Regional cerebral blood flow levels as measured by xenon-CT in vascular territorial low-density areas after subarachnoid hemorrhage are not always ischemic

Introduction The aim of this study was to assess regional cerebral blood flow (rCBV) in areas of CT hypoattenuation appearing in the postoperative period in patients treated for aneurysmal subarachnoid hemorrhage (SAH) using xenon-enhanced CT scanning (Xe-CT).Methods We analyzed 15 patients (5 male and 10 female; mean age 49.7±12.1 years) with SAH on CT performed on admission to hospital and who showed a low-density area within a well-defined vascular territory on CT scans after clipping or coiling of a saccular aneurysm. All zones of hypoattenuation were larger than 1 cm² and showed signs of a mass effect suggesting a subacute phase of evolution. Two aneurysms were detected in two patients. Aneurysms were located in the middle cerebral artery (n=7), in the anterior communicating artery (n=6), in the internal carotid artery (n=3), and in the posterior communicating artery (n=1). Treatments were surgical (n=8), endovascular (n=2) or both (n=1). A total of 36 Xe-CT studies were performed and rCBF values were measured in two different regions of interest (ROI): the low-density area, and an area of normal-appearing brain tissue located symmetrically in the contralateral hemisphere.Results rCBF levels were significantly lower in the low-density area than in the contralateral normal-appearing area (P<0.01). In the low-density areas, irreversible ischemia (CBF <10 ml/100 g per minute) was present in 11/36 lesions (30.6%), ischemic penumbra (CBF 10–20 ml/100 g per minute) and oligemia (CBF 20–34 ml/100 g per minute) in 8/36 lesions (22.2%), relative hyperemia (CBF 34–55 ml/100 g per minute) in 7/36 lesions (19.4%), and absolute hyperemia (CBF >55 ml/100 g per minute) in 2/36 lesions (5.6%).Conclusion Our study confirmed that rCBF is reduced in new low-density lesions related to specific vascular territories. However, only about one-third of the lesions showed rCBF levels consistent with irreversible ischemia and in a relatively high proportion of lesions, rCBF levels indicated penumbral, oligemic and hyperemic areas.     

Perirolandic hypoperfusion on single-photon emission computed tomography in term infants with perinatal asphyxia: comparison with MRI and clinical findings

We describe the findings on single-photon emission computed tomography (SPECT) in patients with perinatal asphyxia at term, with perirolandic cortico-subcortical changes on MRI, and to correlate them with clinical features. SPECT of 7 patients was obtained after injection of 185–370 MBq of Tc-99m-ECD (ethyl cysteinate dimer). The patients had spastic quadriplegia (7/7) with perinatal asphyxia (6/7) at term (7/7). The results were correlated with the MRI findings. Hypoperfusion of the perirolandic cortex was clearly seen on SPECT in all patients, even in two with subtle changes on MRI. SPECT demonstrated a more extensive area of involvement than MRI, notably in the cerebellum (in 4), the thalamus (in 7) and basal ganglia (in 5), where MRI failed to show any abnormalities. Received: 5 October 1999/Accepted: 11 November 1999     

De novo development of presumed cavernomas following resolution of E. Coli subdural empyemas

Cavernomas fall within the group of angiographically occult lesions and may be found in up to 4 % of the population [1]. They may occur at any age, and with the advent of MRI incidental cavernomas are increasingly identified. The pathogenesis is uncertain. Familial cases are well recognised with a reported prevalence of 10–15 % [2–3]. The incidence of new lesions has been reported at 0.4 lesions per patient per year in cases with familial cavernomas [4]. Presumed cavernomas have been documented following radiation for malignancy [5–6], and sterotactic cerebral biopsy [7]. There have been no previously documented cases of de novo genesis of cavernomas following bacterial meningitis and subdural empyemas. Received: 18 November 1999/Accepted: 11 February 2000     

MR findings of necrotic lesions and the extralesional area of osteonecrosis of the femoral head

