CT Angiography in Evaluating Large-Vessel Occlusion in Acute Anterior Circulation Ischemic Stroke: Factors Associated with Diagnostic Error in Clinical Practice.

BACKGROUND AND PURPOSE: It is currently not completely clear how well radiologists perform in evaluating large-vessel occlusion on CTA in acute ischemic stroke. The purpose of this study was to investigate potential factors associated with diagnostic error. MATERIALS AND METHODS: Five hundred twenty consecutive patients with a clinical diagnosis of acute ischemic stroke (49.4% men; mean age, 72 years) who underwent CTA to evaluate large-vessel occlusion of the proximal anterior circulation were included. CTA scans were retrospectively reviewed by a consensus panel of 2 neuroradiologists. Logistic regression analysis was performed to investigate the association between several variables and missed large-vessel occlusion at the initial CTA interpretation. RESULTS: The prevalence of large-vessel occlusion was 16% (84/520 patients); 20% (17/84) of large-vessel occlusions were missed at the initial CTA evaluation. In multivariate analysis, non-neuroradiologists were more likely to miss large-vessel occlusion compared with neuroradiologists (OR = 5.62; 95% CI, 1.06-29.85; P = .04), and occlusions of the M2 segment were more likely to be missed compared with occlusions of the distal internal carotid artery and/or M1 segment (OR = 5.69; 95% CI, 1.44-22.57; P = .01). There were no calcified emboli in initially correctly identified large-vessel occlusions. However, calcified emboli were present in 4 of 17 (24%) initially missed or misinterpreted large-vessel occlusions. CONCLUSIONS: Several factors may have an association with missing a large-vessel occlusion on CTA, including the CTA interpreter (non-neuroradiologists versus neuroradiologists), large-vessel occlusion location (M2 segment versus the distal internal carotid artery and/or M1 segment), and large-vessel occlusion caused by calcified emboli. Awareness of these factors may improve the accuracy in interpreting CTA and eventually improve stroke outcome.

Observer variation in the evaluation of lumbar herniated discs and root compression: spiral CT compared with MRI.

Spiral CT is considered the best alternative for MRI in the evaluation of herniated discs. The purpose of this study was to compare radiological evaluation of spiral CT with MRI in patients suspected of herniated discs. 57 patients with lumbosacral radicular syndrome underwent spiral CT and 1.5 T MRI. Two neuroradiologists independently evaluated 171 intervertebral discs for herniation or "bulge" and 456 nerve roots for root compression, once after CT and once after MRI. We compared interobserver agreement using the kappa statistic and we performed a paired comparison between CT and MRI. For detection of herniated or bulging discs, we observed no significant difference in interobserver agreement (CT kappa 0.66 vs MRI kappa 0.71; p = 0.40). For root compression, we observed significantly better interobserver agreement at MRI evaluation (CT kappa 0.59 vs MRI kappa 0.78; p = 0.01). In 30 of 171 lumbar discs (18%) and in 54 of 456 nerve roots (12%), the observers disagreed on whether CT results were similar to MRI. In the cases without disagreement, CT differed from MRI in 6 discs (3.5%) and in 3 nerve roots (0.7%). For radiological evaluation of lumbar herniated discs, we found no evidence that spiral CT is inferior to MRI. For evaluating lumbar nerve root compression, spiral CT is less reliable than MRI.

Symptomatic and asymptomatic abnormalities in patients with lumbosacral radicular syndrome: Clinical examination compared with MRI.

OBJECTIVE: To determine the frequency of symptomatic and asymptomatic herniated discs and root compression in patients with lumbosacral radicular syndrome (LRS) and to correlate clinical localization with MRI findings. METHODS: Fifty-seven patients with unilateral LRS were included in the study. Using the visual analogue scale, two physicians independently localized the most likely lumbar level of complaints. These clinical predictions of localizations were correlated with the MRI findings. RESULTS: MRI showed abnormalities on the symptomatic side in 42 of 57 patients (74%). In 30% of the patients, MRI confirmed an abnormality at the exact same level as determined after clinical examination. On the asymptomatic side, MRI showed abnormalities in 19 of 57 patients (33%), 13 (23%) of these patients had asymptomatic root compression. CONCLUSIONS: In more than two-thirds of the patients with unilateral LRS there was no exact match between the level predicted by clinical examination and MRI findings. These discrepancies complicate the decision whether or not to operate.

Quantitative assessment of dural ectasia as a marker for Marfan syndrome.

