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At least 991 records · Page 55Linked to original sources
PubMed1997

Fast fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging of the brain: a comparison of multi-shot echo-planar and fast spin-echo techniques.

PURPOSE: To evaluate fast spin-echo and multi-shot echo-planar fluid-attenuated inversion recovery (FLAIR) sequences in paediatric brain imaging. MATERIALS AND METHODS: Matched images from 32 patients with suspected tumour or white matter disease were independently evaluated by two paediatric neuroradiologists. The observer preferences for image quality and lesion detection were analysed for differences between fast spin-echo FLAIR and multi-shot echo-planar FLAIR. Diagnostic quality was compared with that of fast spin-echo T2-weighted images. RESULTS: Images of a diagnostic quality equivalent to that of fast spin-echo T2-weighted images were achieved with both FLAIR techniques. Grey and white matter differentiation and cerebrospinal fluid (CSF) nulling were significantly better on fast spin-echo FLAIR sequences. CSF flow artefact was reduced on multi-shot echo-planar FLAIR. There was no difference in lesion detection. Fast spin-echo FLAIR images were visually preferred at the expense of longer imaging time. CONCLUSION: Fast FLAIR techniques are complementary to fast spin-echo T2-weighted sequences in imaging of the paediatric brain. We find that the fast spin-echo FLAIR sequence is preferable to the multi-shot echo-planar technique.

Brain↗
PubMed1999

MRI evaluation of multifidus muscles in adolescent idiopathic scoliosis.

BACKGROUND: The role of the multifidus muscles in the initiation and progression of curve in adolescent idiopathic scoliosis is not fully understood and controversy exists as to the side of the abnormality. OBJECTIVE: To evaluate on MRI the multifidus muscles at the apex of the major curve in adolescent idiopathic scoliosis to ascertain if the multifidus muscles on the convex or concave side are abnormal and the relationship to curve severity. MATERIALS AND METHODS: Forty-six patients with adolescent idiopathic scoliosis, separated into two groups, were studied using a 1.5-T MR scanner with the synergy spine coil, employing a modified STIR (short tau inversion recovery) axial sequence obtained at the apex of the major scoliotic curve. RESULTS: No hyperintense signal change was demonstrated in the convex side multifidus muscles in any patient. In group I, 16 of 18 patients with severe or rapidly progressive curve showed increase in signal intensity in the multifidus muscle on the concave side of the apex of the curve. In group II, of the 15 patients with mild curve (Cobb angle 10-30 degrees), 4 had increased signal intensity in the multifidus muscle on the concave side; of the 13 with more severe curve (Cobb angle greater than 30 degrees), 10 had increase in multifidus signal intensity on the concave side. CONCLUSIONS: The concave-side multifidus muscle at the apex of a scoliotic curve was morphologically abnormal. A significant association between abnormal signal change and curve severity was also established.

Adolescent↗
PubMed1999

Potential utility of MRI in the evaluation of children at risk of renal scarring.

BACKGROUND: Gadolinium-enhanced MRI has recently been employed in the diagnosis of acute pyelonephritis. Its potential utility in the diagnosis of renal scars in children is unknown. Objective. To evaluate the potential utility of MRI using fat-saturated T1-weighted (T1-W) and post-gadolinium, short-tau inversion-recovery (STIR) sequences in detecting renal scarring by comparison with technetium dimercaptosuccinic acid ((99 m)Tc-DMSA) renal scintigraphy in children at risk of renal scarring. MATERIALS AND METHODS: A group of 24 children with spina bifida and neurogenic bladder or anorectal anomaly was studied. No patient had a history of acute pyelonephritis. Documented urinary tract infection (UTI) was present in 10 children (42 %). The remaining 14 (58 %) children had a history of asymptomatic bacteriuria. None had clinical signs or symptoms of acute UTI at the time of the study. (99 m)Tc-DMSA and MRI were performed to detect renal scarring. (99 m)Tc-DMSA scans were supplemented with pinhole imaging. MRI of the kidneys employed a fat-saturated T1-W sequence and a post-gadolinium STIR sequence employing a short echo time. RESULTS: Of the kidneys studied, 33 % (n = 16) had evidence of a renal parenchymal defect suggestive of scarring on (99 m)Tc-DMSA. The concordance in the detection of a scarred kidney by post-gadolinium STIR sequence and (99 m)Tc-DMSA is 94 %; that by fat-saturated T1-W sequence and (99 m)Tc-DMSA is 82 %; that by both sequences (positive result on either sequence) and (99 m)Tc-DMSA is 100 %. Using (99 m)Tc-DMSA as the gold standard, MRI had a sensitivity of 100 % and a specificity of 78 % in the diagnosis of a scarred kidney. The concordance in the detection of a scarred zone by post-gadolinium STIR sequence and (99 m)Tc-DMSA is 68 %; that by fat-saturated T1-W sequence and DMSA is 44 %; that by both sequences (positive result on either sequence) and (99 m)Tc-DMSA is 84 %. MRI had a sensitivity of 84 % and a specificity of 86 % in the diagnosis of a scarred zone, using (99 m)Tc-DMSA as the gold standard. CONCLUSION: The detection rate for renal scarring on MRI using the fat-saturated T1-W and post-gadolinium STIR sequences is comparable to planar (99 m)Tc-DMSA. MRI is of potential utility in the evaluation of children at risk of renal scarring.