Objective. To investigate the MR findings of necrotic lesions and the extralesional area of osteonecrosis of the femoral head (ONFH) for each of the radiological stages. Design and patients. Forty-nine hips in 29 patients (15 female, 14 male; mean age 38 years, range 17–59 years) were imaged using a 1.0-T superconducting magnet. T2-weighted spin echo pulse sequences (T2WI), spoiled gradient recalled echo pulse sequences (SPGR) and fat suppression SPGR (FS-SPGR), followed by Gd-DTPA enhanced fat suppression SPGR (Gd-FS-SPGR), were all obtained with the aid of a TORSO surface coil. Results and conclusions. While a normal fat intensity area with a low-intensity band on SPGR (band pattern) was seen in 16 of 16 stage 1 (100%), nine of 11 stage 2 (82%), four of 17 stage 3 (24%), and none of five stage 4 hips, all hips showed peripheral rim enhancement on Gd-FS-SPGR (100%). This enhancement band on Gd-FS-SPGR corresponded to histological findings of necrotic trabecular bone, repaired marrow, and fibrous reparative tissue. Bone marrow edema was also clearly demonstrated as a diffuse, high-intensity area outside this enhancement band on Gd-FS-SPGR in two stage 2 (18%), 12 stage 3 (71%), and one stage 4 hip (20%). In cases at stage 2 or more advanced stages with homogeneous or inhomogeneous low intensity on nonenhanced MRI, the reparative process both inside and outside the necrotic lesion, including bone marrow edema, was detected clearly on contrast- enhanced MRI. Received: 3 August 1999 Revision requested: 28 September 1999 Revision received: 11 November 1999 Accepted: 2 December 1999     

Multiple cerebral cavernous malformations: typical pattern on MR imaging and appearence of a new lesion in the follow-up MRI

Cerebral cavernous malformations (CCM) are common, mostly benign vascular anomalies of the CNS. Clinical features are seizures, headache and focal neurological signs. Often they are asymptomatic. Apart from sporadically cases CCM occur as an autosomal dominant condition. Familial cases are associated with a high frequency of multiple lesions. MRI is most sensitive in the detection of cavernous malformations. The MRI findings of CCM are variable, depending on hemorrhage and calcifications. The typical appearence of CCM are heterogenous "popcorn-like" lesions of different size with a mixed signal core and a hypointense hemosiderin rim. Our report concerns a 22 year old man with multiple cerebral cavernous malformations whose follow-up MRI of brain showed the appearence of a new lesion.     

Incidence of unilateral distal vertebral artery aplasia: evaluation by combining basiparallel anatomic scanning-magnetic resonance imaging (BPAS-MRI) and magnetic resonance angiography

Purpose  The incidence of a unilateral aplastic distal vertebral artery (VA) has been reported as 0.2% of cases on cerebral angiography. During our daily magnetic resonance (MR) examinations, however, we frequently encounter MR angiograms (MRAs) that do not demonstrate unilateral VA. The purpose of this study was to calculate the frequency of aplastic unilateral distal VA by MR images performed for asymptomatic people. Materials and methods  Over a time span of 1 year, 237 asymptomatic people (140 men, 97 women; ages 28–67 years, mean 54.4 years) underwent brain MRI during a “brain check-up examination” in our hospital. To identify an aplastic unilateral distal VA, we retrospectively compared three-dimensional time-of-flight MRA with basiparallel anatomic scanning (BPAS)-MRI which was designed for recognition of the arterial outer contour. Results  Aplasia of the unilateral distal VA was confirmed in 11 persons (4.6%). According to our classification, hypoplastic distal VA in 12 (5.1%) and asymptomatic acquired unilateral distal VA occlusion was also proved in 2 (0.8%). Conclusion  We found that the frequency of aplastic unilateral VA was 4.6% in asymptomatic people using a combination of MRA and BPAS-MRI for assessment of an intracranial VA.     