PURPOSE: To establish normal values for lumbosacral dural sac dimensions with magnetic resonance (MR) imaging and to use these values to assess the sensitivity and specificity of dural ectasia as a marker for Marfan syndrome. MATERIALS AND METHODS: MR imaging was performed to measure dural sac diameter (DSD) from L1 through S1 in 44 adult patients with Marfan syndrome and in 44 matched control subjects. DSD values were corrected for vertebral body size, yielding dural sac ratios (DSRs). The control subjects served to establish the upper limit of normal DSR values at the L1 through S1 levels. RESULTS: Cutoff values for normal DSRs for L1 through S1 were 0.64, 0.55, 0.47, 0.48, 0.48, and 0.57. Significant DSR differences were shown at all levels between patients with Marfan syndrome and control subjects (P <.001 at all levels). At L1 through S1, the sensitivity of dural ectasia as a marker for Marfan syndrome was 45%-77%, and the specificity was 95% or greater. By combining levels L3 and S1, dural ectasia as a marker for Marfan syndrome yielded a sensitivity of 95% (42 of 44 patients) and a specificity of 98% (43 of 44). The presence of dural ectasia excelled, compared with the presence of other Marfan syndrome manifestations in the patient population. CONCLUSION: Abnormal DSR values at L3 or S1 can be used to identify Marfan syndrome with 95% sensitivity and 98% specificity.

CT angiography of the circle of Willis and intracranial internal carotid arteries: maximum intensity projection with matched mask bone elimination-feasibility study.

Results are reported of a feasibility study in which bone pixels are eliminated from computed tomographic (CT) angiographic images with a method that enables the construction of maximum intensity projection (MIP) images without interference by bone. The method proved to be successful in six patients. Two observers blinded to the bone elimination method judged the image quality of MIP images to be considerably higher than that of standard subtraction MIP images. This method is an effective means to remove bone from CT angiographic images with only a slight increase in radiation dose.

MR angiography as a screening tool for intracranial aneurysms: feasibility, test characteristics, and interobserver agreement.

OBJECTIVE: MR angiography may be an appropriate tool to screen for unruptured intracranial aneurysms. Feasibility, test characteristics, and interobserver agreement in evaluation of MR angiograms were assessed by members of the MARS (Magnetic resonance Angiography in Relatives of patients with Subarachnoid hemorrhage) Study Group. SUBJECTS AND METHODS: We screened 626 first-degree relatives of a consecutive series of 193 patients with subarachnoid hemorrhage examined at two institutions. We used MR imaging and MR angiography (three-dimensional time-of-flight imaging at both institutions and additional three-dimensional phase-contrast imaging at one institution). Three observers independently assessed the MR angiograms. Conventional angiography was performed in relatives with possible or definite aneurysms on MR angiography and was considered the standard of reference. RESULTS: Thirty-three aneurysms were found in 25 (4%; 95% confidence interval [CI], 3-6%) of 626 relatives. Thirteen (8%) of 169 relatives who refused screening had MR-related reasons; an additional six persons could not be screened because of contraindications for MR imaging (pregnancy, n = 1; claustrophobia, n = 5). The positive predictive value of MR angiography was 100% (95% CI, 79-100%) for "definite" aneurysms and 58% (95% CI, 28-85%) for "possible" aneurysms. Sensitivity of MR angiography was estimated at 83% (95% CI, 65-94%) and specificity at 97% (95% CI, 94-98%). Interobserver agreement in the evaluation of MR angiograms was poor (kappa < .30), probably because different diagnostic strategies used by individual observers resulted in different use of the assessment category "possible aneurysm." CONCLUSION: MR angiography is a feasible screening tool for detection of intracranial aneurysms. Positive predictive value, sensitivity, and specificity are acceptable when at least two neuroradiologists independently assess MR angiograms.

Petrosal bone: coronal reconstructions from axial spiral CT data obtained with 0.5-mm collimation can replace direct coronal sequential CT scans.

PURPOSE: To investigate whether coronal multiplanar reconstruction (MPR) images of the petrosal bone from axial spiral computed tomographic (CT) data obtained with 0.5-mm collimation can replace direct coronal sequential CT scans obtained with 0.5- or 1.0-mm collimation. MATERIALS AND METHODS: The differences in diagnostic quality between thin-section coronal sequential CT scans of 24 petrosal bones in 12 patients and matched MPR images were assessed by five observers. The matched MPR images were calculated with both trilinear and tricubic interpolation. Image resolution was determined by measuring the three-dimensional point spread function. RESULTS: All observers preferred tricubically interpolated MPR images over trilinearly interpolated images. Subjective differences in image quality between direct coronal scans and matched tricubically interpolated MPR images were small. Only the direct coronal scans with the highest image quality (0.5-mm collimation, 465 mAs) were judged to be slightly better than the matched MPR images. With regard to direct coronal scans obtained at 245 mAs and/or 1.0-mm collimation, either there was no preference or the MPR images were preferred. CONCLUSION: Coronal MPR images from axial spiral CT obtained with 0.5-mm collimation can replace direct coronal sequential CT scans.

