Case records of the Massachusetts General Hospital. Case 39-2006. A 24-year-old woman with systemic lupus erythematosus, seizures, and right arm weakness.
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Acanthamoeba↗
Biomedical subjects
Mark E Mullins
Publications and source records attributed to Mark E Mullins.
MR spectroscopy: truly molecular imaging; past, present and future.
MR spectroscopy involves the examination of molecules in a much more transparent manner than does routine, clinical, conventional MR imaging. Its performance and interpretation goes back to the origins of MR imaging in nuclear magnetic resonance and also points to a future in which functional type techniques such as molecular imaging tell more than simple anatomy, but also the physiology of what is seen when looking at a patient's radiological images. A brief discussion of the past, present, and appreciation of MR spectroscopy as a molecular imaging modality. Several techniques, applications, and controversies aso are discussed in this article.
Brain Chemistry↗
Modern emergent stroke imaging: pearls, protocols, and pitfalls.
Stroke remains one of the most important clinical diagnoses for which patients are referred to the radiologist for emergent imaging. Timely and accurate imaging guides admission from the emergency department or transfer to a hospital with a dedicated stroke service, triage to the intensive care unit, anticoagulation, thrombolysis, and many other forms of treatment and management. It is important to approach each patient's imaging needs logically and tailor each work-up, and constantly to review the entire process for potential improvements. Time saved in getting an accurate diagnosis of stroke may indeed decrease morbidity and mortality. This article discusses the current management of stroke imaging and reviews the relevant literature.
Acute Disease↗
Computed tomography follow-up imaging of stroke.
Due to its widespread availability, computer tomography (CT) scanning continues to be the primary initial imaging modality for assessment of patients with suspected acute stroke. It serves as a screening tool for other structural lesions which can mimic stroke and evaluates for possible hemorrhage prior to potential thrombolytic therapy. Findings seen on the initial CT may also serve as prognostic indicators of patient outcome helping with management decisions. As well, follow-up imaging in the subacute stages of infarct is also valuable for assessment of potential complications such as infarct extension, hemorrhagic transformation (and/or intracranial hemorrhage), and cerebral edema.
Brain Edema↗
Stroke imaging with xenon-CT.
This article briefly reviews the current literature and implementation of a typically non-firstline methodology to diagnose acute stroke: inhalational-mediated Xenon CT perfusion (Xe-CT). The intent of this article is to provide a short overview of this techniques; the reader is directed to the references for additional information.
Contrast Media↗
Rheumatoid meningitis: radiologic and pathologic correlation.
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Arthritis, Rheumatoid↗
Impact of PACS and voice-recognition reporting on the education of radiology residents.
RATIONALE AND OBJECTIVES: The introduction of picture archiving and communication system (PACS) has decreased the time needed to interpret radiology examinations resulting in an increased workflow. Because of concerns that the increase in exam throughput and the use of voice recognition may have a negative impact upon radiology resident education, a survey was conducted to assess the impact of PACS and voice recognition. MATERIALS AND METHODS: Residents at four diagnostic radiology training programs were surveyed. Survey topics included resident demographics, didactic and technical issues, and areas for improvement. RESULTS: One hundred thirty-four residents were polled with 42 respondents (42/134, 31.3%). The majority have been using PACS for more than 1 year (29/41, 70.7%) to interpret 75-100% of cases (33/39, 84.6%). A majority believed PACS is a superior teaching tool to printed film (28/38, 73.7%). However, only a minority (9/40, 22.5%) indicated that PACS was always used to contain teaching files and to conduct departmental conferences (5/40, 12.5%). The majority of respondents believed PACS have decreased the time needed to interpret diagnostic examinations (33/41, 80.5%). A majority (80.6%, 25/31) indicated that voice recognition takes more time than the traditional dictation and transcription process, where 51.3% (20/39, 51.3%) felt that voice recognition works well less than 50% of the time. CONCLUSIONS: Residents believe that PACS has positively affected their learning experience but indicate that it can be better utilized for resident education. Residents believe that voice recognition is less reliable and more time consuming than the traditional dictation system.
Adult↗
Imaging of incidental Bochdalek hernia.
Incidental adult Bochdalek hernia is a posterolateral diaphragmatic opening with transit of intra-abdominal contents into the thorax, having been diagnosed while being imaged for another reason. Size and contents are variable. Epidemiological factors and prevalence are controversial. Patients may suffer morbidity and mortality depending on involvement of organs. Diagnosis is made predominantly by routine computed tomographic scan, which is improved by the use of three-dimensional techniques and now-routine multi-detector row technology.