Preoperative evaluation of malignant liver tumors: comparison of unenhanced and SPIO (Resovist)-enhanced MR imaging with biphasic CTAP and intraoperative US

The purpose of this study was to evaluate the diagnostic efficacy of iron-oxide-enhanced MRI vs CT during arterial portography (CTAP) and intraoperative ultrasound (IOUS) in detection of liver neoplasms. Seventeen patients with malignant focal liver lesions (liver metastases, n=7), hepatocellular carcinomas (HCC, n=9), and cholangiocellular carcinoma (CCC, n=1) underwent presurgical Resovist-enhanced MRI and CTAP. Two independent observers (A and B) assessed the blinded images of unenhanced and iron-oxide-enhanced MRI vs CTAP for the presence, number, and location of the liver lesions. These results were compared lesion by lesion and segment by segment with the results of intraoperative ultrasound (n=17) serving as the reference standard. Eighty lesions were detected by intraoperative ultrasound in 17 patients. In comparison with IOUS (lesion-by-lesion analysis) the sensitivity was 86.8% for CTAP, 65% for combined unenhanced MR imaging, and 86.8% for combined Resovist-enhanced MRI as well as 86.8% for the combination of unenhanced and Resovist-enhanced MRI. Compared with the sensitivity of combined unenhanced MRI the sensitivity of CTAP as well as the sensitivity of combined Resovist-enhanced MRI was significantly higher (p<0.05). False-positive results were much higher in CTAP as compared with combined unenhanced and SPIO-enhanced MRI. Using the segment-by-segment analysis the specificity of combined unenhanced MRI with 100% (96.7–100%) as well as combined Resovist-enhanced MRI with 100% (96.7–100%) was significantly higher (p<0.05) in comparison with the specificity of CTAP with 91.1% (83.2–96.1%). The accuracy of combined unenhanced MRI was 100% (93.2–100%), combined Resovist-enhanced MRI 100% (93.6–100%) and of CTAP 85.2% (72.9–93.4%). In the detection of focal liver lesions iron-oxide-enhanced MR imaging is superior to unenhanced MRI and similar to CTAP. Electronic Publication     

Value of (18F)-FDG positron emission tomography, computed tomography, and magnetic resonance imaging in diagnosing primary and recurrent ovarian carcinoma

The aim of this study was to compare prospectively the accuracy of whole-body positron emission tomography (PET), CT and MRI in diagnosing primary and recurrent ovarian cancer. Nineteen patients (age range 23–76 years) were recruited with suspicious ovarian lesions at presentation (n = 8) or follow-up for recurrence (n = 11). All patients were scheduled for laparotomy and histological confirmation. Whole-body PET with FDG, contrast-enhanced spiral CT of the abdomen, including the pelvis, and MRI of the entire abdomen were performed. Each imaging study was evaluated separately. Imaging findings were correlated with histopathological diagnosis. The sensitivity, specificity and accuracy for lesion characterization in patients with suspicious ovarian lesions (n = 7) were, respectively: 100, 67 and 86 % for PET; 100, 67 and 86 % for CT; and 100, 100 and 100 % for MRI. For the diagnosis of recurrent disease (n = 10), PET had a sensitivity of 100 %, specificity of 50 % and accuracy of 90 %. The PET technique was the only technique which correctly identified a single transverse colon metastasis. Results for CT were 40, 50 and 43 %, and for MRI 86, 100 and 89 %, respectively. No statistically significant difference was seen. Neither FDG PET nor CT nor MRI can replace surgery in the detection of microscopic peritoneal disease. No statistically significant difference was observed for the investigated imaging modalities with regard to lesion characterization or detection of recurrent disease; thus, the methods are permissible alternatives. The PET technique, however, has the drawback of less accurate spatial assignment of small lesions compared with CT and MRI. Received: 9 April 1999; Revised: 22 June 1999; Accepted: 25 August 1999     