Correlation between electromyographic reflex and MR imaging examinations of the trigeminal nerve.

BACKGROUND AND PURPOSE: Previous studies have shown that clinical localization of trigeminal nerve lesions is inaccurate as compared with MR imaging findings. The purpose of our study was to ascertain the added value of electromyographic (EMG) investigation of the trigeminal nerve reflexes for the improvement of lesion localization and for the preselection of patients for MR imaging. METHODS: We reviewed the EMG studies of the trigeminal reflexes and the MR imaging studies of 20 patients with unilateral symptoms and signs related to the trigeminal nerve (40 trigeminal nerves examined). The results of the two studies were compared to assess the value of EMG in predicting MR imaging outcome. Lesion localization as demonstrated by EMG was compared with localization at MR imaging. MR imaging was used as the standard of reference. RESULTS: Eight (40%) of 20 patients had MR imaging findings related to presenting trigeminal symptoms, including five brain stem lesions and three peripheral lesions. Fourteen (70%) of 20 patients had EMG abnormalities related to presenting symptoms and signs. For brain stem lesions, lesion localization as shown by EMG corresponded well with MR imaging findings. EMG yielded a sensitivity of 100%, a specificity of 81%, a positive predictive value of 57%, and a negative predictive value of 100% in predicting MR imaging results. Interobserver agreement was good for both the EMG reflex and MR imaging examinations. CONCLUSION: Our data suggest that EMG recordings of the trigeminal reflexes can be used to exclude structural lesions in patients with symptoms related to the trigeminal nerve. When a lesion is localized in the brain stem with EMG, a tailored MR imaging examination of this region may be sufficient.

Primary nerve-sheath tumours of the trigeminal nerve: clinical and MRI findings.

We reviewed the clinical and MRI findings in primary nerve-sheath tumours of the trigeminal nerve. We retrospectively reviewed the medical records, imaging and histological specimens of 10 patients with 11 primary tumours of the trigeminal nerve. We assessed whether tumour site, size, morphology or signal characteristics were related to symptoms and signs or histological findings. Histological proof was available for 8 of 11 tumours: six schwannomas and two plexiform neurofibromas. The other three tumours were thought to be schwannomas, because they were present in patients with neurofibromatosis type 2 and followed the course of the trigeminal nerve. Uncommon MRI appearances were observed in three schwannomas and included a large intratumoral haemorrhage, a mainly low-signal appearance on T2-weighted images and a rim-enhancing, multicystic appearance. Only four of nine schwannomas caused trigeminal nerve symptoms, including two with large cystic components, one haemorrhagic and one solid tumor. Of the five schwannomas which did not cause any trigeminal nerve symptoms, two were large. Only one of the plexiform neurofibromas caused trigeminal nerve symptoms. Additional neurological symptoms and signs, not related to the trigeminal nerve, could be attributed to the location of the tumour in three patients.

Symptoms and signs related to the trigeminal nerve: diagnostic yield of MR imaging.

PURPOSE: To assess the diagnostic yield of magnetic resonance (MR) imaging in patients with symptoms and signs related to the trigeminal nerve. MATERIALS AND METHODS: Medical records and MR imaging studies in 112 consecutive patients referred for MR imaging over 5 years were evaluated. MR images were independently reviewed by two neuroradiologists unaware of the clinical findings. Signs and symptoms at presentation were associated with either a positive or negative MR imaging outcome. Logistic regression analysis was performed to identify clinical variables related to imaging results. RESULTS: Sixty-eight (61%) patients had positive MR imaging findings related to symptoms and signs. Trigeminal neuralgia was correlated with a negative MR imaging outcome (P < .001). Numbness (P < .01), impaired sensation (P < .001), other neurologic symptoms and signs (P < .01), progression of symptoms and signs (P < .001), and duration of symptoms of less than 1 year (P < .001) corresponded to a positive MR imaging outcome. Two regression models, each with three clinical parameters (progression, duration < 1 year, and trigeminal neuralgia or impaired sensation), had comparable accuracy for prediction of the MR imaging outcome. CONCLUSION: Clinical findings can be used to identify groups in which a high or a low yield of MR imaging is correlated with symptoms and signs related to the trigeminal nerve.