Aged↗
The hyperdense cerebral artery sign on head CT scan.
The hyperdense artery sign on noncontrast head CT is thought to be one of the earliest and most useful signs of intra-arterial clot and probable (clinical) stroke. It should be evaluated in the context of the clinical scenario. Rigorous criteria should be applied in order to reduce potential false positives. The hyperdense middle cerebral artery sign is the most studied version and correlates with patient outcome. Our data suggest that the density on noncontrast head CT is not likely to universally represent in situ clot.
Cerebral Arteries↗
Postoperative imaging of the pituitary gland.
Imaging often plays an important role in the management of patients who have been surgically treated for pituitary disease. The primary goals of the radiologist are to recognize normal postoperative findings, to distinguish iatrogenic changes in the sella and surrounding regions from residual tumor, and to detect surgical or therapy-related complications when apparent on imaging. Accurate assessment of the postoperative pituitary region requires an understanding of the normal sellar anatomy and of the common neurosurgical techniques applied to this region and familiarity with the appearance of this region in both the acute postoperative setting and also upon subsequent subacute and later examinations.
Humans↗
Radiation necrosis versus glioma recurrence: conventional MR imaging clues to diagnosis.
BACKGROUND AND PURPOSE: Conventional MR imaging findings are considered to be inadequate for reliably distinguishing radiation necrosis from tumor recurrence in patients with glioma. Despite this belief, we hypothesized that certain conventional MR imaging findings, alone or in combination, though not definitive, may favor one or another of these diagnoses in proton beam-treated patients with new enhancing lesions on serial scanning. METHODS: MR imaging findings (axial T1-, T2-, and post-gadolinium T1-weighted) of 27 proton beam radiation therapy patients with high-grade gliomas were retrospectively reviewed. Entry criteria included new MR imaging enhancing lesions after treatment and histologically unequivocal biopsy proof of diagnosis. Readers rated corpus callosum involvement, midline spread, subependymal spread, new discrete multiple enhancing foci, a "spreading wavefront" appearance, and septum pellucidum involvement. Statistical analysis was by the Fisher exact test. RESULTS: Corpus callosum involvement in combination with multiple other findings was highly associated with progressive glioma. These combinations included involvement of the corpus callosum with multiple enhancing foci (P = .02), involvement of the corpus callosum with crossing the midline and multiple enhancing lesions (P = .04), and involvement of the corpus callosum with subependymal spread and multiple enhancing lesions (P = .01). CONCLUSIONS: In proton beam-treated patients with glioma, corpus callosum involvement, in conjunction with multiple enhancing lesions with or without crossing of the midline and subependymal spread, favors predominant glioma progression. Overall, combinations of enhancement patterns were more likely than individual patterns to distinguish necrosis from predominant tumor progression. Together with clinical and functional imaging findings, these results may assist in determining the need for biopsy.
Aged↗
Intracranial hemorrhage complicating acute stroke: how common is hemorrhagic stroke on initial head CT scan and how often is initial clinical diagnosis of acute stroke eventually confirmed?
BACKGROUND AND PURPOSE: Assessment of possible hemorrhage in acute stroke before appropriate therapy remains important. The aim of this study was to determine the frequency with which patients present with clinical stroke and have intracranial hemorrhage on initial noncontrast head CT scan (NCCT). In addition, we sought to determine the frequency with which initial clinical diagnosis acute stroke is confirmed in this group. METHODS: Medical records of 691 consecutive patients with admitting diagnosis of acute stroke were evaluated retrospectively. Results of initial NCCT performed within 24 hours after presentation were assessed. All patients were examined before anticoagulation or thrombolysis. Correlation with treatment and leading differential etiology was made. RESULTS: Twenty-five patients (25/691 [3.6%]) had hemorrhage. Twenty-three patients (23/25 [92%]) had intraparenchymal hemorrhage only. One patient (1/25 [4%]) had a combination of intraparenchymal and subarachnoid hemorrhage. One patient (1/25 [4%]) had subdural hemorrhage only. Twenty-two NCCT scans (22/25 [88%]) were performed within 6 hours of presentation. Seventeen NCCT scans (17/25 [68%]) were performed within 3 hours of presentation. CONCLUSION: Despite frequent concerns for intracranial hemorrhage complicating acute stroke and treatment, a low percentage of patients had this complication. Moreover, our frequency is much lower than the wide ranges reported elsewhere. The most common type of intracranial hemorrhage in this cohort was intraparenchymal, but subarachnoid and subdural hemorrhages were also diagnosed and must also be considered. Twenty-eight percent of patients with initial suspicion of acute ischemic stroke are eventually given other diagnoses. These results may have implications for use of CT imaging.