脑血管畸形磁共振血管成像与脑血管造影对照研究

目的：探讨了ＴＯＦ法ＭＲＡ评价脑血管畸形的价值及限度，材料与方法：２９例经ＭＲＩ（ｎ＝２９），脑血管造影（ｎ＝１５）和／或手术病理（ｎ＝１０）证实的脑血管畸形（ＡＶＭ２４例，ＡＶＦ２例，隐匿性ＡＶＭ３例）患者进行ＴＯＦ法ＭＲＡ检查，应用１．０Ｔ超导ＭＲ系统的二维或三维ＦＩＳＰ序列（预置０～３条预饱和带）和ＭＩＰ图像后处理技术，１５例同时经股动脉行全脑血管造影，采用Ｋａｐｐａ统计量对两种血管成像方法     

Efficacy evaluation of gadoteridol for MR angiography of intracranial vascular lesions

A phase III multicenter study was conducted in 89 patients with known intracranial vascular lesions to evaluate an extracellular gadolinium contrast agent, gadoteridol, for intracranial magnetic resonance (MR) angiography. The pre- and postcontrast MR angiograms of 82 patients were evaluated by the unblinded investigators and by two blinded readers (A and B) for visualization of lesions; arterial and venous anatomy; extent, size, and number of lesions; and disease classification. The unblinded readers indicated that lesions were visualized better on postcontrast images in the following categories: venous anatomy, 87 (81%) of 107 lesions; arterial anatomy, 43 lesions (40%); and extent or size of lesions, 38 lesions (36%). In 29 (35%) of 82 patients, the unblinded readers determined that enhanced MR angiography provided more diagnostic information than unenhanced MR angiography. The blinded readers determined that enhanced MR angiography provided more information for visualization of vascular anatomy in more than 60% of cases. The additional information provided with gadoteridol would have changed the diagnosis in nine (8%) of 107 lesions seen by the unblinded readers, 11 (12%) of 90 lesions seen by reader A, and three (3%) of 93 lesions seen by reader B. The results confirm that the use of gadoteridol improves the visualization of intracranial vascular lesions with MR angiography. The authors conclude that development of new postprocessing algorithms will improve the utility of contrast-enhanced MR angiography.     

Diagnosis of superior labral lesions: comparison of noncontrast MRI with indirect MR arthrography in unexercised shoulders

Objective To prospectively compare the accuracy of noncontrast magnetic resonance imaging (MRI) with indirect MR arthrography (I-MRa) of unexercised shoulders for diagnosis of superior glenoid labral lesions. Materials and methods Institutional Review Board approval and patient informed consent were obtained for this prospective study. Superior labral findings on shoulder MRI and unexercised I-MRa studies of 104 patients were correlated with findings at arthroscopic shoulder surgery. Two musculoskeletal radiologists independently reviewed the two sets of MR images while blinded to arthroscopic results. For each radiologist, the McNemar test was used to detect statistically significant differences between techniques. Results The superior labrum was intact in 24 and abnormal in 80 subjects. For detection of superior labral lesions by each radiologist, I-MRa was more sensitive (84–91%) than MRI (66–85%), with statistically significant improvement in sensitivity for one reader (p = 0.003). However, I-MRa was less specific (58–71%) than MRI (75–83%). Overall, accuracy was slightly improved on I-MRa (78–86%) compared with MRI (70–83%), but this difference was not statistically significant for either reader. Conclusion Compared with noncontrast MRI, I-MRa was more sensitive for diagnosis of superior glenoid labral lesions. However, the diagnostic value of I-MRa in shoulders remaining at rest is potentially limited by decreased specificity of the technique. The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.     

