Non-enhancing Lesions Research Articles

Adult-onset epilepsy associated with dysembryoplastic neuroepithelial tumors

Dysembryoplastic neuroepithelial tumors (DNET) are benign, localized lesions that typically cause localization-related epilepsy of childhood onset. Although excellent seizure outcomes are expected following surgical resection of focal, benign lesions, reports in pediatric epilepsy series suggest that this may not be the case with DNETs, which may exhibit complex and often multifocal epileptogenesis. We report the characteristics and surgical outcome of an adult- and childhood-onset cohort with this condition. Retrospective cohort of 23 patients seen at two major epilepsy centers, with localization-related epilepsy associated with histopathologically demonstrated DNETs. We assessed clinical, electrographic and surgical outcome features in patients with adult- and childhood-onset epilepsy. We were particularly interested in the level of congruence of EEG and MRI data and the need for intracranial recordings. We evaluated seizure outcomes at last follow-up. The mean age was 33.3 years (range: 5-56 years). Ten patients had adult-onset epilepsy. Thirteen patients (57%) had simple partial, 21 (91%) had complex partial, 16 (70%) had secondarily generalized seizures and 5 patients had only simple partial seizures. Status epilepticus did not occur. Non-enhancing lesions on MRI were located in the temporal lobe in 17 patients, the frontal lobe in 3 patients and the parietal/occipital region in 2 patients. One patient had a DNET that involved both frontal and temporal areas. Ictal scalp EEG and MRI were congruent in 17 patients (74%). Eleven patients (48%) underwent lesionectomies, while the rest required some resection of extralesional cortex as well. Five patients required intracranial EEG. There was no association with cortical dysplasia. Seventeen patients (74%) had an Engel class 1 outcome, in a follow-up period that ranging from 5 to 98 months. We found no difference in outcomes between adult- and childhood-onset cases. Although epileptogenicity was complex, congruence between electro-clinical and neuroimaging studies was high and allowed good surgical outcomes at 1 year of follow-up.

Sporadic adult-onset leukoencephalopathy with neuroaxonal spheroids mimicking cerebral MS

Leukoencephalopathy with neuroaxonal spheroids is a rare cause of severe, subacute dementia that usually presents in childhood and is inherited in an autosomal dominant pattern. The authors present clinical, radiologic, and pathologic features of adult-onset, sporadic cases mimicking cerebral-type progressive MS. Five patients referred to an MS subspecialty clinic from 1999 to 2006 suspected of having primary cerebral MS. All patients were reviewed clinically, radiologically, and pathologically at Mayo Clinic Rochester. Diagnostic brain biopsies were examined by two neuropathologists. All patients had severe, progressive cognitive and motor impairment, often with prominently asymmetrical features and diffuse nonenhancing subcortical white matter lesions on brain MRI. Cerebrovascular and spinal cord imaging were normal. CSF showed elevated neuron-specific enolase without elevated oligoclonal bands or IgG index. Extensive evaluations for alternative diagnoses were unrevealing. Pathologic examination confirmed leukodystrophy with neuroaxonal spheroids and pigmented glia on all patients. Therapies initiated did not alter the severe progressive disease course. Leukoencephalopathy with neuroaxonal spheroids occurs sporadically, in adults, and mimics cerebral-type MS or other leukodystrophies. Brain biopsy may be diagnostic in life; however, no treatment is known to be effective. Pathologic diagnosis is important to avoid potentially toxic therapies aimed at CNS inflammatory diseases such as MS.

