Longitudinal stress fractures of the tibia: comparative study of CT and MR imaging

The aim of this study was to compare the performance of CT and MRI in the diagnosis of longitudinal stress fracture of the tibia (LSFT). A retrospective study of imaging findings was performed in 15 patients with LSFT. The CT and MR images were compared for detection of fracture line, callus, bone marrow edema, and soft tissues changes. The CT and MRI techniques allowed the detection of the fracture line in 82 and 73 % of cases, respectively. The callus was always visualized with CT or MRI. The MRI technique had a markedly higher sensitivity than CT in the detection of bone marrow edema (73 vs 18 %) and soft tissue lesions (87 vs 9 %). This may cause a misleading aggressive appearance on MRI. Computed tomography remains the best imaging modality for diagnosis of LSFT. However, MRI findings should be known to obviate the performance of CT or bone biopsy. Received 26 May 1997; Revision received 1 October 1997; Accepted 13 November 1997     

眶内囊虫病的影像学诊断

目的 总结眶内囊虫病的影像学表现，评价Ｂ超、ＣＴ和ＭＲＩ对其诊断的优势与限度。方法 将６例眶内囊虫病者的Ｂ超、ＣＴ和ＭＲ影像学表现与手术病理结果进行对照分析。结果 眶内囊虫病在眶内形成肉芽肿。Ｂ超见肿块内有低回声液性暗区（囊泡）和点状强回声头节，并可见特异性虫体蠕动；ＣＴ可见点状高密度头节和低密度囊泡影，ＣＴ对头节的显示率较Ｂ超高；ＭＲＩ对头节显示不清，仅可见囊光，但对眶内囊虫病累及范围和程度的显     

Subcutaneous and musculoskeletal sparganosis: imaging characteristics and pathologic correlation

Objective. To document the imaging characteristics of subcutaneous and musculoskeletal sparganosis. Design and patients. Ten patients with musculoskeletal sparganosis were examined, with a variety of imaging modalities including MRI (n=6), ultrasonography (n=8), plain radiography (n=7) and CT (n=1). Pathologic correlation was carried out in all cases. Results. Nine lesions involved soft tissues, of which seven were in the thigh, two in the trunk and one involved a vertebral body. The majority of the lesions in soft tissue were confined to the subcutaneous layer but two extended deep into underlying muscles. Sonography revealed low-echoic serpiginous tubular tracts (8/8), and an intraluminal echogenic structure (4/8). MRI revealed multiple serpiginous tubular tracts and peripheral rim enhancement. Two patients showed perilesional soft tissue edema. Pathologically, the lesion consisted of a larva surrounded by three layers of inflammation: an inner epithelioid granulomatous cell layer, middle chronic inflammatory cell layers, and an outer fibrous layer. Conclusion. The study suggests that if serpiginous tubular tracts are seen at imaging studies, musculoskeletal sparganosis should be included in the differential diagnosis. Received: 27 July 1999 Revision requested: 20 September 1999 Revision received: 11 February 2000 Accepted: 14 March 2000     

Proliferative myositis in a child

A case of proliferative myositis in the lumbar paraspinal muscles in a 14-year-old boy is presented. Imaging investigations including plain radiograph, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), bone scan and positron emission tomography (PET) were suggestive of an inflammatory process such as myositis ossificans. The diagnosis was made by incisional biopsy. More pronounced edema, more muscle fiber necrosis and a higher cellularity were found compared to adult cases. The karyotype of the lesion was normal. Clinically, the mass disappeared spontaneously. After 24 months, asymptomatic bridging ossification between the third and fourth lumbar vertebrae was noted. Received: 18 February 1999 Revision requested: 29 March 1999 Revision received: 23 August 1999 Accepted: 24 August 1999     