MRI of Enterovirus 71 myelitis with monoplegia

We report two boys diagnosed as having herpangina and hand-foot-mouth disease complicated by monoplegia during the outbreak enterovirus infection in Taiwan in 1998. Enterovirus 71 was identified in the stool and throat swab; neither polio nor Coxsackie viruses was identified. MRI showed unilateral lesions in the anterior horns of the spinal cord at T11–12 and C2–5. Although the MRI findings and sites of these lesions were similar to those of poliovirus-associated poliomyelitis, the virological data indicated that these boys were infected with enterovirus type 71. Received: 9 March 1999/Accepted: 7 May 1999     

The radiological manifestations of intramuscular haemangiomas in adults: magnetic resonance imaging,computed tomography and ultrasound appearances

Objective Intramuscular haemangiomas in adults may appear similar to soft tissue sarcomas on imaging. This study evaluates the imaging characteristics of intramuscular haemangiomas on magnetic resonance imaging (MRI), computed tomography (CT) and ultrasound. Subjects and methods Retrospective review of medical records, imaging and pathology details of 34 patients presenting with intramuscular haemangiomas was performed. Age of patient, size, site of lesion and type of imaging was recorded. Lesions were evaluated for calcification, presence of fat, outline, texture, vascularity, enhancement and involvement of local structures. Results There were 12 male and 22 female patients aged between 9 years and 90 years (mean 39 years). Twenty-two lesions involved muscles of the extremities and 12 involved muscles of the trunk. Mean duration of the lesions was long: 59.3 months (range 3–240 months), with an average size of 7.5 cm (1.5–15 cm). Imaging comprised 27 MR studies, seven CT scans, 19 ultrasounds, and eight plain films. All lesions were well defined, lobulated and heterogeneous. None showed local invasion. On MRI and CT, 93–100% showed the presence of fat and 100% showed vascular channels and enhancement on MRI, CT and ultrasound. Phleboliths were seen on four plain films (50%) and on the corresponding MR images. On MRI, 70% of lesions had mildly hyperintense signal on T1-weighted sequences and 96% had hyperintense signal on T2-weighted sequences (relative to skeletal muscle). Histopathology confirmed diagnosis in all cases, showing the presence of fat, medium/large vessels and skeletal muscle. Conclusion Intramuscular haemangiomas have characteristic appearances on MRI, CT and ultrasound. Long history, presence of fat, calcification and internal vessels should alert the radiologist to this diagnosis prior to biopsy.     

Diffusion-weighted imaging in ischaemic stroke: a follow-up study

Diffusion-weighted (DWI) echo-planar (EPI) MRI has been used for imaging acute ischaemic stroke. We used DWI and conventional spin-echo (SE) MRI to study the dynamics of ischaemic human stroke. We examined 30 patients (mean age 57.5 years, range 27–82 years, median 57 years) with a diagnosis of stroke. They were examined in the acute (120 min to 47 h, mean 15.3 h), subacute (8 days) and chronic (2–3 months) stages of ischaemia using clinical scores and MRI. Imaging was performed on an 1.5-T imager. Anisotropic DWI with diffusion gradients in all three axes, an isotropic tensor trace pulse DWI sequence and SE MRI were used. In all patients both DWI sequences showed a decrease in the apparent diffusion coefficient (ADC) in the acute stage, even when SE images did not reveal signal abnormalities. Clinical features correlated with lesion site but not size. The ADC was initially 19.6–43 % less than that of nonischaemic tissue and increased to normal after 7 days in conventionally treated patients and after 2–5 days in patients who underwent intra-arterial fibrinolysis. In the chronic stage the ADC rose by up to 254.4 %. In patients who did not undergo fibrinolysis DWI changes correlated with the final infarct size (P < 0.05). It was possible to differentiate acute from chronic ischaemic lesions. We conclude that DWI is a sensitive and practicable tool for detecting early cerebral ischaemia. It is possible to predict in the acute stage the final size of an infarct. DWI may be helpful for clinical decisions and for monitoring therapy. Received: 1 March 1999/Accepted: 13 July 1999     

Evaluation of tumor blood flow in musculoskeletal lesions: dynamic contrast-enhanced MR imaging and its possibility when monitoring the response to preoperative chemotherapy-work in progress