The effect of bevacizumab (Avastin) on neuroimaging of brain metastases

Background Bevacizumab is FDA approved to treat colon cancer and is currently used off label for metastatic breast, kidney, and lung cancers. Bevacizumab is a monoclonal antibody that binds to, and inactivates, VEGF and is believed to be antiangiogenic. Case Description The authors report the case of a 54-year-old woman with metastatic infiltrating ductal breast carcinoma who developed left occipital and right parietal intraaxial contrast-enhancing masses on surveillance magnetic resonance imaging (MRI). After surgical resection, she was placed on bevacizumab for control of systemic disease. Six months later, a nonenhancing right occipital lesion was detected on MRI. After stopping bevacizumab therapy, the patient underwent microsurgical resection of the lesion. Histopathologic examination was consistent with metastatic breast cancer indistinguishable from her previously resected enhancing brain metastasis. Six weeks after stopping bevacizumab therapy and 3 weeks after microsurgical resection, a new contrast-enhancing mass was noted on magnetic resonance in the right temporal lobe. Conclusion This case is unique in that we have neuroimaging on prebevacizumab, concurrent bevacizumab, and postbevacizumab brain metastases in the same patient with a single cancer primary, thus, assuring that alterations in neuroimaging characteristics are consistent with bevacizumab effect. As an internal control, it provides strong support for the premise that bevacizumab therapy can confound the diagnosis of brain metastases because of its effect on tumor enhancement.

Pituitary apoplexy as a cause of internal carotid artery occlusion

Occlusion of intracranial arteries by pituitary apoplexy with resulting infarction is a rare occurrence. A 50-year-old man who presented with a history of sudden onset of frontal headache and visual impairment was admitted to another medical centre and MRI revealed a non-enhancing sellar lesion with suprasellar and infrasellar extension. Thereafter, the patient’s consciousness deteriorated progressively and he showed signs of herniation; he was then referred to our centre for further evaluation. CT scanning revealed infarction of the left internal carotid artery territory. Transcranial resection of the tumour followed by a large decompressive craniotomy restored the blood flow in the internal carotid artery. Histological examination revealed the tumour to be a pituitary adenoma that contained formed blood elements. The patient’s neurological status did not improve and he died on the ninth postoperative day despite vigorous treatment for controlling intracranial pressure. This case study documents a rare presentation of pituitary apoplexy that caused signs of raised intracranial pressure due to mechanical obstruction of an internal carotid artery with resulting infarction.

Paradoxical imaging findings in cerebral gliomas

Gliomas represent approximately one-third of all intracranial tumors in adults and commonly present clinically with seizures. We report two seizure patients with paradoxical imaging findings on preoperative grading of their cerebral gliomas. A 53-year-old man with a history of temporal lobe epilepsy originating from a mass in the right medial temporal region (patient 1) and a 44-year-old man with a history of predominantly left sided sensory seizures with a mass in the right posterior parietal region (patient 2) underwent presurgical evaluation including MRI and glucose PET, followed by surgery to remove cerebral tumors associated with seizure onset. Preoperatively, patient 1 had a homogenous non-enhancing lesion on MRI and hypometabolism on PET imaging, suggesting a low-grade tumor. Postoperative histopathology was consistent with a glioblastoma multiforme (grade IV). Patient 2 had a heterogeneous lesion with cyst formation, edema, and contrast enhancement on preoperative MRI imaging, and interictal hypermetabolism on PET scan, thus suggesting a high-grade tumor. Postoperative histopathology was consistent with an oligodendroglioma (grade II) without anaplastic features. We conclude preoperative grading of cerebral gliomas may be inaccurate occasionally even in cases with concordant structural and functional imaging findings. This should be considered when counseling patients.

Sudden onset of paraplegia caused by hemorrhagic spinal epidural angiolipoma. A case report

Spinal epidural angiolipoma is a rare benign tumor containing vascular and mature adipose elements. A slow progressive clinical course was mostly presented and rarely a fluctuating course during pregnancy. The authors report the original case of spontaneous spinal epidural bleeding resulting from thoracic epidural angiolipoma who presented with hyperacute onset of paraplegia, simulating an extradural hematoma. The patient was admitted with sudden non-traumatic hyperacute paraplegia during a prolonged walk. Neurologic examination showed sensory loss below T6 and bladder disturbances. Spinal MRI revealed a non-enhanced heterogeneous thoracic epidural lesion, extending from T2 to T3. A bilateral T2-T4 laminectomy was performed to achieve resection of a lipomatous tumor containing area of spontaneous hemorrhage. The postoperative course was uneventful with complete neurologic recovery. Histologic examination revealed the tumor as an angiolipoma. Because the prognosis after rapid surgical management of this lesion is favorable, the diagnosis of spinal angiolipoma with bleeding should be considered in the differential diagnosis of hyperacute spinal cord compression.