MRI of the breast: state of the art

Contrast-enhanced MRI of the breast is probably the most sensitive method to detect breast pathology. It is best used to improve the sensitivity of mammography and sonography in selected patient groups with high breast cancer prevalence, where conventional methods are known to be less sensitive. Despite the high sensitivity of MRI, 5–12 % of invasive carcinomas are not recognized during MRI, because of lack of the typical criteria of carcinoma. MRI is probably inferior to mammography in detecting ductal in-situ carcinoma or very small carcinomas (< 3 mm), because the neo-angiogenesis induced by these small carcinomas is too faint to be detected by contrast-enhanced MRI. These tumours cannot be excluded by a normal MRI examination. MRI is non-specific as the distinction of benign and malignant breast lesions is unreliable. Only in selected cases (fat- or blood-containing lesions) may it improve the specificity of mammography and sonography. Mostly image-guided core biopsy is by far the most specific and least expensive method to establish a definitive diagnosis. For lesions exclusively detected by contrast-enhanced MRI, simple and reliable localisation devices are urgently needed. Presently accepted indications for MRI of the breast are: patients with silicone implants after mastectomy or augmentation mammoplasty (detection of recurrence/prothesis rupture/silicon leakage); patients whose breasts are difficult to evaluate by combined mammography and sonography, who have had breast conservation therapy (local recurrence), or who have proven carcinoma in one breast (multifocality/-centricity or contralateral breast carcinoma) or proven axillary lymph node metastases from an unknown primary tumor, especially when these are hormone receptor positive; patients with extensive postoperative scarring. In the future, genetically defined high breast cancer risk may become an indication. Received 7 October 1997; Revision received 14 November 1997; Accepted 17 November 1997     

Subchondral insufficiency fracture of the femoral head: histopathologic correlation with MRI

Objective. To correlate the magnetic resonance imaging (MRI) features with the histopathologic findings in subchondral insufficiency fracture (SIF) of the femoral head. Design and patients. This study was based on a retrospective review of the MRI features and histopathologic findings in seven patients with SIF who had had total hip replacement. Results. In all seven cases, MRI showed a bone marrow edema pattern in the femoral head, and a focal low-intensity band beneath the articular cartilage on some slices (not all) on the T1-weighted images. The shape of the low-intensity band varied: it was irregular and serpentine in four cases, well-delineated, smooth, and a mirror image to the articular surface in two cases, and parallel to the articular surface in one case. On histologic examination, the low-intensity band on MRI corresponded to a fracture line and its associated repair tissue. In all but one case, the band was not visible on T2-weighted or fat suppression images, and the proximal subchondral portion of the lesion had a homogeneous high signal intensity. This region of high signal intensity corresponded histopathologically to viable bone and marrow tissue with associated callus, edema, and vascular granulation tissue. Conclusions. SIF of the femoral head characteristically demonstrates a low-intensity band on T1-weighted images that corresponds, histopathologically, to a linear subchondral fracture and its associated repair tissue. In most cases, the subchondral portion of the lesion appears on T2-weighted images as an area of homogeneously high signal intensity. Received: 1 June 2000 Revision requested: 17 August 2000 Revision received: 11 October 2000 Accepted: 9 January 2001     

Hepatic hemangiomas with arterioportal shunt: sonographic appearances with CT and MRI correlation

OBJECTIVE: The purpose of this study was to summarize and illustrate the sonographic appearance of hepatic hemangiomas with arterioportal shunt and to correlate them with CT and MRI findings. CONCLUSION: High-flow hepatic hemangiomas tend to be seen as hypoechoic lesions at sonography. In the presence of fatty infiltration in the liver, they may accompany peritumoral low-echoic areas presumably caused by peritumoral sparing of fatty infiltration similar to a hyperattenuating or hyperintense peritumoral rim on unenhanced CT or MR chemical shift imaging. Color Doppler sonography may reveal intratumoral flows, large feeding arteries, and reversal of portal flow around the tumor. Knowledge of such sonographic findings may ensure an accurate sonographic diagnosis of these tumors.     

Transcranial color Doppler sonography in the emergency diagnosis of middle cerebral artery occlusion in a patient after head injury

The purpose of this report is to highlight the utility of transcranial color Doppler sonography (TCCDS) in the emergency diagnosis of an ischemic stroke in a 64-year-old patient after head injury. An emergency CT identified a subdural hematoma, subarachnoid hemorrhage, a brain contusion and edema. The patient's status deteriorated after admission, and a second CT revealed an intracerebral hematoma and marked mass effect. Transcranial color sonography revealed no flow in the ipsilateral middle and anterior cerebral arteries, which was consistent with ischemic stroke. This case demonstrates that transcranial color Doppler sonography performed early after head injury may be useful in detecting associated occlusion of cerebral vessels.     

