Clement Kuen-Huang Chen

Intra-articular gouty tophi of the knee: CT and MR imaging in 12 patients

Abstract Objective. To define the imaging characteristics of intra-articular tophi of the knee. Design and patients. Twelve patients with intra-articular tophi in the knee were studied with routine MR imaging, gadolinium (Gd)-enhanced MR imaging, and CT over a 4-year period. There were 11 men and one woman, 25–82 years of age (mean age 48 years). Four patients did not have a documented history of gout at the time of the MR examination. The diagnosis of intra-articular tophi was provided by arthroscopy and histological examination (5 patients), by microscopic study of joint fluid (5 patients), or by characteristic clinical, laboratory and imaging findings (2 patients). Results. In 15 MR examinations the tophi were located purely intra-articularly in 10 knees. In the remaining five MR studies, periarticular soft tissues or bone, or both, were involved. All the intra-articular tophi manifested low to intermediate signal intensity on both T1- and T2-weighted images. All five Gd-enhanced MR examinations demonstrated a heterogeneous peripheral enhancement. All 10 CT scans showed varying degrees of stippled calcifications within the tophi. The nature of the calcifications was confirmed on histological examination in three patients. Conclusion. Presenting clinical manifestations of gout may relate to intra-articular tophaceous deposits. Such deposits present as masses on MR images with low to intermediate signal intensity on both T1- and T2-weighted images and a characteristic enhancement pattern following intravenous Gd administration. These features relate primarily to internal calcifications, which are most evident on CT images. MR evaluation (including Gd administration) supplemented, in some cases, with CT scanning allows accurate diagnosis of intra-articular tophaceous deposits.

Detection of Subarachnoid Hemorrhage at Acute and Subacute/Chronic Stages: Comparison of Four Magnetic Resonance Imaging Pulse Sequences and Computed Tomography

Background: Acute subarachnoid hemorrhage (SAH) has traditionally been diagnosed by computed tomography (CT); however, fluid‐attenuated inversion recovery (FLAIR) is a magnetic resonance imaging (MRI) modality currently used to detect acute SAH. CT is insensitive in the detection of subacute or chronic SAH. The purpose of this study was to compare 4 MRI pulse sequences and CT in the detection of SAH in acute and subacute‐to‐chronic stages. Methods: From 2001‐2003, we collected data for 22 patients (12 men and 10 women, aged 35‐80 years) with SAH due to ruptured aneurysm (n = 11), trauma (3), or unknown origin (8). All patients underwent MRI and CT examination, with an interval of less than 12 hours between the 2 procedures. We divided patients into 2 groups according to the time from symptom onset to MRI evaluation: patients with MRI performed less than or equal to 5 days post‐ictus had acute‐stage illness, whereas patients with MRI performed from day 6‐30 post‐ictus had a subacute‐to‐chronic condition. MRI (1.5‐T) pulse sequences comprised spin‐echo T1‐weighted, fast spin‐echo T2‐weighted, FLAIR, and gradient‐echo (GE) T2*‐weighted images. Results: In the acute‐stage group, SAH was seen as an area of high signal intensity compared with surrounding cerebrospinal fluid in 36.4% of cases on T1‐weighted images, and in 100% on FLAIR images; low signal intensities were seen in 18.2% of cases on T2‐weighted images, and in 90.9% on GE T2*‐weighted images. High‐attenuated SAH was seen on CT in 90.9% of cases. FLAIR (p = 0.008), GE T2*‐weighted images (p = 0.012) and CT images (p = 0.012) were all statistically significant indicators of acute SAH. In the subacute/chronic‐stage group, SAH was detected on T1‐weighted images (36.4% of cases), FLAIR (33.3%), T2‐weighted images (9.1%), GE T2*‐weighted images (100%), and CT (45.5%). GE T2*‐weighted images were significantly superior (p = 0.001) to other MRI pulse sequences and CT as indicators of subacute‐to‐chronic SAH. Conclusion: FLAIR and GE T2* MRI pulse sequences, and CT scans, are all statistically significant indicators of acute SAH. GE T2*‐weighted images are statistically significant indicators of subacute‐to‐chronic SAH, whereas other MRI pulse sequences, and CT scans, are not.