Adult↗
Comparison of image quality between conventional and low-dose nonenhanced head CT.
BACKGROUND AND PURPOSE: Increasing use of CT for evaluating neurologic disease may expose patients to considerable levels of ionizing radiation. We compared the image quality of low-mAs head CT scans with that of conventional nonenhanced scans. METHODS: Conventional head CT scans were obtained in 20 patients (all >65 years with history of non-CNS malignancy) by using a multidetector technique: 170 mA and 1-second scanning time (ie, 170 mAs), 140 kVp, table speed of 7.5 mm per rotation, pitch of 0.75, section thickness of 5 mm, and field of view of 25 mm. A limited volume helical data acquisition covering four 5-mm-thick images was obtained by using 90 mAs but otherwise the same parameters. Three neuroradiologists visually rated the resulting images for quality in a blinded comparison. Representative 1- to 4-mm(2) regions of interest were chosen in gray matter and white matter locations. Conspicuity and the contrast-to-noise ratio were analyzed. Statistical comparisons were done by using the Student t test. RESULTS: Mean gray matter conspicuity was not significantly different between the 170- and 90-mAs groups (0.39 +/- 0.19 vs 0.41 +/- 0.03, P =.32). Mean gray matter contrast-to-noise ratio was approximately 22% higher with 170 mAs than with 90 mAs (1.77 +/- 0.52 vs 1.39 +/- 0.38, P =.005). All 90-mAs images were rated as having slightly greater image noise than the 170-mAs scans but with sufficient perceived resolution. CONCLUSION: Although 90-mAs head CT images were moderately noisier than 170-mAs images, they were rated as having acceptable diagnostic quality.
Aged↗
Review of suspected acute appendicitis in adults and children using CT and colonic contrast material.
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Acute Disease↗
The diagnosis of acute appendicitis in a pediatric population: to CT or not to CT.
PURPOSE: The aim of this study was to determine if focused appendiceal computed tomography with colon contrast (FACT-CC) increases the accuracy of the preoperative diagnosis of acute appendicitis in children. METHODS: A 5-year retrospective review was conducted of a university hospital database of 283 patients (age 0.8 to 19.3 years; mean, 11.3 years) treated with appendectomy for presumed acute appendicitis. RESULTS: Of the 283 patients in whom appendectomies were performed, 268 were confirmed by pathologic analysis of the specimen to have acute appendicitis for a diagnostic accuracy in our institution of 94.7%. Ninety-six patients (34%) underwent FACT-CC scans as part of their preoperative evaluation. The sensitivity of the computed tomography (CT) scan was 94.6%, and the positive predictive value was 95.6%. In girls older than 10 years, CT imaging was not significantly more accurate in predicting appendicitis than examination alone (93.9% v. 87.5%; P =.46). CONCLUSIONS: Preoperative FACT-CC did not increase the accuracy in diagnosing appendicitis when compared with patients diagnosed by history, physical examination and laboratory studies. If there was a strong suspicion of appendicitis, a negative CT scan did not exclude the diagnosis of appendicitis. However, focused appendiceal CT scan is a sensitive test with a high positive predictive value and may be useful in a patient with an atypical history or examination.
Acute Disease↗
Projected digital radiologic images for teaching: balance of image quality with data size constraints.
RATIONALE AND OBJECTIVES: The authors performed this study to determine, in the context of a teaching presentation with slides, the information content needed in a digitized radiologic image for it to be equivalent in quality to an analog image. MATERIALS AND METHODS: Eleven sets of radiologic images were obtained from a teaching file collection and digitized. The images were scanned at high resolution and saved as image files. The information content of each image was then halved repeatedly with repeat sampling of the image. This procedure was repeated nine times to yield a total of 10 images with an information content that ranged from very low (32 kB) to high (12 MB). Each of these image files was made into a 35-mm slide by using a digital slide maker. The original radiographs were subsequently made into slides by using conventional photographic methods. Care was taken to make the images identical in every respect except digitization and information content. The slides were shown to radiologists, who filled out questionnaires to rate image quality. RESULTS: Digitized slides that contain an average of 416 kB of data (the equivalent of a 750 x 570-pixel matrix with 8-bit gray levels) were equivalent to analog images for 90% of viewers. At 830 kB (1,060 x 800-pixel matrix with 8-bit gray levels), 100% of viewers found no difference between digitized and analog images. CONCLUSION: Digital images become indistinguishable from analog images if a sufficient amount of information is retained in the digital image. There is a defined relationship between the perception of quality and the information content of a digital image.