PET, CT, and MRI in the evaluation of neuropsychiatric disorders: current applications

Positron emission tomography (PET) is emerging as a very useful clinical tool and is adding a great deal to our understanding of the pathophysiology of central nervous system (CNS) disorders. Although computed tomography (CT) and magnetic resonance imaging (MRI) have had a dramatic impact on patient management, there is often an important associated function abnormality which is best assessed by PET. In normal aging and in dementia, the CT and MRI brain changes of atrophy and white matter abnormalities are frequently nonspecific. PET has been more diagnostic, showing characteristic regional metabolic abnormalities. Evaluation of brain tumors such as astrocytomas with PET has demonstrated better correlation with histologic grade compared to CT. Unlike CT or MRI, PET can help to distinguish radiation necrosis from recurrent tumor, and can differentiate the extent of metabolically active tumor from surrounding edema. PET is useful in evaluating stroke patients, providing better prognostic information and demonstrating abnormalities sooner than CT. In epilepsy, PET appears to be superior to MRI in localizing seizure foci in patients with partial seizures. In head trauma patients, metabolic patterns are being described which will likely have an effect on patient management. The use of PET in schizophrenia has yielded very interesting results, with common patterns of metabolic abnormalities being demonstrated. CT and MRI in these patients have not been very useful. PET has also shown promise in movement disorders such as Huntington's disease. It is now clear that PET is already clinically useful and can provide valuable information unobtainable by CT and MRI. As new radioligands are developed, PET is certain to assume an even more important role in the future.     

Reconstruction of the sternum and chest wall with methyl methacrylate: CT and MRI appearance

The aim of our study was to define the appearance of methyl methacrylate grafts replacing resected sternum and ribs on CT and MRI and how the sternal graft may mimic an abnormally sclerotic sternum on CT images. We reviewed the CT scans of nine patients who had undergone chest wall resection (eight with malignant and one with benign disease) and reconstruction with a composite of methyl methacrylate and Marlex mesh graft. One of them had an MRI study as well. The size, shape and CT attenuation were assessed on mediastinal and bone window settings. The sternal graft was seen on mediastinal and even better on bone windows as an abnormally wide, irregularly shaped structure, somewhat denser than the normal sternum. The chest wall prosthesis replacing resected ribs was seen as a continuous dense structure and of similar attenuation as that of the sternal graft. On MRI the prosthesis appeared as a well-defined structure with no signal. Reconstruction of the chest wall with methyl methacrylate appears on CT as a diffusely dense sclerotic bone lesion not unlike a malignant lesion. The possibility of a graft has to be included in the differential diagnosis in these cases. Received 8 January 1997; Revision received 23 May 1997; Accepted 4 July 1997     

Hyperplastic callus formation in osteogenesis imperfecta: CT and MRI findings

Hyperplastic callus formation is a noteworthy condition in patients with osteogenesis imperfecta because it often mimicks osteosarcoma on radiography. The findings of CT and MRI in hyperplastic callus formation have not been reported. In the presented case, MRI demonstrated contrast enhancement and edema of the surrounding soft tisssue, consistent with benign as well as malignant disease. Computed tomography showed a calcified rim of the lesion which may be a useful feature to rule out osteosarcoma in this condition. Received 7 August 1997; Revision received 17 November 1997; Accepted 24 December 1997     

Diagnostic value of MR imaging in comparison to CT in the detection and differential diagnosis of renal masses: ROC analysis

