[Noninvasive diagnosis of cerebral venous thrombosis]. 
Cerebral venous thrombosis (CVT) is an uncommon condition.  Its variable, unspecific clinical presentation causes delays in diagnosis.  We analyze the validity of different neuroimaging techniques, including CT, MRI, MR angiography, and conventional angiography in the diagnosis of CVT.  We review the imaging findings of 12 patients with the final diagnosis of CVT.  All 12 patients underwent CT as the initial imaging test; all 12 underwent MRI; 11 underwent MR angiography; and 4 underwent conventional angiography.  Visualization of the thrombus or filling defects in the affected vessel were considered direct signs of CVT, whereas findings compatible with venous infarction were considered indirect signs.  Of the 12 CT examinations, 4 showed direct signs, 2 indirect signs, and 6 only normal findings.  Indirect signs of CVT were seen on follow-up CT in three of the patients with normal initial CT examination.  CT failed to show the real extent of the process except in one case in which a cortical vein was affected.  MRI detected thrombi in the affected territory in 6 cases; the empty delta sign was seen in 2 and signs of venous infarction in 8.  MRI failed to diagnose CVT in one case.  MR angiography showed direct signs of CVT in all cases, even without intravenous contrast, and the results were similar to those seen at conventional angiography.  More than two locations were affected in 11 patients.  At CT, indirect signs of CVT are seen, although sometimes not immediately.  Direct signs can be so subtle that they can only be interpreted with experience.  Furthermore, CT does not show the real extent of the process.  Nevertheless, given its availability, contrast-enhanced CT should be the primary imaging test, both to rule out other possibilities and to indicate other neuroimaging studies, in this case MRI and MR angiography.  The results obtained when these two techniques are performed simultaneously, even without contrast administration, are sufficient for diagnosis and are comparable to those at conventional angiography, but without the risks entailed and without exposing the patient to ionizing radiation.