Laparoscopic ultrasonography of abdominal lymph nodes: correlation with pathologic findings.

The value of laparoscopic ultrasonographic criteria for distinguishing benign from malignant lymph nodes was assessed. The following criteria were evaluated in 41 lymph nodes: (1) long axis diameter, (2) short axis diameter, (3) long axis-short axis ratio, (4) nodal border delineation, (5) presence of hyperechoic hilar reflection, (6) echogenicity, and (7) inhomogeneity. Pathologic examination showed malignant infiltration in 11 lymph nodes and the absence of malignant infiltration in 30 lymph nodes. The presence of a hyperechoic center or a long axis-short axis ratio more than 2 suggested the absence of malignant infiltration, whereas inhomogeneity was suggestive of malignant infiltration. The other criteria did not seem useful in distinguishing benign from malignant lymph nodes.

Trigeminal neuralgia: comparison of two MR imaging techniques in the demonstration of neurovascular contact.

PURPOSE: To compare two magnetic resonance (MR) imaging techniques for demonstration of vascular contact with the trigeminal nerve. MATERIALS AND METHODS: Thirteen patients with unilateral trigeminal neuralgia and 50 control subjects underwent three-dimensional fast inflow with steady-state precession (FISP) and contrast material-enhanced magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) MR imaging. The images were independently reviewed by two neuroradiologists, who were blinded to the clinical details. Six of the 13 patients underwent surgery. RESULTS: Vascular contact with the trigeminal nerve at the root entry zone was seen on FISP images in 10 of 13 (77%) symptomatic nerves and in eight of 113 (7%) asymptomatic nerves (P < .001). MP-RAGE and FISP images demonstrated arterial contacts equally well. MP-RAGE images demonstrated one additional venous contact at the root entry zone in a patient with ipsilateral trigeminal neuralgia. Interobserver agreement was good for both FISP (kappa = 0.69) and MP-RAGE (kappa = 0.78) images. The presence of vascular contact at the root entry zone, seen on preoperative MR images, was confirmed in all six patients who underwent surgery. CONCLUSION: Both FISP and MP-RAGE MR imaging are useful in demonstrating vascular contact with the trigeminal nerve at the root entry zone in patients with trigeminal neuralgia.

Perineural tumor extension along the trigeminal nerve: magnetic resonance imaging findings.

OBJECTIVE: To evaluate the magnetic resonance imaging (MRI) findings of 15 patients with perineural tumor extension along the trigeminal nerve in correlation with clinical data. METHODS: The clinical records and MRI studies of 15 patients with perineural tumor extension along the trigeminal nerve were retrospectively reviewed. Imaging studies included plain and contrast-enhanced thin section T1-weighted spin echo (T1-WSE) MRI with and without fat-suppression. The studies were compared to determine which sequence provided greatest tumor conspicuity and best depiction of tumor extent. The conspicuity of these tumors was assessed on the available sequences by two observers by consensus. RESULTS: The contrast-enhanced T1-weighted spin echo fat-suppressed images (T1-WSECEFS) demonstrated greatest tumor conspicuity and best depiction of tumor extent in the extracranial head and neck and skull base region. The conventional T1-weighted spin echo pre- and postcontrast images were, however, diagnostic of perineural tumor extension in 11 patients due to the presence of considerable tumor bulk and extension well above the skull base. In the other four patients the perineural tumor was poorly visualized on the conventional T1-WSE images and well visualized on the fat-suppressed images. The mandibular division of the trigeminal nerve (V3) was most commonly involved (n = 10), followed by the maxillary (V2; n = 5) and ophthalmic (V1; n = 2) division. Two patients had both mandibular as well as maxillary nerve involvement. The finding of perineural tumor extension had significant impact on patient management: based on the MR imaging study, the primary tumor was considered inoperable (n = 13), the extent of surgery was expanded (n = 2) and radiation therapy (RT) ports were extended (n = 12). CONCLUSION: Complete trigeminal nerve imaging is recommended when evaluating (suspected) head and neck malignancies with a high risk for perineural extension. In these cases thin section axial and coronal precontrast T1-WSE MR images and postcontrast T1-WSE MR images with fat-suppression should be obtained. In the rare event that artifacts degrade the quality of the fat-suppressed images, contrast-enhanced T1-WSE sequences without fat-suppression can additionally be used.

Melanosis naeviformis of Becker and scoliosis: a coincidence?

