Restricted Diffusion Pattern Research Articles

Role of MRI in distinguishing intrahepatic cholangiocarcinoma from poorly differentiated hepatocellular carcinoma

ObjectivesTo evaluate the role of MRI in the diagnosis of mass-forming intrahepatic cholangiocarcinoma (mICC), its enhancement pattern with contrast agent, and distinction from poorly differentiated hepatocellular carcinoma (pHCC).BackgroundmICC is the second most common primary hepatobiliary tumor that is increasing in incidence. Imaging characteristics in mICC differ significantly, having overlapping imaging features with pHCC. Thus, it is important to differentiate mICC from pHCC.Patients and methodsA retrospective MRI study was conducted on 15 patients with mICC and 15 patients with pHCC referred to MRI unit of the National Liver Institute, Menoufia University from June 2017 to January 2019. MRI were analyzed for tumor shape, intratumoral hemorrhage, fibrous capsule, T2 signal intensity, capsular retraction, intratumoral fat, biliary dilatation, vascular invasion, intraductal lesion, intrahepatic metastasis, restricted diffusion, and enhancement pattern after contrast injection. Associations between MRI features and tumor type were examined using the Fisher's exact and χ2 tests.ResultsLate enhancement was more common in mICC than pHCC (P < 0.001). T2 central hypointense area was more common in mICC versus HCC (P = 0.001). Capsular retraction was more common in mICC than HCC (P = 0.001). Biliary dilatation was more common in mICC than pHCC (P = 0.001). Fat component was more in pHCC than mICC (P = 0.01). Fibrous capsule was more common in pHCC than mICC (P = 0.002). Others parameters were not significant.ConclusionBiliary dilatation, central fibrosis, overlying capsular retraction, and late enhancement at 3 min with absence of fat and fibrous capsule appear to be the most important characteristics for mICC and help its differentiation from pHCC.

Radiological evaluation of deep soft tissue fibromatosis, the characteristic MR criteria on conventional and corresponding diffusion-weighted images

BackgroundTo analyze the characteristic features of deep fibromatosis on conventional and diffusion-weighted MR images.ResultThe lesions were growing along the musculoaponeurotic fascia, mostly invaded the muscles, and showed ill-defined margins, low T2 signal bands and areas, and facial tail sign. Diffusion images showed mostly high or high mixed with low signal; only 2 lesions showed a persistent low signal. The average mean and minimum ADC values were 1.41 ± 0.26 × 10−3 mm2/s and 0.79 ± 0.43 × 10−3 mm2/s respectively. Post-contrast and DWI detected synchronous lesions and extensions missed on T1 and T2 images.ConclusionThe most frequent MR features of deep fibromatosis are low T2 signal bands and areas, fascial tail sign, ill or partially defined margins, and predominant restricted diffusion pattern in addition to areas of “T2-blackout effect.” Post-contrast and DWI are more valuable in local staging of the tumor.

Does MRI diffusion help in the detection and characterization of benign and malignant hepatic focal lesions in the nonpediatric age group?

Introduction Liver MRI has been used in cases where ultrasound or computed tomography findings are equivocal. Diffusion-weighted imaging (DWI) established an important role in clinical use in the liver. DWI can potentially add useful information to conventional imaging. Objective The aim was to assess the role of DWI in the detection and characterization of hepatic focal lesions and its value to differentiate benign from malignant masses. Patients and methods The study included 40 patients, 19 women and 21 men, their ages ranged from 20 to 63 years. All patients underwent detailed MRI study of the abdomen. Diffusion study was performed with tridirectional diffusion gradients using b values 0, 500, and 1000 s/mm2 to increase the sensitivity. Apparent diffusion coefficient (ADC) maps and values were calculated for all lesions. Results In all, 20 patients were diagnosed to have benign lesions and 20 patients were diagnosed to have malignant lesions. Hemangiomas and cysts showed facilitated diffusion while adenomas show restricted diffusion pattern mimicking malignant focal lesions. On the other hand, all malignant lesions showed restricted diffusion evidenced by increased signal on increasing the b values and low signal on ADC maps. Mostly benign lesions show higher ADC values than malignant lesions. Conclusion Diffusion-weighted MRI sequence with quantitative ADC measurements should be used as an additional sequence to supplement conventional MRI protocol studies for proper characterization of focal hepatic lesions putting into consideration an overlap range.