Acute Community-acquired Osteoarticular Infections in Children: High Incidence of Concomitant Bone and Joint Involvement

BACKGROUND/PURPOSE Pediatric acute osteoarticular infections remain a challenging clinical issue for physicians. This paper provides recent clinical experiences on acute community-acquired osteoarticular infections in children in Taiwan. METHODS Children with acute community-acquired osteoarticular infections admitted to hospital were retrospectively reviewed and the findings compared with related infections in Taiwan published during the past 10 years. RESULTS We enrolled 27 children in our study, and reviewed 692 patients reported from six major studies in Taiwan. Of the 27 patients, 15 (55.6%) had concomitant bone and joint involvement. Blood cultures were positive in 44.4% of the children in this study and 48-52% in the other studies. Pathogens could be identified in 66.7% of our children and 63-76% in the other studies, when surgical specimens were available for culture. Staphylococcus aureus was consistently the most common pathogen found in all studies. Of the S. aureus isolates, methicillin-resistant S. aureus accounted for 13.3% in our study and 22-24% in the others. CONCLUSION Concomitant osteomyelitis and septic arthritis occurred in over half of our patients. The long-term effect of combined bone and joint infection on bone growth remains to be determined. Surgical intervention remains an important component of management of osteoarticular infections. Our findings are consistent with current recommendations of aggressive microbiology diagnosis and initiation of empirical monotherapy with oxacillin or oxacillin plus an agent effective against Gram-negative bacteria in most cases of community-acquired osteoarticular infections.

Percutaneous transsplenic catheterization of the portal venous system

Purpose: to evaluate the safety and feasibility of transsplenic portal vein catheterization. Material and Methods: Under ultrasonic guidance, percutaneous transsplenic splenic vein catheterization was performed in 17 patients. Two of the patients had minimal and 5 moderate ascites. in 11 patients, the platelet counts were over 50000/mm3 and the coagulation time normal or mildly prolonged, while 6 patients had either platelet counts of less than 50000/mm3 or moderately prolonged coagulation level. Results: Transsplenic portal catheterizations were successfully performed in 16 of the 17 patients (one failed because of small splenic size). Procedure-related complications occurred in 3 patients with 2 requiring one unit of packed RBC transfusion. the third patient accumulated minimal fluid in the left pleural space. Imaging studies within one week of the procedure were made in 8 patients. These examinations revealed an intrasplenic hematoma in 2 patients. One patient had a small amount of hemoperitone-um. No major complications occurred. Conclusion: Transsplenic portal venous catheterization is a safe and feasible procedure.

Posterior Reversible Encephalopathy Syndrome: Magnetic Resonance Imaging and Diffusion-Weighted Imaging in 12 Cases

Posterior reversible encephalopathy syndrome (PRES) is a potentially devastating neurologic syndrome, but timely treatment may lead to complete reversal of the disease course. We reviewed 12 cases of PRES and describe the clinical history and imaging findings, including conventional magnetic resonance imaging (MRI), diffusion‐weighted imaging (DWI), and calculated apparent diffusion coefficient (ADC) maps, used to establish the diagnosis of PRES. Three male and nine female patients aged between 11 and 70 years (mean, 37 years) with clinical and imaging findings consistent with PRES were enrolled in the study. All patients had undergone conventional MRI and 10 had undergone additional DWI studies. Ten patients had follow‐up MRI studies. DWI was performed using a 1.5T system with a single‐shot spin‐echo echo‐planar pulse sequence. Initial and follow‐up neuroimaging and clinical history were reviewed. Lesions were almost always present over the posterior circulation, mainly the parieto‐occipital region, affecting primarily the white matter. The anterior circulation region, brainstem, cerebellum, deep cerebral white matter, and thalamus were also involved in five cases. Conventional MRI revealed hyperintensity on T2‐ weighted and fluid‐attenuated inversion recovery images. DWI showed isointensity and increased signal intensity on ADC values in all cases, indicating vasogenic edema. Clinical and MRI follow‐up showed that the symptoms and radiologic abnormalities could be reversed after appropriate treatment of the causes of PRES in most patients (9 of 10). In one patient, the ADC value was lower on follow‐up images, indicating cytotoxic edema with ischemic infarct. DWI was a useful complement to MRI in the diagnosis of PRES.

Isolated intraosseous gout in hallux sesamoid mimicking a bone tumor in a teenaged patient

We are reporting an unusual case of isolated intraosseous tophus in medial hallux sesamoid presenting as tumor-like lesion in a teenage patient without prior history of gouty attack and underlying systemic disorders. The lesion manifested isointensity to surrounding muscles with internal low signal on spin echo (SE) T1-weighted images, and heterogeneous low signal intensity on fast spin echo (FSE) T2-weighted images. Computed tomography (CT) scan disclosed expansion and diffusely increased attenuation of the medial hallux sesamoid with focal cortical erosion and extraosseous extension of high attenuation content. The subsequent resection and pathology revealed intraosseous tophus deposition, which is particularly rare at this site and at this age. Imaging studies revealed some characteristic imaging features which can retrospectively be attributed to gouty tophus. When an expansile osteolytic lesion manifesting low signal intensity on T2-weighted image and internal calcifications on CT scan is encountered, the possibility of intraosseous tophus should be included in the list of differential diagnoses, even in a teenage patient without prior history of gout.