Melanosis naeviformis of Becker (MNB) can be associated with hypoplasia of soft tissue or extremities, spina bifida and scoliosis of the vertebral column. We have investigated 50 patients (42 men, 8 women) with MNB radiologically. Scoliosis was diagnosed in 13 patients (26%). The curves of scoliosis varied from 11 degrees to 17 degrees. Physical examination revealed no gross asymmetries of the trunk, extremities or breasts. No correlation was seen between the age of patients and the scoliotic curve. In one family the father and oldest son had MNB with scoliosis and the other son and daughter had MNB without scoliosis. Since only mild scoliosis is found in patients with MNB, X-ray examination of the vertebral column has no therapeutic consequences.

Review of artifacts associated with transrectal ultrasound: understanding, recognition, and prevention of misinterpretation.

Artifacts are inadequate representations of the structures being imaged. Transrectal ultrasound (TRUS) used for evaluating rectal tumors has its own, unique spectrum of artifacts such as (1) pseudomasses (beam thickness: imaging of rectal folds; mirror image: reflection at an intraluminal fluid level); (2) inadequate size of the lesion (mirror image or grating lobes); (3) simulation of malignant infiltration (beam thickness, attenuation or refraction); (4) incomplete field of view (shadowing; reverberation or mirror-image); (5) confusing echo patterns (side lobe artifacts or mirror image: reflection at the balloon surface). The understanding of the physical properties of ultrasound is the basis for the recognition of these artifacts and prevention of misinterpretation. We present a review of these artifacts and their causes.

Assessment of tumor infiltration depth in rectal cancer with transrectal sonography: caution is necessary.

PURPOSE: To assess the depth of infiltration of rectal cancer with transrectal ultrasound (US) (TRUS) and analyze interpretation errors. MATERIALS AND METHODS: Fifty-five consecutive patients with rectal cancer who underwent TRUS were prospectively studied. The effect of different patient inclusion criteria and US criteria was evaluated retrospectively. RESULTS: Extensive overstaging of T2 tumors, partially caused by inflammatory (desmoplastic) reaction or retraction of the muscularis propria, resulted in a specificity of only 24% for detection of perirectal infiltration. Sensitivity was 97%, and accuracy was 64%. Considerable variation in staging accuracy was observed when different patient selection criteria were used. Variation of US criteria improved differentiation between T2 and T3 tumors only slightly. CONCLUSION: The effect of different US criteria on differentiation of T2 and T3 tumors is limited. Spontaneous or iatrogenic inflammation is a major limiting factor. The accuracy of TRUS in staging rectal cancer is affected by patient inclusion criteria.

Perineural tumor extension of facial malignant melanoma: CT and MRI.

A case of retrograde perineural tumor that spread from malignant melanoma of the face is reported. Contrast-enhanced CT and plain and contrast-enhanced MR studies, including fat suppression technique, showed tumor extension along the maxillary division of the trigeminal nerve. Histopathological examination of the surgical specimen revealed neurotropic malignant melanoma and confirmed the extent of tumor spread in the perineurium.

Colorectal adenomas: inflammatory changes that simulate malignancy after laser coagulation--evaluation with transrectal US.

To evaluate the assumption that inflammatory changes in the rectal wall after treatment of colorectal adenoma with photocoagulation may simulate malignant infiltration, the findings were reviewed in 23 follow-up examinations performed with transrectal ultrasound (TRUS) in 17 patients with benign adenoma. Special attention was given to the appearance of the wall layers underneath the adenoma. After partial coagulation, changes in the colorectal wall were usually seen on TRUS scans obtained early in follow-up; sometimes the thickened muscle layer had an irregular outer margin. In three of the 13 early examinations, lesions mimicked malignancy. To correlate these findings with histologic proof, an experimental study was performed: Colorectal specimens from pigs were examined with ultrasound (US) and microscopy. The abnormal sonographic appearance of specimens on US scans was caused by an inflammatory reaction in the deep wall layers; concomitant serositis appeared to be responsible for the malignancy-mimicking irregular outer margin. In screening for malignancy in colorectal adenoma, TRUS may cause overstaging during the first 6 weeks after polypectomy or after a session of laser treatment and should be avoided.

Transrectal US in the diagnosis of localized colitis cystica profunda.

Colitis cystica profunda (CCP) mimicks rectal carcinoma, which makes distinguishing this benign lesion from the more common rectal neoplasm clinically and pathologically difficult. When transrectal ultrasound (US) was used in this case, three features of CCP were seen. There were multiple lesions, which did not penetrate beyond the submucosa. A large cystic component was seen, with a layer of uniform thickness in two of the three lesions. Non-solid contents and a lack of infiltration can be visualized at transrectal US, which helps diagnose CCP.