Distance Transforms in Multi Channel MR Image Registration

Deformable registration techniques play vital roles in a variety of medical imaging tasks such as image fusion, segmentation, and post-operative surgery assessment. In recent years, mutual information has become one of the most widely used similarity metrics for medical image registration algorithms. Unfortunately, as a matching criteria, mutual information loses much of its effectiveness when there is poor statistical consistency and a lack of structure. This is especially true in areas of images where the intensity is homogeneous and information is sparse. Here we present a method designed to address this problem by integrating distance transforms of anatomical segmentations as part of a multi-channel mutual information framework within the registration algorithm. Our method was tested by registering real MR brain data and comparing the segmentation of the results against that of the target. Our analysis showed that by integrating distance transforms of the the white matter segmentation into the registration, the overall segmentation of the registration result was closer to the target than when the distance transform was not used.

Sequential magnetic resonance imaging finding of intramedullary spinal cord abscess including diffusion weighted image: a case report

Intramedullary spinal cord abscess (ISCA) is a rare infection of the central nervous system. We describe the magnetic resonance imaging (MRI) findings, including the diffusion-weighted imaging (DWI) findings, of ISCA in a 78-year-old man. The initial conventional MRI of the thoracic spine demonstrated a subtle enhancing nodule accompanied by significant edema. On the follow-up MRI after seven days, the nodule appeared as a ring-enhancing nodule. The non-enhancing central portion of the nodule appeared hyperintense on DWI with a decreased apparent diffusion coefficient (ADC) value on the ADC map. We performed myelotomy and surgical drainage, and thick, yellowish pus was drained.

Cervical intramedullary epidermoid cyst with liquid contents

Intramedullary spinal epidermoid cysts are benign ectopic embryological growths with reported incidence of less than 1% of intramedullary tumors. In this case we report an unusual cervical intramedullary epidermid with liquid contents. A 40-year-old patient presented with progressive weakness of all four limbs of four months duration, bowel and bladder disturbances of two days duration, pain and paresthesias in all four limbs. Magnetic resonance imaging (MRI) revealed a well defined intramedullary lesion extending from C2-C3 level with widening of the cord. The lesion was hypointense on T1W images, hyperintense on T2W and fluid attenuation and inversion recovery images with thin rim of enhancement after contrast administration. Histopathological examination of the excised specimen revealed epidermal lining and keratinous material features of an epidermoid cyst. As in present case, rarely epidermoid cyst can have clear contents, and an MRI finding can closely mimic the features of arachnoid cyst, findings not classical and is different than described in literature.

Posterior reversible encephalopathy syndrome in a case of postoperative spinal extradural haematoma: case report and review of literature

A 14-year-old girl presented with progressive paraparesis and paresthesia of one-year duration. Magnetic resonance imaging revealed a T6 vertebral hemangioma with epidural compression on the spinal cord. Following angiography and embolization, she underwent dorsal laminectomy and excision of the soft tissue component compressing the cord. In the postoperative period she had rapid worsening of lower limb power and imaging demonstrated an epidural haematoma at the operative site. The patient was taken up for urgent re-exploration and evacuation of haematoma. Postoperatively the patient complained of visual failure, headache and had multiple episodes of seizures. An magnetic resonance imaging brain showed characteristic features of posterior reversible encephalopathy syndrome (PRES) and the patient improved gradually after control of hypertension. This is the first documented case of PRES following spinal cord compression in a patient without any known risk factors. We postulate the possible mechanism involved in its pathogenesis.

TOPOLOGY PRESERVING AUTOMATIC SEGMENTATION OF THE SPINAL CORD IN MAGNETIC RESONANCE IMAGES

Magnetic resonance images of the spinal cord play an important role in studying neurological diseases, particularly multiple sclerosis, where spinal cord atrophy can provide a measure of disease progression and disability. Current practices involve segmenting the spinal cord manually, which can be an inconsistent and time-consuming process. We present an automatic segmentation method for the spinal cord using a combination of deformable atlas based registration and topology preserving classification. Using real MR data, our method is shown to be highly accurate when compared to segmentations by manual raters. In addition, our results always maintain the correct topology of the spinal cord, therefore providing segmentations more consistent with the known anatomy.