Anal Canal↗
PubMed2005

(39)K nuclear magnetic resonance and a mathematical model of K(+) transport in human erythrocytes.

(39)K nuclear magnetic resonance was used to measure the efflux of K(+) from suspensions of human erythrocytes [red blood cells (RBCs)], that occurred in response to the calcium ionophore, A23187 and calcium ions; the latter activate the Gárdos channel. Signals from the intra- and extracellular populations of (39)K(+) were selected on the basis of their longitudinal relaxation times, T (1), by using an inversion- recovery pulse sequence with the mixing time, tau(1), chosen to null one or other of the signals. Changes in RBC volume consequent upon efflux of the ions also changed the T (1) values so a new theory was implemented to obviate a potential artefact in the data analysis. The velocity of the K(+) efflux mediated by the Gárdos channel was 1.19+/-0.40 mmol (L RBC)(-1) min(-1) at 37 degrees C.

Cations, Monovalent↗
PubMed2004

Compositional analysis of muscle in boys with Duchenne muscular dystrophy using MR imaging.

OBJECTIVE: Boys with Duchenne muscular dystrophy (DMD) present by age 5 years with weakness and, untreated, stop walking unaided by age 10 or 11 years. We used magnetic resonance (MR) imaging to study age-related changes in the composition and distribution of diseased muscles. DESIGN AND PATIENTS: Eleven boys (mean 7.1+/-1.6 years) with DMD underwent clinical and MR examinations. Quantitative muscle strength and timed functional testing was performed. Thigh muscles were scanned at three levels (hip, mid-thigh, and knee) using T1-weighted spin echo and short-tau inversion recovery (STIR) sequences. Outcome measures included intramuscular fatty infiltration, intermuscle fat deposition, edema, and muscle size. RESULTS: Ten boys completed the study. Older boys demonstrated more prominent fatty infiltration of muscles. Fatty infiltration occurred in a characteristic pattern with the gluteus and adductor magnus muscles most commonly involved and the gracilis most commonly spared. Similarly, patchy increases in free water content suggested a pattern of intramuscular edema or inflammation. Atrophy occurred in muscles heavily infiltrated with fat, and true hypertrophy selectively occurred in those that were spared. CONCLUSIONS: While fibrofatty changes have been described in DMD, this study further defines differential involvement and additionally suggests widespread edema or inflammation. Improved imaging techniques to quantify the degree and distribution of these changes may provide a basis for exploring mechanisms of action of medications and perhaps another means for selecting treatment regimens and monitoring their effects.

Adipose Tissue↗
PubMed2000

A pilot study using magnetic resonance imaging to determine the pattern of muscle group recruitment by rowers with different levels of experience.

OBJECTIVE: To determine whether it was possible using magnetic resonance imaging (MRI) to define the pattern of muscle recruitment in a specific sport (rowing) and to see whether there were differences in this pattern between athletes of different experience. DESIGN AND METHOD: It has been shown that during vigorous exercise the water content of muscle increases transiently. This can be observed using MRI, where the prolonged T2 relaxation time of muscle can be demonstrated. In this study we have exploited the increase in signal seen in exercised muscle on short TI inversion recovery (STIR) sequences, to show how rowers of different experience use different muscle groups. RESULTS: We have shown that trained athletes recruit selected muscle groups to carry out a given task, which they carry out more efficiently than untrained or less experienced athletes. CONCLUSION: We have provided the basis of potential research to refine training methods, in order to develop specific muscle groups in athletes, in the hope of achieving a higher level of performance at an earlier stage in their training. We have also defined a technique that may be of clinical value in cases of muscle dysfunction.

