R. Felix

Percutaneous MRI-guided laser-induced thermotherapy for hepatic metastases for colorectal cancer

procedure. LITT was done after agreement from the local ethics committee and with the patients’ informed consent. All patients tolerated the procedure well; six had mild nausea and a symptomless right subphrenic haemorrhage developed in one. No deaths, infections, or liver or bile-duct injury occurred. During follow-up, 23 of 99 treated patients died: one of myocardial infarction, one from a stroke, 13 from tumour progression in the liver, and eight from tumour progression in other locations. The cumulative survival rate was 0·88 after 12 months, 0·70 after 24 months, and 0·42 after 36 months. Median survival time, calculated by the Kaplan-Meier method, was 36·4 months (figure). In patients with liver metastases of colorectal cancer, local tumour destruction with LITT under local anaesthesia is well tolerated and results in improved clinical outcome and survival. Our data can be a basis for a randomised comparison of LITT versus surgery.

“Menigeal sign”: a characteristic finding of meningiomas on contrast-enhanced MR images

SummaryIn meningiomas, a flat, contrast-enhancing, probably dural structure adjacent to the tumor can occasionally be observed on Gadolinium-DTPA enhanced MR images. This so called “meningeal sign” was evaluated with respect to the differential diagnosis of meningiomas in MR imaging. The study included 29 patients with intracranial meningiomas and 24 patients with non-meningeal brain tumors. In all meningiomas, MR studies included T2-weighted as well as unenhanced and Gadolinium-DTPA-enhanced T1-weighted images. In all nonmeningeal tumors, Gd-DTPA-enhanced MR images were available. All images were evaluated with respect to the presence of the “meningeal sign”. In meningiomas, a “meningeal sign” was seen in 15/29 cases on Gadolinium-DTPA-enhanced images. No abnormalities corresponding to the areas of contrast enhancement were found on unenhanced T2- and T1-weighted MR images. In nonmeningeal tumors only 2/24 cases showed a “meningeal sign”. In conclusion, with a sensitivity of 52% and a specificity of 92%, the demonstration of the “meningeal sign” improved the differential diagnosis of intracranial meningiomas in contrast-enhanced MR imaging.

Gd-DTPA enhanced MRI of breast: the most sensitive method for detecting multicentric carcinomas in female breast?

The first publications on the use of magnetic resonance for breast imaging (MRBI) appeared more than 10 years ago. According to the literature between 14% and 47% of all breast carcinomas are multicentric carcinoma (MCC), a substantial number of which are not detected by conventional mammography. In a prospective study our purpose was to establish a clinically relevant procedure with MRBI for women with a single suspect lesion on mammography. Eight (32%) of 25 patients with histologically confirmed carcinoma had an MCC. Seven MCC were detected with MRBI and only one was diagnosed by mammography; one was discovered with neither MRBI nor mammography. MRBI proved to be the superior technique, with a sensitivity of 0.88 compared with 0.13 for mammography.

Initial clinical experience with spiral CT and 3D arterial reconstruction in intracranial aneurysms and arteriovenous malformations

We studied 32 consecutive patients with known or suspected cerebrovascular abnormalities studied with spiral CT following a intravenous bolus injection of iodinated contrast medium with a power injector. Flow was 3 or 4 ml/s. In an attempt to define the appropriate delay time and scan duration a cranial angio-CT without table increment was performed on 10 patients. Enhancement was measured by manually placed regions of interest within the left middle cerebral artery and the inferior sagittal sinus. All patients except one had intraarterial angiography (DSA) for comparison. In 6 patients with an arteriovenous malformation (AVM) follow-up was possible after one and/or two embolisation procedures. These patients had plain and contrast-enhanced spiral CT. The diagnosis was aneurysm in 9 (8 berry aneurysms, one giant fusiform aneurysm), AVM in 13 (all supratentorial) and traumatic arteriovenous fistula in one. In 9 patients there were no detectable pathological vascular findings. After 3D reconstruction the size (between 5 and 28 mm), location and the relationship to the parent vessel of the aneurysms, the extent of the AVMs and the distribution of the embolisation material could be demonstrated clearly. The main feeding vessel(s), nidus and draining veins were reliably shown. The decreased extent of the AVMs after embolisation was clearly demonstrated. There was no difference in diagnosis when DSA and 3D-CT were compared by two independent radiologists. We consider arterial spiral CT with 3D reconstruction to have the potential of offering important diagnostic information for the treatment of intracranial AVMs and aneurysms.

High-resolution conjunctival contrast-enhanced MRI dacryocystography.

Abstract We assessed high-resolution MRI of the lacrimal system with conjunctival contrast enhancement in patients with suspected stenosis. We studied 18 patients with epiphora affecting 22 eyes, using a surface coil, before and after conjunctival and intravenous Gd-DTPA. Stenosis or obstruction of the ducts was found in 18 of 22 cases: at canalicular level in 3 cases, at the sac in 7 cases, and in the nasolacrimal duct in 8 cases. Periductal pathology following surgery to the maxillary sinus or dacryocystorhinostomy was seen in three cases. In conjunction with the findings on syringing and/or conventional dacryocystography, the narrowing was classified as stenosis or obstruction.