Nonmyxoid mediastinal lipoblastoma in a 2-year-old girl: Case report with US, CT, and MRI findings

Lipoblastomas are rare, benign tumors of mesenchymal origin that contain adipose tissue. They usually develop in the soft tissues of an extremity in infants, children, and young adolescents. We report the case of a 22-month old girl referred to our staff for swelling in the supraclavicular fossa, which was observed when the child cried. The ulstrasonographic examination revealed a mass in the anterosuperior portion of the mediastinum that extended into the right supraclacular fossa. The lesion was weakly hyperechoic with clear-cut margins and did not appear to invade surrounding tissues. On CT, it appeared inhomogeneously hypodense with denitometric characteristics of adipose tissue. On MRI, it was hyperintense on both T1- and T2-weighted sequences and reduced signal intensity in FAT SAT sequences. In light of the imaging features and predominant adipose tissue component, the mass was diagnosed as a mediastinal lipoblastoma, and this diagnosis was confirmed by surgical histology.

Hypertrophic olivary degeneration after resection of a pontine cavernous malformation: a case report

We report the case of a 35 year old African American female who developed hypertrophic olivary degeneration secondary to resection of a pontine cavernous malformation. The patient initially complained of headaches and diplopia. Unenhanced computed tomography (CT) and magnetic resonance images (MRI) of the brain revealed a left pontine cavernous malformation with scattered foci of recent and remote hemorrhage. The patient subsequently underwent surgical resection of the lesion. Follow up MRI 7 months post surgery demonstrated hypertrophy and T2 signal hyperintensity in the ipsilateral inferior olivary nucleus secondary to hypertrophic olivary degeneration. Familiarity with this diagnosis and its imaging characteristics is required of the radiologist to prevent erroneous diagnoses of other pathology.

Comparison of high-resolution ultrasound and MR-enterography in patients with inflammatory bowel disease

AIM: To compare the results of high-resolution ultrasound (HR-US) and magnetic resonance enterography (MRE) examinations in patients with inflammatory bowel disease (IBD).

METHODS: The reports of 250 consecutive cases with known IBD, who had an MRE and HR-US examination, were retrospectively analyzed. Using a patient-based approach we evaluated morphological disease features such as affected bowel wall, stenosis, abscess and fistula. The comparison between the two modalities was based on the hypothesis, that any pathological change described in any imaging modality was a true finding, as no further standard of reference was available for complete assessment.

RESULTS: Two hundred and fifty examinations representing 207 different patients were evaluated. Both modalities assessed similar bowel wall changes in 65% of the examinations, with more US findings in 11% and more MRE findings in 15%. When the reports were analyzed with regard to “bowel wall inflammation”, US reported more findings in 2%, while MRE reported more findings in 53%. Stenoses were assessed to be identical in 8%, while US found more in 3% and MRE in 29% (P < 0.01). For abscess detection, US showed more findings in 2% (n = 4) while MRE detected more in 6% (n = 16). US detected more fistulas in 1% (n = 2), while MRE detected more in 13% (n = 32) (P < 0.001). The most common reason for no detected pathology by US was a difficult to assess anatomical region (lesser pelvis, n = 72).

CONCLUSION: US can miss clinically relevant pathological changes in patients with IBD mostly due to difficulty in assessing certain anatomical regions.

Factors affecting the outcome of extraperitoneal laparoscopic radical prostatectomy: pelvic arch interference and depth of the pelvic cavity

Purpose

To determine the effect of pelvic arch interference and the depth of the pelvic cavity, as shown on preoperative magnetic resonance imaging (MRI), on the performance of extraperitoneal laparoscopic radical prostatectomy (ELRP).

Materials and Methods

In 115 patients, pelvic bone images were obtained at the time of prostate MRI before ELRP. In the reconstructed sagittal plane, we measured the true conjugate diameter, the obstetric conjugate diameter, the difference between the true and obstetric diameters, and the distance between the true conjugate and the prostate apex (pelvic depth). We analyzed which factors were associated with operative time (OT), estimated blood loss (EBL), and positive surgical margins (PSMs).

