Spontaneous subarachnoid hemorrhage and negative initial vascular imaging--should further investigation depend upon the pattern of hemorrhage on the presenting CT?

BACKGROUND: Multiple investigations are usually performed in patients with spontaneous SAH who have negative initial angiography. This study aimed to evaluate the most appropriate use of additional imaging studies and how this may be influenced by the findings of the initial CT. METHODS: A retrospective analysis was performed on a prospectively collected cohort of patients referred with spontaneous SAH and negative initial angiography. The patients were divided into four categories based upon the distribution of blood on the initial CT: perimesencephalic (pSAH), diffuse (dSAH), sulcal (sSAH) and CT negative (CSF positive for xanthochromia) (nCT-pLP). The number and nature of the subsequent imaging investigations were reviewed, and the results were correlated with the findings of the presenting CT. RESULTS: One hundred fourteen patients were included in the study. Repeat imaging found five relevant abnormalities. Three cases of vasculitis were diagnosed on the first DSA following a negative CTA. A case of dissecting aneurysm was revealed on the third neurovascular study. A hemorrhagic spinal tumor presented with xanthochromia. No subsequent abnormality was found on the third DSA or MRI head. No case of pSAH had a subsequent positive finding if the initial CTA was negative. CONCLUSIONS: Certain patterns of SAH are associated with a low yield of abnormalities on repeat imaging if the initial angiography is normal. The authors believe that the pattern of hemorrhage on the presenting CT should be used to guide the most appropriate use of further imaging modalities and present a diagnostic algorithm for this purpose.

Symptomatic perianeurysmal edema following bare platinum embolization of a small unruptured cerebral aneurysm.

There is considerable interest in the development of symptomatic inflammatory reactions following coil embolization of cerebral aneurysms. Patients have experienced a range of adverse events, usually after treatment of moderately large aneurysms with modified "bioactive" coils. More recently, it has been recognized that adverse inflammatory reactions can be associated with the use of "nonbioactive" coils, and we present a case of symptomatic perianeurysmal edema after treatment of a small unruptured aneurysm with bare platinum coils.

The value of radio-anatomical features on non-contrast CT scans in localizing the source in aneurysmal subarachnoid haemorrhage.

Identification of the source of subarachnoid haemorrhage (SAH) can be a challenge in the presence of multiple aneurysms. This study was carried out to assess whether radioanatomical features on noncontrast enhanced computerised tomography (CT) scans may be of value in localizing ruptured intracranial aneurysms. The diagnostic CT scans of 56 consecutive patients, investigated for SAH with cerebral angiography, over a period of six months were available for review. Various radioanatomical features were assessed: (1) pattern of subarachnoid blood (e.g. predominant site and location near major vessel bifurcation), (2) presence of intraparenchymal haematoma, (3) presence of aneurysm contour and (4) hydrocephalus. On the basis of the findings an estimation of the anatomical location of the source of bleeding was made and then compared with the angiogram findings to which the reviewer was blinded. The location of the aneurysm was correctly identified in 89.5% of cases. Careful analysis of the pattern of bleeding was essential for the successful localization of the aneurysm in all these cases. The presence of an aneurysm contour was also associated with correct identification of the source of bleeding (chi(2) = 6.067, P = 0.02). Our findings suggest that radioanatomical features on CT scans in SAH can be a valuable aid in the correct identification of the location of the ruptured aneurysm. This would be of particular significance in the presence of multiple intracranial aneurysms.

Serial analysis of magnetization-transfer histograms and Expanded Disability Status Scale scores in patients with relapsing-remitting multiple sclerosis.

