Virtual contrast enhancement for CT scans of abdomen and pelvis.

Contrast agents are commonly used to highlight blood vessels, organs, and other structures in magnetic resonance imaging (MRI) and computed tomography (CT) scans. However, these agents may cause allergic reactions or nephrotoxicity, limiting their use in patients with kidney dysfunctions. In this paper, we propose a generative adversarial network (GAN) based framework to automatically synthesize contrast-enhanced CTs directly from the non-contrast CTs in the abdomen and pelvis region. The respiratory and peristaltic motion can affect the pixel-level mapping of contrast-enhanced learning, which makes this task more challenging than other body parts. A perceptual loss is introduced to compare high-level semantic differences of the enhancement areas between the virtual contrast-enhanced and actual contrast-enhanced CT images. Furthermore, to accurately synthesize the intensity details as well as remain texture structures of CT images, a dual-path training schema is proposed to learn the texture and structure features simultaneously. Experiment results on three contrast phases (i.e. arterial, portal, and delayed phase) show the potential to synthesize virtual contrast-enhanced CTs directly from non-contrast CTs of the abdomen and pelvis for clinical evaluation.

Eliminating rib shadows in chest radiographic images providing diagnostic assistance.

A major difficulty with chest radiographic analysis is the invisibility of abnormalities caused by the superimposition of normal anatomical structures, such as ribs, over the main tissue to be examined. Suppressing the ribs with no information loss about the original tissue would therefore be helpful during manual identification or computer-aided detection of nodules on a chest radiographic image. In this study, we introduce a two-step algorithm for eliminating rib shadows in chest radiographic images. The algorithm first delineates the ribs using a novel hybrid self-template approach and then suppresses these delineated ribs using an unsupervised regression model that takes into account the change in proximal thickness (depth) of bone in the vertical axis. The performance of the system is evaluated using a benchmark set of real chest radiographic images. The experimental results determine that proposed method for rib delineation can provide higher accuracy than existing methods. The knowledge of rib delineation can remarkably improve the nodule detection performance of a current computer-aided diagnosis (CAD) system. It is also shown that the rib suppression algorithm can increase the nodule visibility by eliminating rib shadows while mostly preserving the nodule intensity.

Sonoelastographic qualitative analysis for management of salivary gland masses.

OBJECTIVES: Our aim was to investigate whether the use of a qualitative elasticity scoring method by sonoelastography is beneficial for management of salivary gland masses. METHODS: Thirty-six patients with salivary gland masses (30 parotid and 6 sub-mandibular) were prospectively included in this study. For each lesion, B-mode sonographic and sonoelastographic images were obtained. Elasticity scores were determined by a 4-point scoring method. Differences among scores for benign and malignant masses were assessed by the Mann-Whitney U test. Qualitative variables were compared by the Pearson χ² test. The findings were compared with histopathologic diagnoses. RESULTS: The score values of 28 benign masses ranged from 1 to 4, whereas the values of 8 malignant masses ranged from 2 to 4. The mean scores ± SD were 2.25 ± 0.92 for benign lesions and 3.0 ± 0.75 for malignant lesions (P < .05). When we considered scores 1 and 2 as benign and scores 3 and 4 as malignant, 10 false-positive results were determined by the 4-point scoring method, and 64.2% of benign masses were diagnosed. CONCLUSIONS: Sonoelastography might be regarded as another sonographic parameter for management of salivary gland masses in terms of detecting benign masses.

MR cholangiopancreatography with T2-weighted prospective acquisition correction turbo spin-echo sequence of the biliary anatomy of potential living liver transplant donors.