Results

The difference between the true and obstetric conjugate diameters was 12.7±3.7 mm, and the pelvic depth was 59.9±6.0 mm. The OT, EBL, and the rate of PSMs were 260.1±91.1 minutes, 633.3±524.7 ml, and 19% (22/115), respectively. According to multiple linear regression analysis, predictors of a higher EBL included pelvic depth (3.0% higher per 1 mm increase in diameter difference, p=0.01) and prostate volume (1.5% higher per 1 cc increase in prostate volume, p=0.002). Factors associated with a longer OT were pelvic depth (p=0.04), serum prostate-specific antigen (p=0.04), prostate volume (p=0.02), and Gleason score (p=0.001). For PSMs, only pT2 was an independent factor.

Conclusions

Our results suggest that the depth of the pelvic cavity and prostate volume may increase surgical difficulty in patients undergoing ELRP.

Current trends in staging rectal cancer

Management of rectal cancer has evolved over the years. In this condition preoperative investigations assist in deciding the optimal treatment. The relation of the tumor edge to the circumferential margin (CRM) is an important factor in deciding the need for neoadjuvant treatment and determines the prognosis. Those with threatened or involved margins are offered long course chemoradiation to enable R₀ surgical resection. Endoanal ultrasound (EUS) is useful for tumor (T) staging; hence EUS is a useful imaging modality for early rectal cancer. Magnetic resonance imaging (MRI) is useful for assessing the mesorectum and the mesorectal fascia which has useful prognostic significance and for early identification of local recurrence. Computerized tomography (CT) of the chest, abdomen and pelvis is used to rule out distant metastasis. Identification of the malignant nodes using EUS, CT and MRI is based on the size, morphology and internal characteristics but has drawbacks. Most of the common imaging techniques are suboptimal for imaging following chemoradiation as they struggle to differentiate fibrotic changes and tumor. In this situation, EUS and MRI may provide complementary information to decide further treatment. Functional imaging using positron emission tomography (PET) is useful, particularly PET/CT fusion scans to identify areas of the functionally hot spots. In the current state, imaging has enabled the multidisciplinary team of surgeons, oncologists, radiologists and pathologists to decide on the patient centered management of rectal cancer. In future, functional imaging may play an active role in identifying patients with lymph node metastasis and those with residual and recurrent disease following neoadjuvant chemoradiotherapy.

Primary clear cell carcinoma in the liver: CT and MRI findings

AIM: To retrospectively analyze the computed tomography (CT) and magnetic resonance imaging (MRI) appearances of primary clear cell carcinoma of the liver (PCCCL) and compare the imaging appearances of PCCCL and common type hepatocellular carcinoma (CHCC) to determine whether any differences exist between the two groups.

METHODS: Twenty cases with pathologically proven PCCCL and 127 cases with CHCC in the Second Affiliated Hospital of Sun Yat-sen University were included in this study. CT or MRI images from these patients were retrospectively analyzed. The following imaging findings were reviewed: the presence of liver cirrhosis, tumor size, the enhancement pattern on dynamic contrast scanning, the presence of pseudo capsules, tumor rupture, portal vein thrombosis and lymph node metastasis.

RESULTS: Both PCCCL and CHCC were prone to occur in patients with liver cirrhosis, the association rate of liver cirrhosis was 80.0% and 78.7%, respectively (P > 0.05). The mean sizes of PCCCL and CHCC tumors were (7.28 ± 4.25) cm and (6.96 ± 3.98) cm, respectively. Small HCCs were found in 25.0% (5/20) of PCCCL and 19.7% (25/127) of CHCC cases. No significant differences in mean size and ratio of small HCCs were found between the two groups (P = 0.658 and 0.803, respectively). Compared with CHCC patients, PCCCL patients were more prone to form pseudo capsules (49.6% vs 75.0%, P = 0.034). Tumor rupture, typical HCC enhancement patterns and portal vein tumor thrombosis were detected in 15.0% (3/20), 72.2% (13/18) and 20.0% (4/20) of patients with PCCCL and 3.1% (4/127), 83.6% (97/116) and 17.3% (22/127) of patients with CHCC, respectively. There were no significant differences between the two groups (all P > 0.05). No patients with PCCCL and 2.4% (3/127) of patients with CHCC showed signs of lymph node metastasis (P > 0.05).