The aim of this work was to compare MR imaging and CT in the detection of renal masses and in the differential diagnosis between benign and malignant lesions. In 33 patients with 54 renal lesions CT and MR images were evaluated by four readers with regard to tumor detection and characterization using a receiver-operating-characteristics (ROC) analysis. The MRI protocol consisted of a T1-weighted spin-echo (SE) sequence (TR/TE: 300/10 ms) before and after contrast administration and a heavily T2-weighted turbo-SE (TSE) sequence (TR/TE: 5500/150 ms). A_z values for the area under the ROC curves for lesion detection were 0.92 ± 0.04 for CT and 0.91 ± 0.05 for MRI, respectively, which was not statistically different. The MRI technique was slightly, but not significantly, better than CT in the overall characterization (accuracy in differentiation between benign and malignant) of renal lesions with an A_z value of 0.90 ± 0.05 compared with 0.88 ± 0.06 for CT. The MRI technique proved to be statistically superior to CT (p < 0.01) in the correct characterization of benign renal lesions. MRI equals CT in the overall detection and differential diagnosis of renal masses. MRI is very helpful for further differential diagnosis of lesions which are equivocal on CT especially in the differentiation between complicated cysts and cystic or hypovascular renal cell carcinoma. Received 29 April 1996; Revision received 14 August 1996; Accepted 2 September 1996     

Multiple renal aspergillus abscesses in an AIDS patient: contrast-enhanced helical CT and MRI findings

Renal insufficiency or allergic reactions for X-ray contrast agents are frequent limitations in immunocompromised hosts such as neutropenic or AIDS patients. Due to a better tolerance of contrast agents in MRI, this technique is well suited for investigation of parenchymal organs. We demonstrate an allergic AIDS patient who presented with fever and flank pain. At sonography, anechoic renal lesions were supposed to be non-complicated cysts; however, on T2-weighted MRI, the center was of high signal. Dynamic contrast-enhanced MRI of the kidneys demonstrated an enhancing rim with ill-defined margins. The lesions were supposed to be multiple bilateral abscesses. Due to the multiple dynamic contrast series, a delayed enhancement of renal parenchyma was detectable adjacent to the lesion. This was suggested as accompanying local pyelonephritis and an infectious etiology became more reliable. Aspergillus fumigatus was identified by CT-guided biopsy as the underlying microorganism. The MR appearance of this manifestation has not been described previously. Received: 8 June 1998; Revision received: 7 August 1998; Accepted: 26 August 1998     

MRI of acute spinal trauma

The clinician managing patients who have suffered trauma to the spine requires several questions answered from imaging studies. In the acute stage, a full assessment of the complete injury to the bony, ligamentous, disc and neural tissues will determine the stability of the injury and help decide the nature of clinical management, either conservative or surgical, and also help in determining the surgical approach. Magnetic resonance imaging (MRI) is established as a vital imaging technique and can answer many of the questions posed above. The purpose of this article is to review the current status of MRI in the assessment of acute spinal trauma. Received: 24 August 2000 Revision requested: 13 December 2000 Revision received: 31 January 2001 Accepted: 15 February 2001     

Unusual facet cyst containing struvite and hydroxyapatite

This case report describes a patient with severe back pain and radiculopathy. She was found to have a facet cyst within the lumbar spine that appeared to contain calcium on MRI and CT. Upon aspiration the cyst was found to contain calcium ammonium phosphate (struvite) and calcium phosphate (hydroxyapatite). Ammonia production in the presence of urease-producing bacteria is responsible for the production of struvite in the human body. We postulate that there was a prior infection of the facet with urease-producing bacteria, thus accounting for the production of the struvite within the facet cyst. Received: 29 June 2000 Revision requested: 18 August 2000 Revision received: 27 September 2000 Accepted: 27 September 2000     

Pancreatic adenocarcinoma

Adenocarcinoma is the most common malignant pancreatic tumor, affecting the head of the pancreas in 60–70% of cases. By the time of diagnosis, at least 80% of tumors are unresectable. Helical computed tomography (CT) is very effective in detecting and staging adenocarcinoma, with a sensitivity of up to 90% for detection and an accuracy of 80–90% for staging, but it has limitations in detecting small cancers. Moreover, it is not very accurate for determining nonresectability because small liver metastases, peritoneal carcinomatosis, and subtle signs of vascular infiltration may be missed. Multidetector-row CT (MDCT) has brought substantial improvements with its inherent ability to visualize vascular involvement in three dimensions. MDCT has been found to be at least equivalent to contrast-enhanced magnetic resonance imaging (MRI) for detecting adenocarcinoma. MRI can be used as a problem-solving tool in equivocal CT: MRI may help rule out pitfalls, such as inflammatory pseudotumor, focal lipomatosis, abscess, or cystic tumors. Mangafodipir-enhanced MRI reveals a very high tumor-pancreas contrast, which helps in diagnosing small cancers. Endosonography is, if available, also a very accurate tool for detecting small cancers, with a sensitivity of up to 98%. It is the technique of choice for image-guided biopsy if a histologic diagnosis is required for further therapy.     

