage differences and limits of agreement (LA) were ?3% (LA: ?34.5%, 28.3%) on the right and ?1.2% (LA: ?35%, 32.6%) on the left.

Conclusions

In dynamic imaging of the TMJ, qualitative assessment of condyle-disc movement and joint effusion is minimally dependent on the reader??s evaluation. Measurement of the condylar pathway shows an interobserver variability of ±30%.     

Combined leukocyte and bone imaging used to evaluate diabetic osteoarthropathy and osteomyelitis

Six diabetic patients with roentgenographic finding of osteomyelitis, osteoarthropathy, or both, had combined leukocyte and bone imaging. Bone images demonstrated increased activity in all cases, including three without osteomyelitis. Leukocyte images, however, showed increased activity in only the three cases of osteomyelitis. There was minimal or no activity in the other three cases where osteoarthropathy was ultimately believed to be the basis of the roentgenographic and bone imaging changes.     

Diagnosis of osteomyelitis in children by combined blood pool and bone imaging.

Differentiation of osteomyelitis from cellulitis or septic arthritis can be difficult. The radiological examination often does not have the characteristic features. Seventy of 71 children with osteomyelitis had focal areas of increased radioactivity at the site of the infection. The addition of "blood pool" images aids in the interpretation of the study as they permit evaluation of the effect of hyperemia. The 13 childrenwith cellulitis had diffuse increase in radioactivity involving both the bones and soft tissues. Bone imaging as the initial screening procedure for osteomyelitis is recommended.     

动态增强磁共振成像对肌肉骨骼系统肿瘤性质鉴别的定量研究

目的 评价动态增强ＭＲＩ鉴别良恶性肌肉骨骼（简称肌骨）肿瘤的价值。方法 前瞻性量化分析３２例肌骨肿瘤患者的动态增强磁共振图像,采用差别分析法确定良恶性患者的动态增强ＭＲＩ检查指标有无差别,并通过绘制接受者操作特征（ＲＯＣ）曲线得出最佳评价指标。采用相关分析法确定定量指标与肿瘤组织血管化程度及ＤＮＡ指数（ＤＩ）的关系。     

Differentiation of recurrent rectal cancer and scarring with dynamic MR imaging

The accuracy of dynamic contrast enhanced magnetic resonance (MR) imaging in the differentiation of malignant and benign pelvic lesions during follow-up of patients with treated colorectal tumours was evaluated prospectively. 19 patients (11 men, 8 women; age range 35-70 years; mean 57 years) with suspected local recurrence of colorectal malignancy were evaluated with MR imaging. Dynamic MR imaging with axial Turbo-FLASH gradient echo imaging and bolus injection of contrast medium was performed. Dynamic images, each consisting of one slice in the same location, were acquired at 5, 10, 15, 20 and 30 s, and at 1, 2, 3, 4, 5 and 10 min. The maximum change in signal intensity (Emax), the acceleration rate of the time-intensity curve (TIC) and the ratio of the signal intensity of the lesions to the signal intensity of the iliac artery (SIL/SIA) were used as the enhancement parameters. The TIC and SIL/SIA ratio at 60 s were found to be valuable in the differential diagnosis; Emax had no significance in differentiating benign and malignant lesions. Sensitivity was 83% for each calculated parameter. SIL/SIA has the highest specificity and accuracy among the parameters.     

Usefulness of radionuclide bone and joint imaging in vibration disease

Bone and joint imaging with ^99mTc-MDP was carried out in 17 patients with vibration disease. A comparison was made between bone scintigraphy and radiography in the regions frequently involved: cervical spine, elbow joint, wrist joint, and bone of hand. These results suggested that radiography was superior to scintigraphy in the detection of osseous changes of cervical spine, while scintigraphy was superior to radiography in the case of wrist joint and bone of hand. ^99mTc-MDP joint imaging was found to be more sensitive in the detection of involvement in peripheral joints (especially metacarpal, proximal, and distal interphalangeal joints) than radiography, but it is nonspecific. Therefore, regions of increased uptake should be radiographed to determine whether other causative factors exist.     

Usefulness of radionuclide bone and joint imaging in vibration disease

Bone and joint imaging with 99mTc-MDP was carried out in 17 patients with vibration disease. A comparison was made between bone scintigraphy and radiography in the regions frequently involved: cervical spine, elbow joint, wrist joint, and bone of hand. These results suggested that radiography was superior to scintigraphy in the detection of osseous changes of cervical spine, while scintigraphy was superior to radiography in the case of wrist joint and bone of hand. 99mTc-MDP joint imaging was found to be more sensitive in the detection of involvement in peripheral joints (especially metacarpal, proximal, and distal interphalangeal joints) than radiography, but it is nonspecific. Therefore, regions of increased uptake should be radiographed to determine whether other causative factors exist.     

骨髓炎与恶性骨肿瘤软组织改变的影像比较

目的 探讨软组织影像改变对骨髓炎和恶性骨肿瘤的鉴别诊断价值。方法 通过回顾性分析。对57例骨髓炎和70例恶性骨肿瘤患者软组织异常CT和MRI征象进行界定、观察、记录和统计学比较。结果57例骨髓炎患者中，CT检查54例，MR检查14例。CT检查的54例中，软组织肿胀52例（Ⅰ度19例、Ⅱ度16例、Ⅲ度17例），脓肿样囊腔6例，软组织肿块5例，软组织内气体、脂液平面和窦道各1例。MR检查的14例骨髓炎中，软组织肿胀14例（Ⅰ度2例、Ⅱ度6例、Ⅲ度6例），脓肿样囊腔（扩散加权成像均呈明显高信号）3例，软组织肿块和脂液平面各1例。70例恶性骨肿瘤患者中，CT检查54例，MR检查49例。CT检查的54例中，软组织肿胀44例（Ⅰ度29例、Ⅱ度12例、Ⅲ度3例），软组织肿块49例，软组织肿块边缘残留骨壳或壳样钙化16例，软组织肿块内肿瘤骨或瘤软骨钙化25例。MR检查的49例恶性骨肿瘤中，软组织肿胀46例（Ⅰ度21例、Ⅱ度17例、Ⅲ度8例），软组织肿块43例。骨髓炎组和恶性骨肿瘤组CT图像显示的软组织肿胀程度（Uc=4．1066，P〈0．01）以及脓肿样囊腔（X^2=4．4118，P〈0．05）、肿块（X^2=71．7037，P〈0．01）、肿块边缘残留骨壳或壳样钙化（X^2=18．7826，P〈0．01）和肿块内肿瘤骨或瘤软骨钙化（X^2=32．5301，P〈0．01）出现比例差异具有统计学意义。MR图像所示的软组织肿胀程度（Uc=2．5997，P〈0．01）以及脓肿样囊腔（四格表确切概率P=0．0092）和肿块（X^2=29．8757，P〈0．01）出现比例差异亦有统计学意义。结论 软组织肿胀程度和软组织肿块对骨髓炎和恶性骨肿瘤鉴别具有一定价值。软组织肿块边缘残留骨壳或壳样钙化以及软组织肿块内肿瘤骨或瘤软骨钙化是恶性骨肿瘤的特异性征象。脓肿样囊腔、软组织内气体、脂液征和窦道是骨髓炎的可靠征象。