Preoperative T2-weighted Magnetic Resonance Imaging Research Articles

Use of Patient-specific MRI-based Prostate Mold for Validation of Multiparametric MRI in Localization of Prostate Cancer

To demonstrate the use of a patient-specific magnetic resonance imaging (MRI)-based prostate mold to generate histologic sections that directly correlate to axial MRI slices in a patient with anteriorly located prostate cancer. Anteriorly located prostate cancer has traditionally been difficult to detect on digital rectal examination and transrectal ultrasound-guided biopsy. Multiparametric MRI has potential as a valuable tool for the diagnosis and focal treatment of prostate cancer. A significant difficulty to date has been accurate correlation between the magnetic resonance images and histopathologic specimens. A patient-specific mold from a preoperative T2-weighted MRI scan was created to hold and shape the prostate specimen. Slots for slicing were positioned at 6-mm increments coplanar to the axial MRI slices. After surgical excision, the specimen was inked to maintain the orientation and fixed in formalin. The seminal vesicles were excised, and the prostate was oriented in the mold such that the color-coding matched the anatomic labels on the mold. The specimen was sliced with a single blade and the resultant 6-mm tissue blocks were used for histologic analysis. Preoperative multiparametric MRI revealed a lesion in the right anterior transition zone that was positive on T2-weighed MRI, apparent diffusion coefficient maps of diffusion-weighted MRI, magnetic resonance spectroscopy, and dynamic contrast-enhanced MRI. The histologic sections obtained using the mold demonstrated a similar Gleason score 6 (3+3) lesion in the right anterior transition zone, correlating with the MRI findings. The use of patient-specific prostate molds to register the MRI findings with the histopathologic specimen in prostate cancer could offer several benefits compared with current specimen processing techniques. This technique might further validate MRI as an accurate tool for prostate cancer localization and staging.

Gastric leiomyosarcoma manifesting peculiar findings: Radiological–pathological correlation

Reported herein is a gastric leiomyosarcoma, which, nowadays, is extremely rare. Attention was focused not only on pathological findings but also on the histological basis of magnetic resonance imaging (MRI) findings. The patient was a 29-year-old Japanese woman. Preoperative T2-weighted MRI showed a large high-intensity gastric tumor with isointense streaks. The tumor was a broad-based large polypoid lesion and histologically consisted of fascicles of spindled cells having eosinophilic cytoplasm and cigar-shaped nuclei. Immunoreactivity for several smooth muscle markers including desmin on tumor cells, low amplification of both c-kit and PDGFRA cDNA on polymerase chain reaction, and absence of c-kit gene mutation in exons 9 and 11 strongly suggested that the tumor was not a gastrointestinal stromal tumor but a true leiomyosarcoma. In vitro MRI of the fresh tumor was obtained to explain the radiological findings on a morphological basis. In vitro MRI clearly depicted the very high-intensity areas separated by radially extended isointense lines. This radiological finding corresponded best to the most characteristic histological feature, that is, linearly extended fascicles of the tumor cells often with myxedematous change separated by radially elongated thin fibrovascular stroma: in other words, spouting appearance.

Subthalamic nucleus stimulation in Parkinson's disease: Postoperative CT–MRI fusion images confirm accuracy of electrode placement using intraoperative multi-unit recording

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is increasingly used to treat advanced Parkinson's disease (PD). The optimal method for targeting the STN before implanting the definitive DBS electrode is still a matter of debates. Beside methods of direct visualization of the nucleus based on stereotactic magnetic resonance imaging (MRI), the most often used technique for targeting STN consists in recording single-cell activity along exploratory tracks of 10-15mm in length, centered on the theoretical or MRI-defined target coordinates. Single-unit recordings with a microelectrode present various drawbacks. They are time-consuming if correctly performed and a single-cell precision is probably superfluous, taking into account the size of the implanted electrode. In this study, we present an original method of recording and quantification of a multi-unit signal recorded intraoperatively with a semi-microelectrode for targeting the STN. Twelve patients with advanced PD have been included and assessed clinically before and one year after bilateral STN-DBS electrode implantation guided by multi-unit electrophysiological recordings. After one year of chronic stimulation, all patients showed a marked clinical improvement. The motor score of the unified Parkinson's disease rating scale decreased by more than 57% and the required levodopa-equivalent daily dose by 59.5% in on-stimulation off-medication condition compared to off-stimulation off-medication condition. The accuracy of STN-DBS lead placement was confirmed on postoperative computed tomography (CT) scans, which were fused to preoperative T2-weighted MRI. The boundaries of the STN were easily determined by an increase in multi-unit signal amplitude, which was observed on average from 0.492mm below the rostral border of the STN down to 0.325mm above its caudal border. Signal amplitude significantly increased at the both rostral and caudal STN margins (P<0.05) and the level of neuronal activity easily distinguished inside from outside the nucleus. This study showed that STN boundaries could be adequately determined on the basis of intraoperative multi-unit recording with a semi-microelectrode. The accuracy of our method used for positioning DBS electrodes into the STN was confirmed both on CT-MRI fusion images and on the rate of therapeutic efficacy.