CONCLUSION: The imaging characteristics of PCCCL are similar to those of CHCC and could be useful for differentiating these from other liver tumors (such as hemangioma and hepatic metastases). PCCCLs are more prone than CHCCs to form pseudo capsules.

Sprengel deformity: magnetic resonance imaging findings in two pediatric cases

The characteristics of Sprengel deformity, which is also called congenital high scapula, are malposition and dysplasia of the affected scapula, with possible omovertebral connection. The aim of the present study was mainly to present the magnetic resonance imaging (MRI) findings of two pediatric cases of Sprengel deformity. A 7-year-old girl and a 9-year-old boy with deformities in their right shoulder were studied. Plain radiographs were obtained. MRI was performed for both children. The fibrous omovertebral connection is depicted in its longest form in one plane. Omovertebral band is best screened in coronal and axial cross sections. We are introducing a new MRI sign which we named as "Ra's eye" to define the appearance of omovertebral band within the surrounding fat tissue.

Orbital plasmablastic lymphoma with remission following chemotherapy

We report the case of a middle-aged HIV-positive man who presented with proptosis and retro-ocular pain. On CT and MR imaging, a retro-orbital enhancing mass was seen, and PET/CT revealed this lesion as well as a similarly characterized mass in the nasopharynx to be hypermetabolic. Biopsy and subsequent pathological characterization revealed this mass to be plasmablastic lymphoma (PBL), a rare form of non-Hodgkin's lymphoma associated with HIV-infection. PBL is a diffuse B-cell lymphoma with characteristic cell marker patterns. The most common site of this malignancy is within the oral cavity. This case constitutes an unusual orbital manifestation of plasmablastic lymphoma as well as an unusual case in its response to chemotherapy. This case illustrates the importance of functional imaging with PET/CT in the diagnosis, management, and follow-up of plasmablastic lymphoma.

A patient with splenic marginal zone lymphoma presenting with spastic paraplegia as the initial symptom

In this report, we describe the case of a patient with splenic marginal zone lymphoma (SMZL) who presented with spastic paraplegia as the initial symptom. A 42-year-old male developed progressive spastic paraplegia over 4 months. His neurologic examination revealed paraplegia with pyramidal syndrome, hypoesthesia below the T1 level, and anal hypotonia. Magnetic resonance imaging (MRI) of the spinal cord revealed an extensive high-intensity signal in T2-weighted sequences and swelling involving the thoracic region and conus medullaris. A laboratory test revealed presence of the serum M component. Abdominal computed tomography images showed moderate splenomegaly. Abnormal lymphocytes of B-cell lineage markers (CD19+, CD20+, and CD25+; surface immunoglobulin κ expression; IgD+ and IgM+) were found in the peripheral blood, cerebrospinal fluid, bone marrow and spleen. Splenectomy confirmed the SMZL diagnosis. After the completion of chemotherapy, the patient was in complete remission, and spinal MRI findings were normal. Intramedullary spinal cord involvement in SMZL is extremely rare, and, to the best of our knowledge, this is the first case of SMZL with intramedullary spinal cord involvement associated with clinical and radiologic signs without the involvement of cerebral structures. Spastic paraplegia can be the initial presentation of SMZL.

Multiparametric MRI biomarkers for measuring vascular disrupting effect on cancer