Image Processing, Computer-Assisted↗
CT and conventional and diffusion-weighted MR imaging in acute stroke: study in 691 patients at presentation to the emergency department.
PURPOSE: To compare the diagnostic accuracy of computed tomography (CT) and magnetic resonance (MR) imaging in a consecutive series of patients at presentation to the emergency department with symptoms of acute stroke. MATERIALS AND METHODS: Clinical data and images obtained in 691 consecutive patients with suspected acute stroke were examined. Results of first and second head CT and brain diffusion-weighted (DW) and conventional MR imaging were compared with each other and with the final neurologic discharge diagnosis. RESULTS: Five hundred seventy-three patients underwent CT at presentation, with 42% sensitivity (95% CI: 37%, 46%) and 91% specificity (95% CI: 82%, 96%). A total of 173 patients underwent a second CT examination, with 77% sensitivity (95% CI: 70%, 84%) and 79% specificity (95% CI: 49%, 95%). Of 498 MR images, 411 were DW, with 94% sensitivity (95% CI: 1%, 96%) and 97% specificity (95% CI: 88%, 100%), and 87 were conventional, with 70% sensitivity (95% CI: 58%, 81%) and 94% specificity (95% CI: 70%, 100%). By using DW MR imaging in the early period (<6 hours after presentation to emergency department), a 97% sensitivity (95% CI: 92%, 100%) and a 100% specificity (95% CI: 69%, 100%) were achieved, compared with 58% (29%-84%) and 100% (16%-100%), respectively, with conventional MR imaging, and 40% (35%-45%) and 92% (84%-97%), respectively, with CT. Negative predictive value was higher with DW MR imaging (73%) than with conventional (42%) MR imaging or CT (24%). In studies conducted within 12 hours, DW MR imaging achieved substantially superior accuracy than did CT. After 12 hours, accuracy was equivalent. CONCLUSION: In the diagnosis of stroke in the early period (<12 hours after presentation), DW MR imaging is superior to conventional MR imaging and CT.
Acute Disease↗
Influence of availability of clinical history on detection of early stroke using unenhanced CT and diffusion-weighted MR imaging.
OBJECTIVE: The radiologic diagnosis of stroke requires accurate detection and appropriate interpretation of relevant imaging findings; both detection and interpretation may be influenced by knowledge of the patient's presentation. In our study, we evaluated the effect of the availability of clinical history on the sensitivity for stroke detection using unenhanced CT and diffusion-weighted MR imaging. MATERIALS AND METHODS: The records of 733 consecutive patients with a clinically based admission diagnosis of early stroke were reviewed. Among the criteria for inclusion in our study were the availability of an unenhanced CT scan (561 cases) or diffusion-weighted MR imaging examination (409 cases) obtained at admission and a discharge diagnosis indicating whether a patient had actually had a stroke. The radiology requisition forms, available at the time of image interpretation, were classified as either indicating or not indicating a clinical suspicion of early stroke. Sensitivity, specificity, and accuracy of stroke detection were computed, stratified by the presence or absence of an available history indicating suspicion of stroke. Results were compared using the Fisher's exact two-tailed test. RESULTS: Unenhanced CT sensitivity was 52% (specificity, 95%) for the suspicion-of-stroke group and 38% (specificity, 89%) for the no-suspicion-of-stroke group (p = 0.008). Diffusion-weighted MR imaging sensitivity was 95% (specificity, 94%) for the suspicion-of-stroke group and 94% (specificity, 98%) for the no-suspicion-of-stroke group (p = 0.822). CONCLUSION: Availability of a clinical history indicating that early stroke is suspected significantly improves the sensitivity for detecting strokes on unenhanced CT without reducing specificity. In contradistinction, the availability of such a history did not significantly improve the sensitivity for detecting stroke using diffusion-weighted MR imaging. Whenever possible, relevant clinical history should be made available to physicians interpreting emergency CT scans of the head.
Aged↗