Surgical treatment of a traumatic intracranial epidural haematoma in a dog

A 10-month-old Czech wolf dog was unconscious after being kicked in the head by a horse. The following day, the dog was ataxic and collapsed after several steps. The level of consciousness was decreased. Cranial nerve examination was normal and right postural reactions were decreased. Spinal reflexes were intact in all limbs. The diagnostic work-up included a computed tomography (CT) scan of the head with IV contrast. A lenticular shaped, hyperdense, non-enhancing lesion was observed in the left fronto-parietal region. A diagnosis of intracranial epidural haematoma was made. Two craniotomies were performed on a different day and most of the haematoma was removed. Corticosteroids and antimicrobial therapy were administered. Fifteen days after the surgery, the clinical examinations were unremarkable. Fifteen months later, the owners considered the dog normal. Intracranial subdural or intraparenchymal haematomas have been described in the veterinary literature. To the authors' knowledge, this is the first report of the successful management of an intracranial epidural haematoma in the dog. In humans, these lesions are well described. Common locations are temporal, parietal and frontal regions or a combination of these regions. Patients can be asymptomatic, present with varying clinical signs, or be unconscious. Based on the human literature, following trauma to the head, a CT scan should be performed even if the patient is asymptomatic. Some authors believe that there are not any absolute indications for conservative management versus surgical management.

Eosinophilic Granuloma Presenting as an Epidural Hematoma and Cyst

Langerhans' cell histiocytosis (LCH) is a rare immunologic disorder characterized by histiocyte proliferation in multiple organ systems. Eosinophilic granuloma, a benign bone lesion, represents a focal form of LCH. We experienced a case of Langerhans' cell histiocytosis in a patient who presented with intracranial epidural hematoma and cyst on the midline of the frontal skull. A 10-year-old boy presented with a rapidly growing large scalp mass on the midline frontal area after mild head trauma. The scalp mass was painless and immobile. Plain skull x-ray showed a punched-out bone lesion. Computed tomography and magnetic resonance imaging showed a non-enhancing osteolytic lesion presenting with an epidural hematoma and cyst on the midline of the frontal skull. The lesion of the skull was completely resected and the patient's recovery was uneventful. The acute presentation of a solitary eosinophilic granuloma of skull with an epidural hematoma has been described in only five cases in the literature and we report the first case of LCH presenting as an intracranial epidural hematoma on frontal area.

Non-functional Pituitary Adenoma Detected on 18F-fluorodeoxyglucose Positron Emission Tomography (18F-FDG-PET) in a Patient with Mucosa-associated Lymphoid Tissue Lymphoma

Magnetic resonance imaging (MRI) is the modality of choice for the detection and characterization of a pituitary adenoma. Uptake of 18 F-fluorodeoxyglucose (FDG) by intrasellar tumors, including pituitary adenomas, has been reported in several previous studies. We report a case where a pituitary adenoma was detected on FDG-positron emission tomography (PET), but the tum or was not detected with the use of sellar MRI. A 31-year-old woman was referred to the clinic due to a focal increase of FDG uptake at the pituitary fossa seen on whole body FDG-PET. The patient was receiving chemotherapy due to a recurred B-cell lymphoma of the mucosa-associated lymphoid tissue type. Subsequently, sellar MRI was performed, and images showed a small non-enhancing heterogenous cystic lesion in the midline of the pituitary gland, radiologically suggestive of a Rathke's cleft cyst. However, sellar MRI failed to identify a lesion consistent with a pituitary tumor that corresponded to the site of increased FDG uptake detected by the use of PET, despite the inclusion of a dynamic contrast enhanced sequence. Despite the negative findings of the MRI examination, basal and stimulated levels of the GnRH free α-subunit were profoundly increased. Therefore, we suspected the presence of a non-functional pituitary tumor in addition to a Rathke's cleft cyst, rather than pituitary involvement of a lymphoma, based on the hormone levels and PET scan findings. (J Korean Endocr Soc 23:137~141, 2008)

PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY AFTER RITUXIMAB IN A CASE OF NON-HODGKIN LYMPHOMA

Progressive multifocal leukoencephalopathy (PML) is a rare and usually fatal demyelinating disorder caused by the reactivation of a latent JC virus infection. In non-HIV patients, PML usually occurs as a late consequence of hematologic malignancies or immunodeficiency or after severe and prolonged immunosuppression for transplantation or systemic disease. We report a patient who developed PML shortly after diagnosis of non-Hodgkin lymphoma, with a short course of modest immunosuppression including treatment with rituximab. ### Case report. A 63-year-old woman was diagnosed with low-grade non-Hodgkin lymphoma and began chemotherapy 2 weeks later with rituximab, cyclophosphamide, vincristine, doxorubicin, and prednisolone (R-CHOP). During the third cycle, approximately 7 weeks after beginning treatment, she developed change in mental status with persistent headaches. A brain MRI showed an enhancing white matter abnormality in the right temporal lobe and nonenhancing white matter lesions in the left temporal lobe, right cerebellum, left midbrain, and right pons. Serum chemistries and metabolic studies were …

Histological, CT, and Intraoperative Ultrasound Appearance of Hepatic Tumors Previously Treated by Laparoscopic Radiofrequency Ablation

PurposeThe purpose of this paper is to compare intraoperative biopsy results of previously ablated liver tumors with their preoperative computed tomography (CT) and intraoperative laparoscopic ultrasound (LUS) appearances in patients undergoing repeat radiofrequency ablation (RFA). MethodsSeventy repeat RFA procedures were performed in 59 (13%) patients. Laparoscopically, suspected recurrent and stable appearing foci were biopsied using an 18 G biopsy gun. Preoperative CT and LUS appearances of the previously ablated lesions were compared with core biopsy results. ResultsThere were 33 patients with colorectal cancer, 11 with hepatocellular cancer, 8 with neuroendocrine tumors, and 7 with other tumor types. Two hundred lesions were treated by RFA in these 70 repeat ablations. Suspected recurrent tumor foci were enhanced on CT and produced a more finely stippled echo pattern on LUS. Biopsy confirmed recurrent tumor in 72 of 84 such lesions. Previously ablated foci had a CT appearance of a hypodense, nonenhancing lesion without evidence of adjacent enhancing foci. Laparoscopic ultrasound appearance was of a hypoechoic lesion with a coarse internal pattern with the tracks of the ablation catheter probes often still visible. Biopsy found necrotic tissue in 21 of 22 such lesions appearing radiologically to be without recurrence. Biopsy of an ablated focus adjacent to an area of suspected recurrence showed necrotic tissue in 17 of 22 lesions and viable cancer in 5. ConclusionCT and LUS appearance of previously ablated foci showed good correlation with core biopsies. CT scan is reliable in following RFA lesions, without the need for routine biopsy. LUS reliably distinguished recurrent from ablated lesions in patients undergoing repeat ablation.