Solid malignancies have to develop their own blood supply for their aggressive growth and metastasis; a process known as tumor angiogenesis. Angiogenesis is largely involved in tumor survival, progression and spread, which are known to be significantly attributed to treatment failures. Over the past decades, efforts have been made to understand the difference between normal and tumor vessels. It has been demonstrated that tumor vasculature is structurally immature with chaotic and leaky phenotypes, which provides opportunities for developing novel anticancer strategies. Targeting tumor vasculature is not only a unique therapeutic intervention to starve neoplastic cells, but also enhances the efficacy of conventional cancer treatments. Vascular disrupting agents (VDAs) have been developed to disrupt the already existing neovasculature in actively growing tumors, cause catastrophic vascular shutdown within short time, and induce secondary tumor necrosis. VDAs are cytostatic; they can only inhibit tumor growth, but not eradicate the tumor. This novel drug mechanism has urged us to develop multiparametric imaging biomarkers to monitor early hemodynamic alterations, cellular dysfunctions and metabolic impairments before tumor dimensional changes can be detected. In this article, we review the characteristics of tumor vessels, tubulin-destabilizing mechanisms of VDAs, and in vivo effects of the VDAs that have been mostly studied in preclinical studies and clinical trials. We also compare the different tumor models adopted in the preclinical studies on VDAs. Multiparametric imaging biomarkers, mainly diffusion-weighted imaging and dynamic contrast-enhanced imaging from magnetic resonance imaging, are evaluated for their potential as morphological and functional imaging biomarkers for monitoring therapeutic effects of VDAs.

Diffuse infiltrative lesion of the breast: clinical and radiologic features

The purpose of this paper is to show the clinical and radiologic features of a variety of diffuse, infiltrative breast lesions, as well to review the relevant literature. Radiologists must be familiar with the various conditions that can diffusely involve the breast, including normal physiologic changes, benign disease and malignant neoplasm.

A giant left atrium in rheumatic mitral stenosis

Enlargement of left atrium (LA) is not infrequently observed in patients with rheumatic mitral stenosis. We recently met a patient who had a giant LA associated with severe mitral stenosis. The right ventricle had almost collapsed due to compression by the LA. Mitral valve surgery was performed for mitral stenosis and the postoperative course was uneventful. Thus, we suggest that clinicians should not delay corrective surgery for severe mitral stenosis solely on account of a huge LA.

Imaging of gastroenteropancreatic neuroendocrine tumors

Imaging of gastroenteropancreatic neuroendocrine tumors can be broadly divided into anatomic and functional techniques. Anatomic imaging determines the local extent of the primary lesion, providing crucial information required for surgical planning. Functional imaging, not only determines the extent of metastatic disease spread, but also provides important information with regard to the biologic behavior of the tumor, allowing clinicians to decide on the most appropriate forms of treatment. We review the current literature on this subject, with emphasis on the strengths of each imaging modality.

High-field MRI for diagnosis of fatty liver and fat grading: recent research progress

The incidence of fatty liver has been increasing gradually. The development of magnetic resonance imaging (MRI) has increased the sensitivity and specificity for diagnosis of fatty liver. Currently, multiple MRI methods, including fat-suppression sequence, chemical shift, contrast-enhanced MRI and magnetic resonance spectroscopy (MRS), are available for detection and quantification of fatty liver. MR fat-suppression sequence, especially opposed-phase and in-phase chemical shift gradient-echo sequence, is particularly important for detection of fatty liver. MRS is used to quantify liver fat content at the molecular level. In this article, we review the recent progress in research of high-field MRI for diagnosis of fatty liver and fat grading.

Imaging in staging and management of pancreatic ductal adenocarcinoma

Pancreatic cancer is a relatively common malignancy of the gastrointestinal tract for which complete surgical excision remains the only curative option. Being infiltrative in nature and bearing a complex anatomical relationship with various organs, peritoneal ligaments and vascular structures, accurate anatomical staging is key in treatment of these patients. In this article, we will discuss and provide a brief overview of anatomy and use of imaging in staging pancreatic cancer.

Brain imaging studies in Leber's congenital amaurosis: new radiologic findings associated with the complex trait

Purpose

To report the incidence and new findings of abnormal brain imaging studies associated with patients initially diagnosed with Leber's congenital amaurosis (LCA) without definite systemic abnormalities and to determine the need for brain imaging studies in these patients.

Methods

A retrospective review of medical records was performed in 83 patients initially diagnosed as LCA and without definite systemic abnormalities before the age of 6 months in 2 tertiary referral centers. Brain magnetic resonance imaging was performed in 31 of 83 patients (37.3%).

Results

Six of 31 patients (19%) had radiologically documented brain abnormalities. Two patients had cerebellar vermis hypoplasia, 1 patient showed an absence of septum pellucidum, 2 subjects showed mild external hydrocephalus, and 1 patient was found to have a small cerebellum.