Adult↗
PubMed2001

MRI detection of unsuspected vertebral injury in acute spinal trauma: incidence and significance.

OBJECTIVE: Multilevel spinal injury is well recognised. Previous studies reviewing the radiographs of spinal injury patients have shown an incidence of 15.2% of unsuspected spinal injury. It is recognised that magnetic resonance imaging (MRI) can identify injuries that are not demonstrated on radiographs. The objective of this study was to determine the incidence and significance of spinal injuries using MRI in comparison with radiographs. DESIGN AND PATIENTS: The radiographs and MR images of 110 acute spinal injury patients were reviewed independently of each other and the findings were then correlated to determine any unsuspected injury. RESULTS: MRI detected vertebral body bone bruises (microtrabecular bone injury) in 41.8% of spinal injury patients which were not seen on radiographs. These bone bruises were best appreciated on sagittal short tau inversion recovery MR sequences and seen at contiguous and non-contiguous levels in relation to the primary injury. CONCLUSION: This level of incidence of bone bruises has not previously been appreciated. We recommend that patients undergoing MRI for an injured segment of the spine are better assessed by MRI of the entire spine at the same time to exclude further injury.

Humans↗
PubMed2001

Nodular fasciitis: MRI appearance and literature review.

OBJECTIVE: To describe the MRI features of nodular fasciitis and to review the clinical, MRI and histologic aspects of the tumor. DESIGN AND PATIENTS: Three patients with biopsy-proven nodular fasciitis were selected for a retrospective study. A literature review was also carried out. RESULTS AND CONCLUSIONS: All the lesions appeared slightly hyperintense to skeletal muscle on T1-weighted images, and hyperintense on T2-weighted images with fat saturation [either frequency saturation or Short TI Inversion Recovery (STIR) sequences]. Two enhanced homogeneously after intravenous gadolinium, whereas the third showed heterogeneous enhancement with a nonenhancing area. Despite the difference in enhancing patterns, the histologic appearances of these lesions were similar. Our study shows that the MRI appearance of nodular fasciitis may not be related to the location of lesion. It is thought that the age of nodular fasciitis may reflect its gross morphology, and it is possible that the MRI and histologic appearances could correlate with the age of the lesion, but it would require a larger series to evaluate this concept.

Adult↗
PubMedDate not supplied

Reduction of peristaltic artifacts on magnetic resonance imaging of the abdomen: a comparative evaluation of three drugs.

BACKGROUND: Peristaltic motion is an omnipresent source of degradation in abdominal magnetic resonance (MR) imaging by blurring images and producing ghost artifacts that can mask or mimic lesions. The objective of this study was to select an effective and easy-to-administer drug to provide consistent reduction of peristaltic motion artifacts on MR images. METHODS: One hundred forty-eight adult patients with MR examinations of the abdomen were enrolled in a prospective, single-blind comparative study. Four groups were defined: (a) no-drug control group (n = 35), (b) 1 mg of intravenous (IV) glucagon (n = 19), (c) 20 mg of IV butylscopolamine (n = 28), and (d) 20 mg of oral dicyclomine (n = 66). All patients received high-density barium sulphate as a negative oral contrast medium. Quantitative image analysis was performed with operator-defined region-of-interest measurements of signal intensity. Gastrointestinal noise was measured outside the patient at the posterior part of the left hemiabdomen along the phase-encoding direction on a short inversion time inversion recovery (STIR) sequence. RESULTS: Treatment groups showed reduced gastrointestinal noise (p < 0.01). When compared with the control group, IV butylscopolamine (p < 0.05) and oral dicyclomine (p < 0.05) significantly reduced gastrointestinal noise, whereas glucagon did not. CONCLUSION: Anticholinergic drugs significantly reduced the intensity of ghost artifacts on MR imaging of the abdomen. Twenty milligrams of oral dicyclomine is an effective and safe alternative to more expensive and parenterally administered drugs such as glucagon and butylscopolamine.