BACKGROUND AND PURPOSE: Magnetization transfer ratio histogram peak height (MTR-HPH) has been shown to correlate with macroscopic and microscopic brain disease in patients with multiple sclerosis (MS). We studied the changes in MTR-HPH and in Kurtzke's Expanded Disability Status Scale (EDSS) scores over time in a group of patients with relapsing-remitting MS. METHODS: Twenty adult patients with relapsing-remitting MS (four men and 16 women) were followed up for a period of 334 to 1313 days. In all, 86 MR imaging studies of the brain were obtained, and MTR-HPH was calculated for each MR examination by using a semiautomated technique. Changes in MTR-HPH were compared between patients over the study's duration. A neurologist specialized in the care of MS patients assessed the EDSS score for each patient as a measure of clinical disability. RESULTS: Serial MR data showed a subtle but significant decline in MTR-HPH with time. No significant changes in EDSS scores were noted over the same period. CONCLUSION: Patients with relapsing-remitting MS have a significant progressive decline in normalized MTR-HPH, which is independent of EDSS score. MTR-HPH measurements can be used to monitor subclinical disease in patients with relapsing-remitting MS over a short time frame of 1 to 4 years. This parameter might be applied in future therapeutic trials to assess its usefulness.

Benign extraovarian mimics of ovarian cancer. Distinction with imaging studies.

Imaging of the pelvis via computed tomography (CT), ultrasound, or magnetic resonance (MR) provides excellent anatomical detail and superb resolution. Despite this, radiologists often have difficulty reaching a specific diagnosis in evaluating adnexal masses. A wide spectrum of benign extraovarian pathology may closely resemble ovarian cancer. Fallopian tube disease such as hydrosalpinx, tuboovarian abscess, and chronic ectopic pregnancy may mimic cystic or solid ovarian neoplasm. Pedunculated uterine leiomyomas may imitate ovarian lesions. Gastrointestinal causes of adnexal masses include mucocele, abscess, and hematoma. These entities may appear similar to ovarian lesions, thus requiring close attention to specific anatomical detail in order to help differentiate them. Similarly, peritoneal disease including tuberculous peritonitis and peritoneal pseudocyst may simulate ovarian tumor. While ultrasound represents the initial imaging modality in the evaluation of most pelvic disease, MR's multiplanar capability and improved tissue characterization make it a valuable modality in many circumstances.

Preoperative MRI diagnosis of Lhermitte-Duclos disease: case report with associated enlarged vessel and syrinx.

BACKGROUND: The most common primary cerebellar tumor is hemangioblastoma, a lesion which is associated with magnetic resonance imaging (MR)-detectable vascularity in over 60%. Lhermitte-Duclos disease is an uncommon cause of a cerebellar mass that is not typically vascular. METHODS: Computed tomography (CT), MRI with and without contrast, and magnetic resonance venography was performed in a patient with a cerebellar mass. RESULTS: The cerebellar mass was noted to have a prominent vessel, as well as an associated syrinx. In spite of MRI-detectable vascularity, the striped appearance of the lesion was felt to be typical of Lhermitte-Duclos disease. At surgery, the mass was resected and the diagnosis of Lhermitte-Duclos disease was confirmed. CONCLUSIONS: The diagnosis of Lhermitte-Duclos disease should be made when MRI shows a parallel linear "tiger-striped" lesion of the cerebellum. The presence of an enlarged vessel and/or syrinx should not deter one from making the preoperative diagnosis.

Low attenuation of acute traumatic hemoperitoneum on CT scans.