OBJECTIVE: The objective of our study was to evaluate the ability of a respiratory navigator-triggered T2-weighted turbo spin-echo (TSE) sequence with a prospective acquisition correction (PACE) technique for MR cholangiopancreatography (MRCP) to depict the biliary anatomy of living donor liver transplantation (LDLT) donors. SUBJECTS AND METHODS: Forty potential LDLT donors who ranged in age from 19 to 54 years were prospectively evaluated with preoperative MRCP. MRCP was performed with a 1.5-T magnetic field using T2-weighted PACE TSE sequence. MRCP source data sets were processed with maximum-intensity-projection (MIP) and shaded surface display (SSD) algorithms. Findings were compared with intraoperative cholangiography. Biliary anatomy was classified according to the classification proposed by Huang and colleagues. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRCP for the detection of aberrant biliary anatomy were calculated. RESULTS: Intraoperative cholangiography and biliary exploration revealed that 27 donor candidates (67.5%) had conventional and 13 (32.5%) had aberrant biliary anatomy. Two donors (5%) had type B biliary anatomy; eight donors (20%), type C; two donors (5%), type D; and one donor (2.5%), unclassified. The sensitivity of MRCP source data sets in differentiating aberrant biliary anatomies from nonaberrant ones was 100%, the specificity was 88.9%, and the accuracy was 92.5%. PPV and NPV were 81.3% and 100%, respectively. The sensitivity of MIP images in differentiating aberrant biliary anatomies was 100%, the specificity was 88.9%, and the accuracy was 92.5%. PPV and NPV were 81.3% and 100%, respectively. The sensitivity, specificity, accuracy, PPV, and NPV of the SSD images in detecting aberrant biliary anatomies were 100%, 77.8%, 85%, 68.4%, and 100%, respectively. CONCLUSION: Preoperative MRCP using a respiratory navigator-triggered T2-weighted TSE sequence with a PACE technique accurately depicts the biliary anatomy in LDLT donors and may guide intraoperative management of the biliary tract.

Hypernatraemic dehydration in a neonate: brain MRI findings.

Severe hypernatremic dehydration can cause serious neurological complications in neonates. The most significant problems include brain oedema, intracranial haemorrhage, sinus thrombosis, haemorrhagic infarcts and permanent brain damage. The symptoms of many of these complications are similar. With respect to brain MRI findings in hypernatremic neonates, this is a report that describes linear lesions that represent intracranial haemorrhage at the grey-white matter junction. These MRI findings may be helpful for diagnosing hypernatremic dehydration, and for ruling out differential diagnoses for complications of this disorder.

Abnormal diffusion-weighted imaging findings in an adult patient with acute cerebellitis presenting with a normal magnetic resonance imaging.

Acute cerebellitis is an unusual central nervous system complication of infectious disease often due to viral etiology. Diagnosis is aided by neuroimaging studies, actually by magnetic resonance imaging in the first place, which shows increased signal intensity on T2-weighted images. However, conventional magnetic resonance imaging may be unrevealing in some of the cases, and additional workup such as single photon emission computed tomography and diffusion-weighted imaging may be required. We present a case of acute cerebellitis in a 35-year-old woman diagnosed by diffusion-weighted imaging.

Postpartum sacral stress fracture: an unusual case of low-back and buttock pain.

Low-back and buttock pain is a common complaint during pregnancy and the postpartum period and is usually attributable to mechanical lesions of the pelvis. Sacral stress fractures are unusual but important causes that should be considered in differential diagnosis. To date, only eight postpartum sacral stress fractures have been reported in the literature. A 32-yr-old woman presented with low-back and right buttock pain that started 15 days after uneventful cesarean section delivery. Imaging studies revealed a right sacral stress fracture. Lumbar spine and femoral neck bone mineral density were normal and, except for pregnancy and lactation, no risk factors for osteoporosis were identified. There was no history of trauma, excessive weight gain, strenuous physical activity, or contribution of mechanical factors. The question remains whether this is an insufficiency fracture or a fatigue fracture. Clinicians should consider sacral fracture during pregnancy and the postpartum period as a diagnostic possibility in patients with low-back and/or buttock pain.

Posterior leukoencephalopathy syndrome in children and adolescents.

Posterior leukoencephalopathy syndrome is a recently identified clinical and radiologic entity. The characteristic radiologic findings are bilateral gray and white matter edema in the posterior regions of the cerebral hemispheres. This article reports clinical and radiologic findings in 10 consecutive episodes of posterior leukoencephalopathy syndrome that were diagnosed in 9 children and adolescents. The causes were immunosuppressive therapy in 7 patients and a combination of renal failure and hypertension in 3. The most common presenting symptoms were seizure and altered consciousness; others included headache, sixth nerve palsy, and cortical blindness. Imaging demonstrated abnormalities in the parietal and occipital lobes in all 10 episodes. The signs and symptoms resolved after immunosuppressive agents were reduced or discontinued, or after uremia and hypertension were corrected. Four patients underwent follow-up cranial imaging, and the images showed nearly complete or complete resolution. The syndrome was clinically reversible in all patients.