P112 Association of Cryptococcosis and Tuberculosis in a Patient With Crohn's Disease - A Challenging Diagnosis

CASE: A 23-years-old man born in Rio de Janeiro with established ileocolonic Crohn’s disease (CD), eight years after the onset of symptoms. He started combination therapy (azathioprine and infliximab) after negative TB screening (negative PPD, normal chest x-ray). After six months, he was in clinical remission and presented with fever and headache lasting for one week. BMI was 16 kg/cm2. Laboratory findings showed an elevated ESR (90 mm/hr) and CRP level (23 mg/L), but white blood cells count was normal. Both drugs were discontinued and the patient was admitted. Cranial computed tomography (CT) was unremarkable. CT of the chest showed pleural thickening, fibro-atelectatic bands, and bronchiectasis in the upper left lobe, with calcified nodules, suggesting TB sequelae. CT of the abdomen showed splenomegaly and multiple small hypodense nodules. Abdominal MRI revealed that the lesions were isointense in T1, slightly hyperintense in T2, with a restricted-diffusion pattern, compatible with splenic abscesses. Echocardiogram was normal. HIV, EBV, CMV, HSV serology and serum latex-cryptococcus antigen test were negative. Hemoculture and urine cultures were negative. Sputum bacilloscopy and culture were also negative. Bronchoscopy with bronchoalveolar lavage fluid (BALF) showed culture and direct microscopic examination positives for cryptococcal infection. Due to the findings of splenic lesions, there was strong evidence of cryptococcal dissemination, and a lumbar puncture was performed. CSF analysis was normal, latex-cryptococcus antigen test, microscopic examination and culture were negative, excluding CNS involvement. He was discharged home with fluconazole 400 mg PO QD and his symptoms gradually subsided after 2 weeks. Three months after releasing azathioprine, it was necessary to be reintroduced due to a CD flare. After one month, he presented cough and pleuritic chest pain. Chest CT showed ground-glass opacification, and his symptoms improved with antibiotic therapy. Abdominal CT demonstrated an increase in the number and size of the spleen abscesses. A diagnostic laparoscopy with peritoneal lavage and biopsy was scheduled to investigate the etiology of splenic abscesses. However, as pleuritic chest pain and cough returned before that, he went to the emergency room where a new chest CT showed typical signs of pulmonary TB. Sputum culture confirmed the diagnosis. Hence, the abdominal findings were attributed to disseminated TB. He was discharged home with rifampin, isoniazid, pyrazinamide, and ethambutol, and will be followed up until clinical and radiologic response. This case illustrates two concomitant opportunistic infections associated with CD treatment with a clinical and radiological worsening related to an Immune Reconstitution Inflammatory Syndrome after azathioprine and infliximab withdrawal. Clinical reasoning was essential for definitive diagnosis. The possibility of two concomitant life-threatening infections with atypical manifestations in IBD patients should always be evaluated, mainly in Latin America.

Peri-ictal magnetic resonance imaging in status epilepticus: Temporal relationship and prognostic value in 60 patients

Purpose. Magnetic resonance imaging (MRI) changes associated with status epilepticus (SE) have been described in recent studies. Our aim was to evaluate the diagnosis and prognosis of the peri-ictal MRI changes detected in SE patients.Method. All adults diagnosed with SE and examined by MRI within 240 h after SE onset were enrolled (2011–2017). Demographic, clinical and electroencephalography data, and functional status at admission and discharge were collected. MRI findings were recorded and relationships between clinical and MRI data, and between these data and functional outcome were analyzed.Results. Sixty patients included, 50% women, mean age 57.5 years. Median duration of SE was 51.46 h and median time from SE onset to MRI was 86.5 h. Of the total, 41.7% had a restricted diffusion pattern on diffusion-weighted imaging (DWI) and 63.3% had hyperintensities suggestive of edema on T2-weighted (T2WI)/FLAIR sequences. The factors independently associated with T2WI hyperintensities were the presence of acute cerebral lesions (p = 0.023), baseline STESS (p = 0.007), and MRI performed within 84 h (p = 0.007). Variables independently associated with diffusion restriction were a potentially fatal cause (p = 0.020), SE duration >24 h (p = 0.022), and MRI performed within the first 84 h (p = 0.045). In patients undergoing MRI within 84 h, the DWI and T2WI abnormalities were both highly associated with an unfavorable outcome.Conclusions. Characteristic signal changes on DWI and T2WI sequences were seen in approximately half our SE patients undergoing early (<84 h) brain MRI studies, and were independently related to the patients’ functional status at discharge.