OBJECTIVE: This study was undertaken to determine the incidence of low attenuation values in intraperitoneal hemorrhage, which could be confused with ascites. MATERIALS AND METHODS: We retrospectively analyzed the CT scans of 42 consecutive patients with hepatic and splenic lacerations and intraperitoneal fluid after blunt abdominal trauma. Patients were excluded if they had prior peritoneal lavage, bladder or bowel injury, or low hematocrit values. Intraperitoneal fluid was categorized by the site of accumulation (perihepatic, perisplenic, Morison's pouch, paracolic gutters, or pelvis). The amount of fluid in each intraperitoneal location was categorized as small, moderate, or large. Attenuation values were obtained from each intraperitoneal site, and overall mean attenuation values were determined for each patient. We correlated the size of each fluid collection with the attenuation value. We also compared attenuation values at locations adjacent to the site of each injury with those at other intraperitoneal sites. We then evaluated technical factors that could have lowered attenuation values, including CT miscalibration, volume averaging, and beam-hardening artifacts. RESULTS: For the 42 patients, we measured 131 separate attenuation values. Attenuation values ranged from 0 to 80 H, with attenuation of 24% of sites (32/131) measuring less than 20 H. Only 16% of sites (21/131) had attenuation values greater than 45 H. Attenuation at the remaining 78 sites (60%) measured from 20 to 45 H. All intraperitoneal locations except the pelvis had mean attenuation values significantly lower then 40 H. Mean attenuation values (determined by averaging measurements from different intraperitoneal sites) were also calculated for each patient. Only 6 (14%) of 42 patients had mean attenuation values greater than 40 H, whereas 4 (10%) of 42 patients had mean attenuation values less than 20 H. The remaining 32 patients (76%) had mean attenuation values between 21 and 40 H. Patients with hepatic lacerations showed no significant difference (p = .3509) in attenuation between perihepatic fluid and the remainder of intraperitoneal fluid. However, in patients with splenic lacerations, perisplenic fluid had a significantly higher (p = .0013) attenuation value (43 H) than did fluid at other intraperitoneal locations. CONCLUSION: Low attenuation measurements for acute hemoperitoneum represented a common finding that was not attributable to technical factors or underlying anemia. Fluid with attenuation values less than 20 H in acute trauma should not be dismissed as ascitic fluid.

CT in patients with blunt abdominal trauma: clinical significance of intraperitoneal fluid detected on a scan with otherwise normal findings.

OBJECTIVE: The purpose of this study was to determine the clinical significance of intraperitoneal fluid seen on CT scans with otherwise normal findings in patients with blunt abdominal trauma. MATERIALS AND METHODS: We retrospectively analyzed the CT scans of 60 patients with blunt abdominal trauma who had scans showing normal findings except for the presence of intraperitoneal fluid. The location of the fluid was determined (pouch of Douglas, pelvis, paracolic gutters, mesentery, Morison's pouch, perihepatic or perisplenic spaces). The amount of fluid in each location was categorized as minimal, moderate, or marked. The total volume of fluid in each patient was estimated as small (+1), intermediate (+2), or large (+3) on the basis of the sum of the amount of fluid in the individual peritoneal locations. The amount and location of fluid were compared between patients who required exploratory laparotomy and those who were managed conservatively. RESULTS: In most patients, the total fluid volume was small (44 patients, 73%) as opposed to intermediate (11 patients, 18%) or marked (five patients, 8%). Thirty-seven patients had fluid in one location, 12 patients had fluid in two locations, and 11 patients had fluid in three or more locations. Intraperitoneal fluid tended to accumulate in the pouch of Douglas (67%) and Morison's pouch (33%). Patients requiring laparotomy had a higher total fluid volume score compared with the patients managed conservatively (2.2 versus 1.3, p < .002) and had larger amounts of fluid in the upper abdomen. Laparotomy was required in only one patient (2%) who had a small amount of fluid compared with three patients (27%) with intermediate and two patients (40%) with marked amounts. Mesenteric and/or bowel injuries were noted in all six patients at laparotomy. One patient had a small superficial liver laceration that was not diagnosed with CT. No other injuries to the solid viscera were missed on the scans. Two of the four patients with mesenteric fluid seen on the CT scan had mesenteric lacerations found during surgery, and the remaining two did well with conservative management. CONCLUSION: Patients with blunt abdominal trauma who have small amounts of intraperitoneal fluid as the sole abnormality shown by CT may generally be treated conservatively. However, patients with even a small quantity of mesenteric fluid may benefit from peritoneal lavage to help exclude bowel or mesenteric injury. Intermediate and large amounts of fluid are less common as the sole CT abnormality but have a higher likelihood of being associated with bowel or mesenteric injury.