A case of spontaneous intracranial hypotension complicated by isolated cortical vein thrombosis and cerebral venous infarction.

Intracranial hypotension is a syndrome of low cerebrospinal fluid (CSF) pressure characterized by postural headache (1). It may occur following lumbar puncture, craniotomy, spinal surgery, or spontaneously – so-called spontaneous intracranial hypotension (SIH). The diagnosis of SIH can be challenging. Recent reports have emphasized intracranial magnetic resonance (MR) findings in SIH (1–4). However, SIH complicated by cerebral sinus venous thrombosis has been mentioned rarely in the literature (5, 6). We present a rare case of SIH complicated by isolated cortical vein thrombosis (ICVT) and cerebral venous infarction. Therapy with epidural blood patch and intravenous heparin was successful.

Comparison of plain MRI and MR arthrography in the evaluation of lateral ligamentous injury of the ankle joint

Background: The purpose of this study was to determine the efficacy of plain magnetic resonance imaging (MRI) and magnetic resonance (MR) arthrography for detecting collateral ligamentous injury of the ankle joint. Methods: Fifty patients (October 2001 to November 2003) suffering from ankle disability who underwent plain MRI and MR arthrographic studies were enrolled in this study. The diagnostic criteria for ligament disruption on plain MRI included nonvisualization, disruption, waviness of the ligament, or coexistent avulsion fracture. The MR arthrographic findings of ligament disruption were based on leakage of gadolinium contrast medium anterior to the anterior talofibular (ATaF) ligament following ATaF ligament disruption, and the contrast medium filling into the common peroneal tendon sheath after calcaneofibular (CF) ligament disruption. The 2 modalities were interpreted respectively and blindly. Results: Seventeen patients received surgical intervention. There were 14 patients who had a torn ATaF ligament and 6 patients who suffered from CF ligament disruption proved by surgery. Limited detection of preoperative plain MRI survey, which showed 12 patients had torn ATaF and 2 patients had torn CF ligament, was noted. However, most patients with ligamentous injury were correctly diagnosed by MR arthrography preoperatively (only 1 case of CF injury was missed). The plain MRI alone had a higher incidence of false negative and false positive detection. MR arthrography was also valuable for evaluating the coexisting intra‐articular pathologies of the ankle joint. Conclusion: For evaluating ankle disability, using plain MRI alone is not adequate for correctly detecting lateral collateral ligamentous injury of the ankle joint. MR arthrography improves the sensitivity and the accuracy for ATaF and CF ligament injuries. It also helps in assessing coexisting pathologic lesions of ankle joints, especially impingement syndromes and osteochondral lesions, and provides more information for therapeutic decision making.

Cerebral Pilocytic Astrocytoma with Spontaneous Intracranial Hemorrhage in Adults

Pilocytic astrocytomas are found predominantly in the pediatric population; reports of these tumors are extremely rare in adults. We report 2 cases of adult pilocytic astrocytoma with intracranial hemorrhage. A 32-year-old male presented with neck stiffness and severe headache, and a 34-year-old male was referred for headache and double vision. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a well-enhanced and circumscribed cystic hemorrhagic tumor with mural nodule over the cerebral hemisphere region. Perfusion-weighted MRI (PWI) was also performed in both patients. The measured relative cerebral blood volume ratios of the mural nodules in these 2 cases were, respectively, 1.34 and 2.81 when compared with normal white matter. After surgical resection, microscopic examination of the lesions showed pilocytic astrocytomas. Since pilocytic astrocytoma and other cystic tumors with mural nodule (such as hemangioblastoma) have similar findings on conventional CT and MRI, PWI is helpful in the differential diagnosis. The literature on hemorrhagic pilocytic astrocytoma is also reviewed.

MRI Diagnosis of Fibrolipomatous Hamartoma of the Median Nerve and Associated Macrodystrophia Lipomatosa

Fibrolipomatous hamartoma is an uncommon congenital disorder, which is characterized by disproportionate hyperplasia of adipose tissue infiltrating along the perineurium, the epineurium and the affected nerve trajectory. We present a case of combined fibrolipomatous hamartoma and macrodystrophia lipomatosa of the median nerve. The involved sites included the left palm, wrist and forearm. Part of the patients middle finger had been amputated due to previous macrodystrophia lipomatosa; however, the lesion continued to enlarge and was accompanied by numbness. Magnetic resonance imaging demonstrated a typical fibrolipomatous hamartoma with high signal intensity of fat on both T1-weighted and T2-weighted images, characteristic coaxial cable appearance on axial images, and spaghetti appearance on sagittal images. A similar skipped lesion at the median nerve of the middle forearm was also noted. To the best of our knowledge, this has not been reported in the English literature.