Surgical treatment for choroid plexus tumors in the fourth ventricle: brain stem infiltration hinders total extirpation

The significance of surgery for choroid plexus tumors is well established, but surgical resection of those in the fourth ventricle has not been evaluated. This study reviewed five consecutive patients with choroid plexus tumors in the fourth ventricle treated in our institute between 1996 and 2005, focusing on the factors that hindered total extirpation. Two cases were choroid plexus papillomas, and three cases were choroid plexus carcinomas. Preoperative T2-weighted magnetic resonance imaging showed a diffuse high-intensity lesion in the brain stem in four patients. Infiltration into the fourth ventricle floor was apparent in all five patients during surgery, which hindered total resection of the tumors without neurological deterioration. Intraoperative bleeding was well controlled in all five patients by cauterizing the feeding arteries at the early stage of surgery through the telovelar approach. Performance status was improved in all patients postoperatively. All patients with choroid plexus carcinomas underwent radiation therapy after the surgical removal. No patient suffered tumor progression within the follow-up of 24-129 months (mean 64 months). Total resection of choroid plexus tumors in the fourth ventricle is difficult because of invasion into the fourth ventricle floor. Adjuvant therapy for choroid plexus tumors with brain stem infiltration must be established.

Reconstruction of Chronic Achilles Tendon Rupture with the use of Interposed Tissue between the Stumps

Background The gap between the tendon stumps in chronic Achilles tendon rupture has reportedly been filled with interposed scar tissue. In the authors’ clinical experience, this interposed tissue is often thick and resists tension, so they considered it was possible to use the interposed tissue for reconstruction of Achilles tendon rupture. Hypothesis Scar tissue interposed between the tendon stumps has the capacity to form tendon-like repair tissue in patients with chronic Achilles tendon rupture. Study Design Case series; Level of evidence, 4. Methods Six patients with chronic rupture of the Achilles tendon underwent tendon reconstruction with the use of interposed tissue between the stumps. The average time from the primary injury to surgery was 22 weeks (range, 9 to 30 weeks). Preoperative magnetic resonance imaging (MRI), histology of the interposed tissue, and clinical results were evaluated. The average postoperative follow-up period was 31 months (range, 24 to 43 months). Results Preoperative T2-weighted MRI in all cases revealed that chronically ruptured Achilles tendons were thickened and fusiform-shaped with diffuse intratendinous high-signal alterations throughout. Longitudinal high-signal bands were seen throughout the tendon, except at the musculotendinous junction and insertion on the calcaneus. Histologically, scar tissue interposed between the tendon stumps consisted of dense collagen fibers, and degenerative changes were not seen. After surgery, no patient had difficulty in walking or stair climbing, and all were able to perform a single-limb toe raise. The mean preoperative and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scores were 88.2 and 98.3 points, respectively; the difference was statistically significant (P = .0277). Conclusion Interposed tissue between the tendon stumps is suitable for repair of chronic Achilles tendon rupture if preoperative MRI shows a thickened fusiform-shaped Achilles tendon with diffuse intratendinous high-signal alterations throughout.

Preoperative neuroimaging findings as a predictor of the surgical plane of cleavage: prospective study of 100 consecutive cases of intracranial meningioma.

To understand the cause and prevention of postoperative ischemic and/or venous parenchymal infarcts after intracranial meningioma resection, the authors describe the value of neuroimaging in predicting the surgical plane of cleavage. A prospective study of 100 meningiomas was performed, in which tumor size, absence or presence of peritumoral edema, tumor-parenchyma interface, and types of arterial vascularization (that is, dural-meningeal, pial-cortical, or mixed) were correlated with the type of dissection plane (extrapial, subpial, or mixed) encountered at surgery. A direct correlation was found between the tumor size identified on T1-weighted magnetic resonance (MR) imaging sequences and the degree of subpial (nonextrapial) surgical plane of cleavage (p < 0.00001). A similar correlation was found with the grade of peritumoral edema identified on preoperative computerized tomography (CT) scanning (p < 0.0001) or T2-weighted MR imaging sequences (p < 0.00001) and tumor pial vascularization as seen on angiography (p < 0.0001). Nevertheless, the tumor-parenchyma interface on preoperative T2-weighted MR imaging sequences was not predictive of the surgical plane (p > 0.5). The worst clinical outcome was found in the tumors located in eloquent areas and in which a subpial plane was encountered at surgery (p = 0.03). Peritumoral edema on preoperative CT and MR studies and tumor pial vascularization as seen on selective angiography can be used to predict the surgical plane of cleavage in meningiomas. The association between tumor size and a subpial surgical plane may be explained by a more pial vascularization seen on angiography. Meningiomas with a location in eloquent cortex and a subpial dissection plane should be considered a high-risk group.

Association between decreased disc signal intensity in preoperative T2-weighted MRI and a 5-year outcome after lumbar minimally invasive discectomy.

A total of 39 patients who had undergone microdiscectomy or percutaneous nucleotomy for lumbar disc herniation were examined after a follow-up of 5 years. The overall outcome was satisfactory in 80% of the patients treated, and only 1 (3%) patient had been reoperated during the follow-up. Clinical signs and symptoms of lumbar instability were detected in 10 (26%) patients. All these 39 patients had been examined with lumbar magnetic resonance imaging (MRI) on the day preceding the operation; the presence of disc degeneration was graded as severe, mild or non-existent depending on the visual brightness of the discs on T2-weighted images, as compared to the signal intensity of the lumbar vertebrae. None of the 12 patients with no preoperative disc degeneration in MRI suffered from postoperative clinical signs and symptoms of instability as compared to 10 (37%) of the 27 patients with mild or severe disc degeneration suffering from instability (p = 0.04). Thus, the results of the present study imply that the grade of the disc degeneration in preoperative T2-weighted MR images significantly predicted the occurrence of postoperative clinical instability.