Diffusion‐weighted imaging in brain aspergillosis

Brain aspergillosis is a rare pathology, occurring mainly in immunocompromised patients, responsible for multiple cerebral septic infarctions. Some researchers have described magnetic resonance (MR) findings in cerebral invasive aspergillosis, but diffusion-weighted imaging (DWI) has rarely been reported, especially in typical non-enhancing lesions, while it may be helpful for early differential diagnosis and may allow earlier antifungal treatment. We describe three cases of patients presenting brain aspergillosis, with MR imaging including diffusion-weighted sequences and apparent diffusion coefficient (ADC) cartography. The three patients described in this study presented a total of 23 circular lesions, and one patient presented an infarction area in the territory of the right middle cerebral artery. Lesions were ring-enhancing for one patient, and presented no enhancement for the other two. Eleven lesions were very bright on DWI, with reduced ADC values. Twelve lesions, either enhancing or not enhancing, presented a 'target-like' aspect with central and peripheral hypointense areas on DWI, corresponding to higher ADC value areas, and intermediate marked hypersignal on DWI. This typical aspect of aspergillosis lesions on DWI may allow early diagnosis and treatment of cerebral aspergillosis, and is helpful for differentiating aspergillosis lesions from other infectious or malignant lesions affecting immunocompromised patients.

Imaging of cerebellopontine angle lesions: an update. Part 2: intra-axial lesions, skull base lesions that may invade the CPA region, and non-enhancing extra-axial lesions

Computed tomography (CT) and magnetic resonance (MR) imaging reliably demonstrate typical features of vestibular schwannomas or meningiomas in the vast majority of mass lesions responsible for cerebellopontine angle (CPA) syndrome. However, a large variety of unusual lesions can also be encountered in the CPA. Covering the entire spectrum of lesions potentially found in the CPA, these articles explain the pertinent neuroimaging features that radiologists need to know to make clinically relevant diagnoses in these cases, including data from diffusion- and perfusion-weighted imaging or MR spectroscopy, when available. A diagnostic algorithm based on the lesion's site of origin, shape and margins, density, signal intensity and contrast material uptake is also proposed. Non-enhancing extra-axial CPA masses are cystic (epidermoid cyst, arachnoid cyst, neurenteric cyst) or contain fat (dermoid cyst, lipoma). Tumours can also extend into the CPA by extension from the skull base (paraganglioma, chondromatous tumours, chordoma, cholesterol granuloma, endolymphatic sac tumour). Finally, brain stem or ventricular tumours can present with a significant exophytic component in the CPA that may be difficult to differentiate from an extra-axial lesion (lymphoma, hemangioblastoma, choroid plexus papilloma, ependymoma, glioma, medulloblastoma, dysembryoplastic neuroepithelial tumour).

Differentiation of Glioblastoma Multiforme and Single Brain Metastasis by Peak Height and Percentage of Signal Intensity Recovery Derived from Dynamic Susceptibility-Weighted Contrast-Enhanced Perfusion MR Imaging

Glioblastoma multiforme (GBM) and single brain metastasis (MET) are the 2 most common malignant brain tumors that can appear similar on anatomic imaging but require vastly different treatment strategy. The purpose of our study was to determine whether the peak height and the percentage of signal intensity recovery derived from dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion MR imaging could differentiate GBM and MET. Forty-three patients with histopathologic diagnosis of GBM (n=27) or MET (n=16) underwent DSC perfusion MR imaging in addition to anatomic MR imaging before surgery. Regions of interest were drawn around the nonenhancing peritumoral T2 lesion (PTL) and the contrast-enhancing lesion (CEL). T2* signal intensity-time curves acquired during the first pass of gadolinium contrast material were converted to the changes in relaxation rate to yield T2* relaxivity (Delta R2*) curve. The peak height of maximal signal intensity drop and the percentage of signal intensity recovery at the end of first pass were measured for each voxel in the PTL and CEL regions of the tumor. The average peak height for the PTL was significantly higher (P=.04) in GBM than in MET. The average percentage of signal intensity recovery was significantly reduced in PTL (78.4% versus 82.8%; P=.02) and in CEL (62.5% versus 80.9%, P<.01) regions of MET compared with those regions in the GBM group. The findings of our study show that the peak height and the percentage of signal intensity recovery derived from the Delta R2* curve of DSC perfusion MR imaging can differentiate GBM and MET.