Registered image subtraction for CT-, MR- and coronary angiography

Abstract. Conventional post-processing of digital subtraction angiography (DSA) by 3D spiral CT, 3D MRI and 2D DSA is often hampered by extended artefacts due to patient movements during examination. In this paper an image registration procedure prior to the digital subtraction is introduced allowing an enhanced visualization of the contrast agent. The object displacement is detected by analysis of image deformations in small local regions. The motion pattern is used to compute a new synthetic mask of maximum congruence with the contrast medium image. This new mask image is then used in the subsequent subtraction. The algorithm works fully automatically and does not need any interactive placement of landmarks. Results obtained from subtraction of uncorrected and corrected sequences were compared with each other. The registration procedure provided good results in the suppression of subtraction artefacts and in the enhancement of vascular structures. Results are presented from subtraction of 2D and 3D data from CTA, MR mammography and coronary angiography.

MRI (NMR) in the diagnosis of brain-stem tumors

SummaryPatients with a brain-stem tumor were studied with NMR. The full extent of the lesion as well as its relationship with the adjacent structures was clearly demonstrated in all cases. Although NMR is, in many aspects, superior to CT and angiography, these examinations remain useful complementary methods.

Washout and redistribution between immediate and two-hour myocardial images using technetium-99m sestamibi

The aim of this study was to assess whether a clinically relevant change in myocardial sestamibi activity could be documented within the first 120 min following injection (p.i.). In 17 patients planar anterior imaging of the heart was performed 5 min and 120 min p.i. During this time interval, mean decay-corrected myocardial activity declined to 77.9%±9.7% after stress and to 85.7%±7.9% after injection at rest (P<0.05). In 19 patients with angiographically documented coronary artery disease, single-photon emission tomography was performed 5 min and 120 min after injection at maximum stress. For analysis, sestamibi activity was scored semiquantitatively in six left ventricular segments. Furthermore, sestamibi uptake was assessed quantitatively using a circumferential profile method. In 35 of 114 segments the score improved within 120 min p.i. (early fillin); in these segments relative sestamibi activity rose from 69.9%±22.5% to 74.5%±20.8% (P<0.01). In five patients this early fill-in was the only sign of exercise-induced hypoperfusion. In 7 of 114 segments the score deteriorated 120 min p.i. (early tracer washout); in these segments relative sestamibi activity declined from 85.6%±9.9% to 80.1%±10.7% (P<0.02). In three of four patients with early tracer washout the corresponding coronary artery was significantly narrowed. In conclusion, a global myocardial sestamibi washout was registered within the first 120 min after injection. A fill-in of initial defects as well as an early tracer loss could be detected in a relevant number of patients with chronic coronary artery disease during the first 2 h p.i. In these patients the extent of detected reversible perfusion abnormality depends on the chosen time interval between injection and imaging. The results of this study suggest that exercise imaging should be started immediately after injection.

Transcranial Doppler Sonography: Collateral Pathways in Internal Carotid Artery Obstructions

Fifty-four patients with stenoses and occlusions of the extracranial internal carotid artery (ICA) demonstrated by intravenous digital subtraction angiogra phy (IVDSA) were studied by extracranial duplex and transcranial Doppler. Two hundred healthy volunteers served as control group. Intracranial collateralization was demonstrated in 32 patients with ICA stenoses >80% and occlusions. Twelve patients with unilateral and 8 patients with bilateral ICA obstructions >80% showed collateral supply via the anterior (ACA) and/or posterior cerebral artery (PCA). In 5 cases of unilateral ICA oc clusion and in 7 patients with bilateral ICA stenoses >80% and occlusions, the ophthalmic artery and ACA and/or PCA served as collateral vessels. Five pa tients with ICA occlusions showed leptomeningeal anastomoses in the region of the postocclusive middle cerebral artery (MCA). All 54 patients showed normal time-mean flow velocity in the postobstruc tive MCA. In unilateral ICA stenoses >80% and occlusions, the pulsatility in dex in the ipsilateral MCA was reduced in comparison with the contralateral side, indicating that this parameter is more sensitive to hemodynamic effects of ICA obstructions than time-mean velocity.

Magnetic resonance imaging (MRI) in the diagnosis of cerebral arteriovenous angiomas

SummaryEight patients with angiographically confirmed arteriovenous malformations (AVMs) were studied by CT and MRI. MRI scans were performed with a 0.35 Tesla wholebody scanner using three spin-echo sequences (SE 400/35, SE 1600/35, SE 1600/70). In CT and MRI, pathological findings were obtained in all cases. In MRI AVMs were displayed as lesions of low signal intensity in the applied sequences. Full extent of the lesions as well as the relationship to the surrounding structures were clearly demonstrated in MRI in all patients. Based on the characteristic sequence dependent signal intensity property of the lesions, the differential diagnosis in the sense of an AVM could be obtained by MRI in all cases. Concerning topographical imaging and/or differential diagnosis, MRI was superior to CT in 4 out of 8 cases. MRI offers advantages in the demonstration of AVMs of the cerebral midline, especially in brain stem angiomas.