Purely endoscopic supracerebellar infratentorial approach for epidermoid cyst in third ventricle

Introducción: El Quiste Epidermoide como tumor de la región pineal es una patología infrecuente y poco descripta. Su prevalencia en el 3er ventrículo es de 0,0042% de los tumores primarios intracraneales. Para lograr la exeresis macroscópica total se utilizó el abordaje Supracerebeloso Infratentorial con Endoscopio rígido de Base de Cráneo, técnica descripta para abordaje de lesiones de la región pineal. El Objetivo del Trabajo es la presentación de la técnica quirúrgica del abordaje, con la resolución de la patología infrecuente que se presenta.Materiales y métodos: Paciente de 16 años de edad con antecedentes de DBT insípida y cefaleas crónicas intermitentes (m-RS 1). RMN de encéfalo evidencia lesión ocupante de espacio hiperintensa T2 e hipointensa en T1 con realce periférico y restricción en la difusión. Presenta refuerzo a nivel del tallo hipofisario. Se plantea diagnóstico de tumor germinal. Marcadores en LCR negativos. Se decide realizar abordaje puramente endoscópico de la región para toma de muestra. Congelación determina quiste epidermoide y se procede a realizar exeresis macroscópica total.Resultados: Se realizó exeresis macroscópica total de quiste de epidermoide en tercer ventrículo con abordaje supracerebeloso infratentorial a través de endoscópico rígido de base de cráneo, en paciente de 16 años, cursando postoperatorio tardío sin secuelas y mejoría sintomática con persistencia de DBT insípida (m-RS 1).Conclusión: El abordaje puramente endoscópico supracerebeloso infratentorial es una opción segura para el tratamiento quirúrgico de lesiones en el tercer ventrículo, en este caso, un quiste epidermoide.

Can diffusion-weighted imaging be used as a tool to predict seizures in patients with PLEDS?

It is unclear which patients with PLEDs will have associated seizures and therefore will need to be treated aggressively with antiepileptic medications. We present a prospective observational study of ten consecutive non-anoxic patients with PLEDs based on continuous 24-hour EEG monitoring. According to the EEG, five of the patients had seizures associated with PLEDs and five had PLEDs but no seizures. The aetiology included: neoplasm (n=1), cortical dysplasia (n=1), acute head trauma (n=1), encephalomalacia related to healed abscess (n=1), intra-parenchymal haemorrhage (n=1), and no structural lesion (n=5). All patients underwent brain MRI using diffusion-weighted imaging (DWI). We found that the five patients who had seizures with PLEDs on continuous EEG had restricted diffusion on DWI. In contrast, the five patients who had PLEDs but no seizures on continuous EEG did not show a restricted diffusion pattern on DWI. We will continue to prospectively assess DWI findings in this group of patients and encourage other centres to also review similar data. If our observation is replicated, this would indicate that restricted diffusion on brain MRI may be a useful marker to identify patients with PLEDs on their EEG who are likely to have associated seizures.

Adrenoleukodystrophy: Diffusion MRI findings

An 8-year-old boy with laboratory evidence of adrenal insufficiency, and an established diagnosis of X-linked adrenoleukodystrophy was referred to our institution for a follow-up magnetic resonance imaging (MRI) examination. Besides T1 and T2-weighted sequences, a diffusion MRI protocol was added. The “trace” sequence, a single-shot, spin-echo, echo-planar imaging sequence was used, which averages the data from the three (x, y, and z) gradients and which provides automatically generated apparent diffusion coefficient (ADC) maps. The acquisition time was 22 sec with TR = 5700 msec, and TE = 139 msec, and slice thickness was 5 mm. On diffusion MRI b = 1000 sec/mm images revealed high-signal changes similar to that seen in cases of restricted diffusion pattern (Fig. 1a). However, the ADC maps revealed that an elevated diffusion pattern was present in the necrotic regions (2.06 and 1.60 × 10−3 mm/sec). The ADC value of the central necrotic zone was higher (2.06× 10−3 mm/sec) compared to that of the peripheral necrotic zone (1.60 × 10−3 mm/sec), and that of the intermediate zone of active demyelination was lower (1.14 × 10−3 mm/sec) (Fig. 1b). These values were higher than the ADC values of the normal regions of the brain parenchyma.