Conclusions

Approximately one fifth of the LCA patients in whom brain imaging was performed were associated with brain abnormalities, including the absence of septum pellucidum, which has not been documented in the literature. Brain imaging is mandatory in patients primarily diagnosed with LCA, even without definite neurologic or systemic abnormalities.

Retrorectal tumors in adults: Magnetic resonance imaging findings

AIM: To retrospectively evaluate the magnetic resonance imaging (MRI) features of adult retrorectal tumors and compare with histopathologic findings.

METHODS: MRI features of 21 patients with preoperative suspicion of retrorectal tumors were analyzed based on the histopathological and clinical data.

RESULTS: Fourteen benign cystic lesions appeared hypointense on T1-weighted images, and hyperintense on T2-weighted images with regular peripheral rim. Epidermoid or dermoid cysts were unilocular, and tailgut cysts were multilocular. Presence of intracystic intermediate signal intensity was observed in one case of tailgut cyst with a component of adenocarcinoma. Six solid tumors were malignant lesions and showed heterogeneous intensity on MRI. Mucinous adenocarcinomas showed high signal intensity on T2-weighted and mesh-like enhancing areas on fat-suppressed T2-weighted images. There was a fistula between the mass and anus with an internal opening in mucinous adenocarcinomas arising from anal fistula. Gastrointestinal stromal tumors displayed low signal intensity on T1-weighted images, and intermediate to high signal intensity on T2-weighted images. Central necrosis could be seen as a high signal on T2-weighted images.

CONCLUSION: MRI is a helpful technique to define the extent of the retrorectal tumor and its relationship to the surrounding structures, and also to demonstrate possible complications so as to choose the best surgical approach.

Spinal Cord Infarction following Abdominal Surgery and Postoperative Epidural Analgaesia

Ischemic infarction is a rare cause of acute myelopathy. We report the case of a young woman admitted to Sultan Qaboos University Hospital, Oman, who developed extensive spinal cord infarction in the setting of surgical evacuation and packing of liver haematoma and post-operative epidural analgesia. She had no vascular risk factors for stroke. The vascular mechanism underlying ischemic myelopathy and the relationship to abdominal surgery and epidural analgesia are discussed.

Rapid iron loading in heart and liver in a patient with transfusion dependent thalassaemia after brief poor compliance with iron chelation therapy

Iron loading in patients with transfusion dependent thalassaemia is considered to occur primarily in the liver and, once the liver becomes saturated, other organs begin loading. We report here a splenectomised male patient who was treated for hepatitis C virus infection. Prior to starting antiviral therapy, his serum ferritin was maintained below 500 ng/ml with deferiprone monotherapy; cardiac T2* by magnetic resonance imaging was 48.8ms and hepatic T2* was 19.5ms. After twelve months of antiviral treatment during which time he was very poorly compliant with his deferoxamine chelation therapy, his ferritin had risen to 3820 ng/ml and cardiac and hepatic T2* findings were 12.7 ms and 14.5 ms respectively, indicating increased iron loading in both organs, but particularly in the heart. Fifteen months after recommencing combination chelation, his ferritin was 95 ng/ml and cardiac and hepatic T2* were 27.5 and 28.4ms respectively, indicating complete clearance of iron load in both organs. This case demonstrates that iron overload can develop rapidly and in some cases there is relatively rapid iron loading in the heart as compared to the liver.

Manic episode associated with mega cisterna magna

Mega cisterna magna is a part of "Dandy-Walker Complex" and it is characterized by the enlargement of the cisterna magna, morphologically intact vermis and cerebellar hemispheres. We report a case of manic attack in a 23-year-old man with mega cisterna magna. The patient was treated with quetiapine 1,000 mg/day and sodium valproate 1,500 mg/day and the symptoms were ameliorated within 2.5 months. In this case, mega cisterna magna and manic symptoms may be found together coincidentally or any cerebellar dysfunction due to mega cisterna magna may cause or contribute to the appearance of affective symptoms. To our knowledge, this is the first case reporting manic attack with psychotic symptoms associated with mega cisterna magna. This report suggests that any lesion in the cerebellum might contribute to the occurrences of some affective and psychotic symptoms seen in bipolar disorder.