Purpose The objective of this study was to calculate tumor blood flow (TBF) in musculoskeletal lesions and to evaluate the usefulness of this parameter in differentiating malignant from benign lesions and monitoring the treatment response to preoperative chemotherapy. Materials and methods Altogether, 33 patients with musculoskeletal lesions underwent a total of 50 dynamic magnetic resonance imaging (MRI) examinations, including 28 on 9 patients undergoing preoperative chemotherapy. TBF was calculated using deconvolution analysis. Steepest slope (SS) was determined from the time–intensity curve during the first pass of contrast medium. Results TBF ranged from 2.7 to 178.6 mL/100 mL/min in benign lesions and from 15.4 to 296.3 mL/100 mL/min in malignant lesions. SS ranged from 0.5%/s to 31.8%/s for benign lesions and from 3.1%/s to 64.8%/sec for malignant lesions. TBF and SS did not differ significantly between benign and malignant lesions. Among the nine patients who underwent preoperative chemotherapy, TBF after chemotherapy was lower in good responders (11.7, 11.0, 7.9 mL/100 mL/min) (n = 3, tumor necrosis ≥90%) than in poor responders (23.4–141.5 mL/100 mL/min) (n = 6, tumor necrosis <90%). Conclusion TBF and SS cannot reliably differentiate malignant from benign lesions. However, they have potential utility in evaluating the preoperative treatment response in patients with malignant musculoskeletal tumors.     

Bone bruises detected by magnetic resonance imaging following lateral ankle sprains

Although bone bruises have been well described in the knee joint, little is known about their presence in the ankle joint. The present study attempted to document the association of bone bruises with lateral ankle sprains. Magnetic resonance (MR) images were obtained from 60 consecutive patients with lateral ankle sprains between April 1994 and June 1995. There were 29 men and 31 women, aged on average 25 years (range 12–68 years). All of the patients presented within 3 weeks of the sprain. MRI examinations were done within 3 weeks of the injury in 15, after 3–6 weeks in 21, and after 6–8 weeks in 24 cases. There were 28 first-time sprains, while 32 patients had suffered one or more sprains before the most recent one. Plain radiographs showed no evidence of osseous abnormality. Following the conventional MRI examination, magnetic resonance arthrography (MRA) was done by injecting 2 mM of gadolinium diethylene triamine penta-acetic acid (DTPA) into the joint under fluoroscopic control, and the same images were obtained again to search for ligamentous lesions. A total of 11 bone bruises were detected in 10 ankles. In this group of patients, there were 5 men and 5 women aged on average 27 years (range 12–50 years). Four MRI examinations were done within 3 weeks, while six were done 3–6 weeks after the injury. One ankle which had suffered one previous sprain and complete ruptures of anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) had two lesions (talus and navicula). In another recurrent case with complete ATFL and CFL ruptures, the lesion was found in the calcaneus. The remaining eight lesions were in the talus in eight ankles. The ligamentous lesions in these ankles included three complete ATFL and CFL ruptures, and four isolated ATFL ruptures; in one ankle there were no ligamentous lesions. The location of talar bruises was medial in six and lateral in three ankles. The incidence of bone bruises associated with isolated ATFL lesions was 16% (4/25). With combined ATFL and CFL lesions the incidence was 50% (5/10). The incidence of ankles with bone bruises and first-time and recurrent sprains was 7% (2/28) and 25% (8/32), respectively. The occurrence of bone bruises should be kept in mind following ankle sprains. Their clinical significance in the long term remains to be determined. Received: 11 May 1996 Accepted: 30 January 1997     