Anterior Choroidal Artery Territory Stroke in Young Patient

Introduction: Stroke incidence in young patients is about 10 cases in 100.000, according to several European studies. In this age group arterial dissection is one of the main pathological mechanisms involved. The internal carotid’s artery (ICA) main supraclinoid branch is the anterior choroidal artery (AChA). The occurrence of infarction in its territory due to internal carotid dissection is considered to be a rare event and may have different clinical presentations due to anatomical variability. Clinical case: A 31-year-old male patient, without any known cardiovascular risk factors or chronic medication, presented with acute onset of stabbing right sided headache while practicing football. Visual disturbances and hemiparesis with hypesthesia of his left arm were also mentioned. On admission left homonymous hemianopsia, left hemiparesis and left extensor plantar reflex were present. Brain magnetic resonance showed hyperintensity of T2 and FLAIR signals and restricted diffusion pattern suggested acute/subacute infarctions in the thalamic and subcapsular area, corpus callosum, splenium and subcortical parietal right region. Magnetic resonance angiography (MRA) of the brain showed reduction of the right ICA’s caliber, mainly of its supraclinoid segment in which a marked irregular stenosis was visualized, suggestive of arterial dissection. This stenotic segment included the origin of the AChA and of the posterior communicating cerebral artery with an exchange in their territories. Lumbar puncture results were normal as were analytical investigations which included CBC, sedimentation rate, syphilis serology and immunologic and prothrombotic screen. There were no phenotype characteristics suggestive of connective tissue disease. Conclusion: Trauma seems to be the most probable lesion mechanism for the occurrence of intracranial carotid’s dissection in this particular case, as the patient was practicing vigorous sports at time of onset. In view of great anatomic variability and multiple anatomical sites supplied by the AChA its occlusion will induce a wide range of clinical manifestations.

Diffusion-weighted imaging in acute demyelinating myelopathy

Diffusion-weighted imaging (DWI) has become a reference MRI technique for the evaluation of neurological disorders. Few publications have investigated the application of DWI for inflammatory demyelinating lesions. The purpose of the study was to describe diffusion-weighted imaging characteristics of acute, spinal demyelinating lesions. Six consecutive patients (two males, four females; aged 28-64years) with acute spinal cord demyelinating lesions were studied in a prospective case series design from June 2009 to October 2010. We performed magnetic resonance imaging studies from 2 to 14days from symptom onset on the patients with relapsing remitting multiple sclerosis (n = 3) or clinically isolated syndrome (n = 3). Main outcome measures were diffusion-weighted imaging and apparent diffusion coefficient pattern (ADC) of acute spinal cord demyelinating lesions. All spinal lesions showed a restricted diffusion pattern (DWI+/ADC-) with a 24% median ADC signal decrease. A good correlation between clinical presentation and lesion site was observed. Acute demyelinating spinal cord lesions show a uniform restricted diffusion pattern. Clinicians and neuro-radiologists should be aware that this pattern is not necessarily confirmatory for an ischaemic aetiology.

L-2 Hydroxyglutaric Aciduria: Magnetization Transfer Contrast and Diffusion Weighted Magnetic Resonance Imaging Findings

We describe the case of a 13-year-old male with ù aciduria. Conventional magnetic resonance imaging and diffusion weighted imaging disclosed some previously unreported findings. In particular, we observed an almost total sparing of early myelinated regions, and a restricted diffusion pattern in the dentate nuclei. Magnetization transfer contrast showed a normal range of values in early myelinated regions, and revealed abnormal values in the subcortical temporal white matter, internal capsule and globi palladi.