Brain abscess associated with isolated left superior vena cava draining into the left atrium in the absence of coronary sinus and atrial septal defect.

A previously healthy 12-year-old girl presented with severe headache for 2 weeks. On physical examination, there was finger clubbing without apparent cyanosis. Neurological examination revealed only papiledema without focal neurologic signs. Cerebral magnetic resonance imaging showed the characteristic features of brain abscess in the left frontal lobe. Cardiologic workup to exclude a right-to-left shunt showed an abnormality of the systemic venous drainage: presence of isolated left superior vena cava draining into the left atrium in the absence of coronary sinus and atrial septal defect. This anomaly is rare, because only a few other cases have been reported.

Body height estimation based on dimensions of sacral and coccygeal vertebrae.

This study is to evaluate whether it is possible to predict living stature from sacral and coccygeal vertebral dimensions. Individual vertebral body heights, sacral height (SH), and sacrococcygeal height (SCH) were recorded from the magnetic resonance images of 42 adult males. Sum of the heights of five sacral vertebrae (sigmaS), the first four coccygeal vertebrae (sigmaC), and the total height of the sacral and the first four coccygeal vertebrae together (sigmaSC) were also recorded. Linear regression equations for stature estimation were produced using the above mentioned variables. The regression equations were constructed and tested by using jack-knife procedure. Statistical analyses indicated that the combined variables (SH, SCH, sigmaS, sigmaC, sigmaSC) were more accurate predictors of stature than the heights of individual vertebrae. The results of the study pointed out that the equations derived from sacrococcygeal dimensions perform somewhat better than ones based on foot and head variables, but worse than those based on long-bone length. As a conclusion, the dimensions of sacral and coccygeal vertebrae could be used for stature estimation when long bones are not available.

MRI evaluation of cranial bone marrow signal intensity and thickness in chronic anemia.

BACKGROUND AND PURPOSE: The aim is to assess the magnetic resonance imaging (MRI) findings for cranial bone marrow (CBM) signal intensity and thickness in patients with chronic anemia and compared these with findings in healthy subjects. We also investigated the relationships between CBM changes and age, type of anemia (hemolytic versus non-hemolytic), and severity of anemia. METHODS: We quantitatively evaluated CBM signal intensity and thickness on images from 40 patients with chronic anemia (20 with congenital hemolytic anemia (HA) and 20 with acquired anemia) and compared these to findings in 28 healthy subjects. The intensity of CBM relative to scalp, white matter (WM), gray matter (GM), and muscle intensity was also investigated in patients and subjects in the control group. The sensitivity and specificity of CBM hypointense to GM and CBM hypointense to WM as markers of anemia were evaluated. Relationships between age and CBM thickness/intensity, and between anemia severity (hemoglobin (Hb) level) and CBM thickness/intensity were evaluated. RESULTS: Cranial bone marrow signal intensity was lower in the chronic anemia patients than in the controls (P<0.001). In the control group, CBM intensity was higher than GM intensity, whereas the opposite was true in the patient group. The finding of CBM hypointense to GM was 85% sensitive and 67% specific as a marker of anemia. The corresponding statistics for CBM hypointense to WM were 90 and 46%. The patients had thicker CBM than the controls (temporal, P<0.05; parietal, P<0.005). The subgroup with hemolytic anemia had thicker parietal CBM than the subgroup with non-hemolytic anemia (NHA) (P<0.05) and exhibited thicker temporal and parietal CBM than the controls (temporal, P<0.05; parietal, P<0.001). The CBM thicknesses in the non-hemolytic anemia subgroup were similar to control values (P>0.05 for both). There were no correlations between age and CBM intensity or thickness, or between anemia severity and CBM intensity or thickness. CONCLUSION: Patients with chronic anemia exhibit lower CBM signal intensity on MRI than healthy subjects. Patients with hemolytic anemia have thicker CBM than patients with non-hemolytic anemia or healthy individuals. Decreased CBM intensity may indicate that the patient has anemia, and increased CBM thickness may specifically point to hemolytic anemia. These MRI findings may signal the need for further evaluation for the clinician.

[Brain MR perfusion and MR spectroscopy in differentiation of radiation necrosis from tumor recurrence (case report)]. / Radyasyon nekrozu-tümör rekürensi ayriminda MR perfüzyon ve MR spektroskopi.