Image fusion of fluid-attenuated inversion recovery magnetic resonance imaging sequences for surgical image guidance

Background Nonenhancing brain lesions can be relatively poorly defined on volumetric data sets routinely used for surgical guidance. Fluid-attenuated inversion recovery MRI sequences can provide better margin visualization of nonenhancing or poorly enhancing lesions. Methods Using image fusion programs, we combined data sets of SPGR imaging pulse sequence or volumetric CT with volumetrically acquired FLAIR sequences and subsequently used the fused data set for image-guided surgery. This technique was used in 50 surgical cases. Of these, 9 were nonenhancing intrinsic brain tumors, 13 were partially enhancing tumors, and 11 were enhancing tumors. In addition, FLAIR fusion was selectively used for 6 nontumoral lesions and in 11 nonlesional epilepsy surgery cases. Results Image guidance using the fused data set was accurate in all 50 cases. Despite the lack of enhancement, 3 of the 9 nonenhancing tumors were found to be high grade. One of the low-grade tumors was associated with considerable areas of gliotic change not considered to represent tumor on permanent histology. In all other cases, the FLAIR-bright resected margins were consistent with tumor, not gliosis. Radical resection (>95% volume) was achieved in 21 of 23 tumor cases in which this had been the preoperative intent. Conclusions Nonenhancing lesions are often poorly demarcated not only on imaging studies, but also during surgery. Fluid-attenuated inversion recovery fusion allows resection of such lesions using intraoperative computer image guidance. Complementary FLAIR information can also occasionally be useful during surgical approaches to enhancing lesions or in nontumor cases. It must be kept in mind that FLAIR has high sensitivity but low specificity. Fluid-attenuated inversion recovery abnormalities do not obviate the need for mapping in potentially functional areas.

ECT in Patients With Intracranial Masses

ECT in Patients With Intracranial Masses

Human herpesvirus-6 encephalitis following allogeneic hematopoietic stem cell transplantation

Immunosuppressive monoclonal antibodies directed to immune system cells may reduce rejection and graft versus host disease (GvHD) after allogeneic stem cell transplantation (SCT), but can increase the risks of viral infection. Here, we report human herpes virus-6 (HHV-6) encephalitis despite antiviral prophylaxis in 5 of 43 (11.6%) patients receiving alemtuzumab supported conditioning. Encephalitis occurred at 41-103 days (median 60 days) presenting with confusion in all patients, combined with amnesia (n=3) or seizures (n=2). MRI revealed non-specific white matter changes in two and a non-enhancing medial temporal lobe lesion in three patients. Cerebrospinal fluid (CSF) PCR amplification for HHV-6 was positive in all five patients, (600-2 25 000 (median 4700) copies/ml CSF), while analysis of peripheral blood revealed 100-22 500 (median 1200) viral copies/ml plasma. CSF protein was elevated in four patients, with minimal CSF pleocytosis. Intravenous foscarnet produced neurological improvement at 8-13 (median 11) days and negative plasma PCR at 30-66 (median 50) days. Four patients had complete neurological recovery, but one patient with persistent viral DNA in the CSF succumbed to progressive encephalopathy. Given this high incidence of HHV-6 and the possibility of successful outcome with prompt treatment, a high index of suspicion of this disorder is required in recipients of monoclonal antibody supported allografts.

Multislice Brain Myelin Water Fractions at 3T in Multiple Sclerosis

To evaluate a multislice nonlinearly-spaced 12-echo imaging sequence at 3T covering the supratentorial brain for the quantification of myelin water fraction (MWF) in multiple sclerosis (MS) patients. Eighty-nine patients with, or at risk of, MS (69 relapsing remitting MS [RRMS], 7 secondary progressive MS [SPMS], 13 clinically isolated syndrome [CIS]) and 28 controls were studied. Twelve-echo datasets were acquired using a multislice T2 prep spiral imaging sequence and were fitted using a nonnegative least squares algorithm. The mean MWF within normal appearing white matter (NAWM), contrast-enhancing (CE), and nonenhancing T2 lesions were calculated. Mean MWF in white matter for controls was 11.3%. Mean MWF was significantly reduced in NAWM of MS patients (10.6%, P= .004) relative to controls. SPMS/RRMS patients with disease duration >5 years (10.3%) had lower MWF compared to CIS/RRMS with disease duration <or=5 years (10.8%, P= .03). Mean MWF was reduced by 26% and 29% within both CE (P < .0001) and nonenhancing T2 lesions (P < .0001) relative to controls. Using a multicomponent T2 sequence at 3T, a significant decrease in the supratentorial MWF was observed in MS NAWM and lesions relative to controls. The method was sensitive to detect white matter changes early in the disease process.