脑血吸虫病的CT与MRI诊断对比研究

目的：研究脑血吸虫病的CT、MRI表现，并探讨两种检查方法对该病的诊断价值。方法：本组28例患者均同时行CT、MRI检查(平扫 增强)，分析该病的影像学征象并结合9例手术病理资料进行对比。结果：27例有不同程度的水肿；22例呈水肿伴不规则结节，增强后呈结节状、斑片状及融合成簇状强化；CT发现54个病灶．MRI发现75个病灶。结论：脑血吸虫病在CT及MRI增强扫描中都具有特异性表现，MRI信号更接近其病理改变；两种检查方法郜具有重要的临床价值，但MRI明显优于CT。     

Calcification of the alar ligament of the cervical spine: imaging findings and clinical course

Ligamentous calcification of the cervical spine has been reported in the yellow ligament, anterior and posterior longitudinal ligaments and interspinous ligament. Calcification in the upper cervical spine is rare, although some cases with calcification of the transverse ligament of the atlas have been reported. Two patients with calcification of the alar ligament with an unusual clinical presentation and course are described. Examination by tomography and computed tomography (CT) showed calcification of the alar ligament and the transverse ligament of the atlas. CT documented decreased calcification as symptoms resolved. There may be a role for CT in the search for calcifications in the upper cervical spine in patients presenting with neck pain and pharyngodynia if radiographs are normal. Received: 13 October 2000 Revision requested: 17 November 2000 Revision received: 18 December 2000 Accepted: 19 December 2000     

CT and MRI appearances of a thoracic chordoma

A case of a chordoma in the thoracic spine is presented. This is a very rare tumour in this location and should be considered in the differential diagnosis of any posterior mediastinal mass. The appearances on CT and MRI were similar to chordomas described in other locations. On T2-weighted images septae of low signal intensity radiated throughout the large high-signal mass. This feature may be of use in differentiating chordomas from other posterior mediastinal masses. Received 12 September 1997; Revision received 2 April 1998; Accepted 29 April 1998     

Mucoid degeneration of the anterior cruciate ligament mistaken for ligamentous tears

Objective. To describe the MR features of mucoid degeneration of the anterior cruciate ligament (ACL) in a series of patients with MRI findings that were mistaken for tears in the majority of cases but who were found to have an intact ligament at arthroscopy. We will suggest a pathologic entity corresponding to this finding and describe some characteristic features that can be used to identify this entity on MRI. Design. A retrospective analysis of 10 MRI examinations of the knee was performed after arthroscopic evaluation. Prearthroscopic MRI findings had been interpreted as a tear in six patients prospectively and in the remaining four the diagnosis of mucoid degeneration was suggested and ultimately proven. All patients had an intact ACL by preoperative clinical examination, examination under anesthesia, and at arthroscopy. Results. MRI examinations demonstrated an ill-defined ACL, greater in girth than the normal ligament and characterized by increased signal on all sequences. The high-signal ligament was oriented in the normal direction of the ACL. The overall appearance of the ligament was retrospectively described as like a celery stalk. Arthroscopy demonstrated mechanically intact ligaments with a normal to expanded external appearance. Probing of three of the ligaments caused a material to be expressed and pathologic evaluation resulted in the diagnosis of cystic, mucoid degeneration. Conclusion. Mucoid degeneration and an intact ACL can be suspected when an apparently thickened and ill-defined ligament with increased signal intensity on all sequences is identified in a patient with a clinically intact ligament. Received: 10 April 2000 Revision requested: 18 July 2000 Revision received: 13 November 2000 Accepted: 27 November 2000