Diffusion magnetic resonance imaging patterns in metabolic and toxic brain disorders

To evaluate metabolic and toxic brain disorders that manifest with restricted, elevated, or both restricted and elevated diffusion patterns on diffusion magnetic resonance imaging (MRI). Echo-planar diffusion MRI examinations were obtained in 34 pediatric patients with metabolic and toxic brain disorders proved by appropriate laboratory studies. The MRI unit operated at 1.5 T with a gradient strength of 30 mT/ meter, and a rise time of 600 micros. b=1000s/mm2 images and apparent diffusion coefficient (ADC) maps with ADC values were studied. Three patterns were observed: 1. A restricted diffusion pattern (high signal on b = 1000 s/mm2 images and low ADC values); 2. an elevated diffusion pattern (normal signal on b = 1000s/mm2 images and high ADC values); and 3. a mixed pattern (coexistent restricted and increased diffusion patterns in the same patient). Disorders manifesting with a restricted diffusion pattern included metachromatic leukodystrophy (n = 2), phenylketonuria (n = 3), maple syrup urine disease (intermediate form) (n = 1), infantile neuroaxonal dystrophy (n = 1), Leigh (n = 2), Wilson (n = 3), and Canavan disease (n = 1). Disorders with an elevated diffusion pattern included phenylketonuria (n = 1), adrenoleukodystrophy (n = 1), merosin-deficient congenital muscular dystrophy (n = 2), mucopolysaccharidosis (n = 2), Lowe syndrome (n = 1), Leigh (n = 2), Alexander (n = 1), Pelizaeus-Merzbacher (n = 1), and Wilson (n = 3) disease. Disorders with a mixed pattern included L-2 hydroxyglutaric aciduria (n = 2), non-ketotic hyperglycinemia (n = 1), infantile neuroaxonal dystrophy (n =2), maple syrup urine disease (n = 1), and Leigh (n = 1) disease. The findings suggested that the three different diffusion patterns reflect the histopathological changes associated with the disorders and different stages of a particular disorder. It is likely that the restricted diffusion pattern corresponds to abnormalities related to myelin, and the elevated diffusion pattern to disintegration of the tissue. The mixed pattern has contributions from both myelin abnormalities related to myelin disintegration of the tissue.

Metachromatic Leukodystrophy. Diffusion MR imaging and proton MR spectroscopy

Metachromatic leukodystrophy is characterized by dysmyelination caused by a deficiency of arylsulfatase-A. In a 17-month-old boy with metachromatic leukodystrophy, an echo-planar diffusion MR sequence revealed a restricted diffusion pattern in the deep white matter, manifested by high-signal on b=1000 s/mm2 images, and low ADC values (0.56 x 10(-3) mm2/s). Proton MR spectroscopy revealed a marked decrease in choline, a metabolite related to myelin turnover. These observations consisting of a restricted diffusion pattern on diffusion MR imaging, and decreased choline peaks on proton spectroscopy, likely represented dysmyelination in metachromatic leukodystrophy.

ADEM: diffusion MRI findings

Acute disseminated encephalomyelitis (ADEM) usually reveals patchy demyelinated lesions with high signal on T2-weighted sequences. Diffusion MRI in a 10-year-old patient with ADEM demonstrated two distinct lesion patterns occurring simultaneously in the cerebral white matter. These were a restricted diffusion pattern (high-signal on b=1000 mm 2/s images with low apparent diffusion coefficient (ADC) values, and a demyelinating pattern (negative b=1000 mm 2/s images with high ADC values). The patient responded well to intravenous methylprednisolone therapy. Further studies are required for detailed evaluation of such patterns in ADEM, and their clinical relevance, and for discrimination from other inflammatory encephalopathies.

Diffusion MRI findings in phenylketonuria

Two patients with phenylketonuria were studied who were under dietary control since infancy, and who were mentally normal. Diffusion MRI was obtained using a spin-echo, echo-planar sequence with a gradient strength of 30 mT/m at 1.5 T. A trace sequence (TR=5700 ms, and TE=139 ms) was used, acquired in 22 s. Heavily diffusion-weighted (b=1000 mm(2)/s) images, and the apparent diffusion coefficient (ADC) values from automatically generated ADC maps were studied. There were two different patterns in these two patients, restricted and increased diffusion patterns. Restricted diffusion pattern consisted of high-signal on b=1000 s/mm(2) images with low ADC values ranging from 0.46 to 0.57 x 10(-3 )mm2/s. Increased diffusion pattern consisted of normal b=1000 s/mm(2 )images with high ADC values ranging from 1.37 to 1.63 x 10(-3 )mm2/s. It is likely that these values reflected presence of two different histopathological changes in phenylketonuria or reflected different stages of the same disease.