Cholesteatoma of the Renal Pelvis Diagnosed by Computerized Tomography

A56-year-old white male had been seen by general practitioners and urologists for complaints of intermittent macroscopic and microscopic hematuria during the last year. Bacteriuria and desquamated epithelial cells were identified on 3 prior occasions and treated with antibiotics. Cystoscopy twice and ultrasonograms of the kidney and bladder were negative. The patient was hospitalized, and voided urine specimen revealed 5 to 10 red blood cells per high power field, as well as desquamated epithelial cells and a specific gravity of 1,020. Hemoglobin was 13.4 gm, hematocrit was 38%, and differential count and blood chemistry studies were negative. Purified protein derivative tuberculin test was positive with a2c minduration, and history revealed active pulmonary tuberculosis treated approximately 15 years ago. Preenhancement computerized tomography demonstrated a laminated onion skin-like, heterogeneously dense mass in the right renal pelvis (part A of figure, arrow). An early parenchymal phase helical computerized tomogram showed minimal enhancement of the pelvic lining consistent with the inflammatory process of pyelitis (part B of figure, arrow). The mass did not enhance. An irregular, contoured, nonenhancing cystic lesion was shown at the corticomedullary junction, most likely representing a caliceal diverticulum. The onion skin-like mass in the pelvis could have been caused by a collection of debris, a precursor to a matrix stone, myceliatoma or cholesteatoma. However, there was no extension of mycelia into the ureter and collecting system, and no confirmed mycelia in the urine. Enhancement of areas of thickened epithelium in the pelvis with a characteristic tree bark appearance favors a chronic inflammatory process but this is also seen in cases of squamous metaplasia and malacoplakia. Desquamated keratin produced by squamous metaplasia may form keratin balls in the pelvis, ie

A study of subtle blood brain barrier disruption in a placebo-controlled trial of natalizumab in relapsing remitting multiple sclerosis

Natalizumab, an anti-alpha4 integrin antibody, significantly reduces the number of visibly enhancing multiple sclerosis (MS) lesions. In this substudy of a 2-year trial of natalizumab monotherapy versus placebo, contrast-enhanced imaging investigated for subtle blood brain barrier (BBB) leakage in relapsing remitting (RRMS) patients, and whether such leakage is modified by natalizumab. After 24 weeks on treatment, 40 patients from 3 centres (27 on natalizumab and 13 on placebo) were studied. T1 weighted images were obtained before and at set timepoints up to 46 minutes after gadolinium (Gd)-DTPA (0.3 mmol/kg to 18 patients, 0.15 mmol/kg to 22). Paired regions of interest were placed around non-enhancing lesions and contralateral normal appearing white matter (NAWM). BBB leakage was inferred through post-Gd T1 weighted signal intensity (SI) change. SI change was greater in T2 non-enhancing lesions than paired NAWM at all timepoints (P<0.005), indicating BBB leakage in lesions. No significant difference in inferred BBB leakage was observed between treatment arms as measured by SI change of lesions (P>0.05 for all timepoints, joint test P=0.24), or in SI change of NAWM (joint test P=0.37). T1 hypointense and isointense lesions exhibited similar SI changes (joint test P=0.12). There is evidence of a subtle BBB leakage within visibly non-enhancing lesions in RRMS that was not modified by alpha4 integrin blockade in this substudy cohort.