Interventional MR: interstitial therapy

The rationale and results for interstitial therapies via interventional MRI in the treatment of tumors in various regions are presented. Different interstitial treatment techniques are presented based on varying technologies both for tumor ablation and treatment monitoring. Data are presented based on 335 patients, 29–84 years of age (mean age 59 years, 196 men and 139 women) with a total of 932 liver tumors, 16 head and neck tumors and 14 abdominal recurrent pelvic and lymphatic tumors. All lesions had been treated with MR-guided laser-induced interstitial thermotherapy (LITT) via 2516 laser applications and 1856 cannulations. Data in the literature are extremely varying depending on author experience, treatment technique, and the included patient material. In our patient material we were able to achieve a local tumor control of 96.7 % depending on the size of the tumorous lesion, the topographical relationship, and the applied laser parameters. The overall cumulative survival rate of patients with liver metastases was 45.74 months (median 40.97 months, 95 % confidence interval 31.42–50.52). The cumulative survival rate of the patient group with hepatic metastases of colorectal carcinoma was 42.71 months (median 39.33 months, 95 % confidence interval 33.26–45.37). In patients with head and neck tumors a relevant reduction in clinically relevant symptoms such as pain, swallowing disorders, or nervous compression was achieved in 11 of 15 patients treated with LITT. In 14 soft tissue tumors, such as pelvic tumor recurrence and lymph node metastases, a local tumor control was obtained in 68 % of lesions. Interstitial therapies under interventional MRI guidance, such as LITT, results in a high local tumor control with an improved survival rate.     

Triple-dose contrast-enhanced images in neurologically symptomatic HIV-positive patients

Our purpose was to determine whether triple-dose delayed contrast-enhanced images would improve lesion detection in patients with symptomatic human immunodeficiency virus (HIV) infection. We reviewed 33 MRI studies on 29 patients. Single-dose immediate T 1-weighted spin-echo (1x-T 1) images were compared with delayed triple-dose images (D3x-T 1). Two neuroradiologists decided which technique showed more lesions, increased lesion conspicuity and/or altered the radiologic diagnosis. The D3x-T 1 technique improved lesion detection in 14 of 29 patients (48 %). In two patients (7 %), the improvement changed the radiologic diagnosis by showing new meningeal lesions. Received: 1 February 1999 Accepted: 11 August 1999     

Chronic post-traumatic osteomyelitis of the lower extremity: comparison of magnetic resonance imaging and combined bone scintigraphy/immunoscintigraphy with radiolabelled monoclonal antigranulocyte antibodies

Objective. A retrospective study of the validity of combined bone scintigraphy (BS) and immunoscintigraphy (IS) using ^99mTc-labelled murine antigranulocyte antibodies (MAB) and magnetic resonance imaging (MRI) in chronic post- traumatic osteomyelitis. Design and patients. The results of MRI and combined BS/IS of 19 lesions in 18 patients (13 men, 5 women; mean age 45 years, range 27–65 years) were independently evaluated by two radiologists and one nuclear medicine physician with regard to bone infection activity and extent. The patient group was a highly selective collection of clinical cases: the average number of operations conducted because of relapsing infection was eight (range 2–27), the average time interval between the last surgical intervention and the present study was 6.5 years (range 3 months to 39 years), and from the first operation was 14 years (range 1.5–42 years). Interobserver agreement on MRI was measured by kappa statistics. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated for MRI and the nuclear medicine studies. Results. For MRI/nuclear medicine, a sensitivity of 100%/77%, a specificity of 60%/50%, an accuracy of 79%/61%, a PPV of 69%/58% and a NPV of 100%/71% were calculated. Four MR examinations were false positives because of postsurgical granulation tissue. A high degree of interobserver agreement was found on MRI (κ=0.88). A low-grade infection was missed on two scintigrams, while four were false positive because of ectopic haematopoietic bone marrow, and in one examination the anatomical distortion resulted in an inaccurate assignment of the uptake leading to false positive findings. Image analysis was frequently hindered by susceptibility artefacts due to residual abrasions of metallic implants after removal of orthopaedic devices (15/18 patients); this led to limited assessment in 17% (3/18 patients). Conclusion. Acute activity in a chronic osteomyelitis can be excluded with high probability if the MRI findings are negative. In the first postoperative year fibrovascular scar cannot be distinguished accurately from reactivated infection on MRI and scintigraphy may improve the accuracy of diagnosis. MRI is more sensitive in low-grade infection during the later course than combined BS/IS. Scintigraphic errors due to ectopic, peripheral, haematopoietic bone marrow can be corrected by MRI. Received: 17 December 1999 Revision requested: 25 January 2000 Revision received: 15 March 2000 Accepted: 4 April 2000