It is not always possible to differentiate tumor recurrence from radiation necrosis using conventional MR images. In this report we present a case of pathologically proven radiation necrosis which appeared as nodular contrast enhancement on conventional MR images in a patient who was surgically treated for grade II astrocytoma 5 years ago. There were decreased choline, creatine and N-acetyl aspartate peaks and significantly increased lipid peak on multivoxel H1-MR spectroscopy while there was no significant perfusion increase on MR perfusion. These findings suggested changes secondary to radiation necrosis.

Bilateral double by testis: evaluation magnetic resonance imaging.

Bilateral double testis, a varient of polyorchidism, is a rare malformation of which six cases have been reported in the published literature. Magnetic resonance imaging was used in the presented case to confirm the diagnosis without surgical exploration.

Primary hydatid cyst in the anterior thigh: Sonographic findings.

Hydatid cysts rarely involve the musculoskeletal system. We present the case of a 23-year-old man with a primary hydatid cyst between the femur and the quadriceps muscle in his left thigh. No cysts were located in the adjacent femur or quadriceps muscle. Cyst resection with sparing of the surrounding muscles, combined with anthelmintic therapy, was curative. In regions where hydatidosis is endemic, hydatid cysts should be included in the differential diagnosis of any unusual soft-tissue swelling.

Osmotic demyelination syndrome in end-stage renal disease after recent hemodialysis: MRI of the brain.

OBJECTIVE: Osmotic demyelination syndrome has been reported in patients with end-stage renal disease, but the specific MRI findings in this patient group have not been documented in detail. Our aims were to present the brain MRI findings during an episode after hemodialysis and at follow-up, and to identify possible factors that may contribute to lesion development. MATERIALS AND METHODS: Seventeen patients with osmotic demyelination syndrome who had undergone hemodialysis at least once and had brain MRI examinations were retrospectively reviewed. Neurologic and MRI examinations were performed during a clinical episode. Serum levels of sodium, creatinine, blood urea nitrogen, and glucose were assessed, and serum osmolality and the ratio of blood urea nitrogen to creatinine (BUN:Cr) were calculated. Follow-up MRI was performed in nine cases. Laboratory and imaging findings were evaluated. RESULTS: An altered level of consciousness and convulsions were the most common neurologic symptoms. The pons was involved in 11 patients (65%) and extrapontine sites in 12 (71%). Four patients had dysequilibrium syndrome. Follow-up MRI showed complete resolution in six patients and lesion reduction in three within a short time. The most common biochemical changes at the time of MRI were hyponatremia and low BUN:Cr in the blood. Only one patient showed rapid correction of hyponatremia and a rapid change in osmolality during the acute stage. CONCLUSION: In patients who develop osmotic demyelination syndrome after hemodialysis, the lesions may involve the pons or the pons and extrapontine sites. Most lesions that were followed up resolved rapidly and almost completely, favoring transient edema rather than demyelination. Blood chemistries suggested underlying changes in osmolality, particularly as a result of urea shift from the extracellular fluid.

Central pontine myelinolysis secondary to cytomegalovirus hepatitis in a 10-month-old child.

We present a 10-month-old child with central pontine myelinolysis (CPM) secondary to chronic active hepatitis due to cytomegalovirus (CMV) infection. A total of 35 paediatric cases of pontine and/or extrapontine myelinolysis are reported and, to our knowledge, CPM secondary to CMV hepatitis in an infant has not been previously reported. The MRI findings are highlighted.

Cerebellar vermis hypoplasia in a patient with Bardet-Biedl syndrome.

Laurence-Moon-Bardet-Biedl syndome is an autosomal recessive condition characterized by retinal dystrophy, obesity, mental retardation, distal limb anomaly, hypogonadism, and renal dysfunction. The symptoms vary among families and even among affected siblings. Certain clinical signs have been used to identify subgroups of patients with this complex condition. Laurence-Moon syndrome as a distinct entity is rare and features paraplegia in the absence of polydactyly or obesity. Bardet-Biedl syndrome is characterized by distal limb anomaly, obesity, and renal involvement, but neurologic symptoms are very unusual. We report a patient exhibiting characteristic features of Bardet-Biedl syndrome in addition to cerebellar vermis hypoplasia and mega cisterna magna.