Abdomen↗
PubMed2000

Cerebral dural sinus thrombosis in acute lymphoblastic leukemia with early diagnosis by fast fluid-attenuated inversion recovery (FLAIR) MR image: a case report and review of the literature.

Cerebral dural sinus thrombosis (CDST) is a very rare complication of acute lymphoblastic leukemia (ALL) in adult patients. A 23-year-old man with ALL developed dizziness, headache, diplopia, limb weakness, and a sensation of fullness in his head after his second induction chemotherapy with doxorubicin, prednisolone, and vincristine. Examinations of the peripheral blood, bone marrow, and cerebrospinal fluid showed no recurrent leukemic cells. Magnetic resonance (MR) imaging of the brain disclosed unexpected CDST at the left transverse sinus, which was seen only on the fast fluid-attenuated inversion recovery (FLAIR) sequence. His symptoms were relieved soon after treatment with heparin. MR imaging with FLAIR performed a second time 7 days later showed complete disappearance of the thrombosis. The patient was treated continuously with oral anticoagulant therapy and the symptoms did not recur. CDST can be diagnosed in its early phase by MR studies with FLAIR images. Anticoagulant therapy can be administered safely without precipitating the occurrence of infarction hemorrhage at such an early stage of CDST.

Adolescent↗
PubMed2001

Isotropic 3D fast FLAIR imaging of the brain in multiple sclerosis patients: initial experience.

The application of image registration and subtraction to detect change in multiple sclerosis (MS) disease burden on serial MR scans benefits from the use of isotropic voxels. An optimised 3D fast fluid-attenuated inversion recovery (FLAIR) sequence with 1.2- and 1.8-mm cubic voxels was compared with a 2D T2 SE sequence using standard 3-mm slices. Three-dimensional fast FLAIR and T2 SE series were obtained in 20 MS patients and 15 controls. Whole brain acquisition times for the 1.2- and 1.8-mm FLAIR were 21 and 10.5 min, respectively, for the interleaved T2 SE 16 min. Brain lesions were marked in consensus by two radiologists and the CNR was calculated in ten lesions. The mean number of lesions detected with the 1.2-mm FLAIR sequence was 115 +/- 76, compared with 85 +/- 59 for the T2 SE series ( p<0.001). The 1.8-mm FLAIR detected only 73 +/- 46 lesions. The CNR of the 1.2-mm FLAIR was significantly better than the T2 SE ( p<0.01), but not as good as the 1.8-mm FLAIR. In conclusion, isotropic 3D fast FLAIR using 1.2-mm cubic voxels is superior to the 2D T2 SE in the detection of brain lesions in MS patients. The isotropic 1.8-mm FLAIR is faster and has better contrast characteristics but lacks sensitivity.

Adult↗
PubMed2001

Craniopharyngiomas: identification of different semiological patterns with MRI.

Our objectives were to analyze different semiological patterns in craniopharyngiomas studied with CT and MR sequences. Retrospective study of 26 patients with confirmed craniopharyngiomas. All cases were examined with CT and MR imaging using a variety of pulse sequences (spin echo, inversion recovery, gradient echo in-phase and opposed-phase). The analyzed component patterns were classified as solid, calcium, proteic-like, cerebrospinal fluid (CSF)-like, hematic-like, and fatty patterns. The different patterns were related by means of contingency tables and the Fisher exact test and also to epidemiological findings and tumor size. A solid pole was detected in all patients, whereas a cystic component was present in 92.3% of the cases. Calcification was visualized in 65.3%, proteic-like in 53.8%, CSF-like in 23%, hematic-like in 19.2%, and fatty component in 15.3%. There were no statistical associations between patterns, with the exception that in no case did CSF-like and proteic-like patterns coexist ( P=0.004). Tumor size was related to components. Hematic-like (17.0+/-18.9 vs 3.9+/-2.6 mm, non-present vs present) and CSF-like (16.9+/-19.6 vs 6.5+/-4.0 mm) patterns were observed most frequently in smaller tumors, whereas larger tumors usually had proteic-like (5.9+/-5.4 vs 21.1+/-21.0 mm) and calcified (4.6+/-1.9 vs 19.1+/-19.9 mm) patterns. Computed tomography and a combination of different MR images frequently allow the detection of different semiological patterns in these tumors. Semiological patterns were correlated only to tumor size.

Adolescent↗
PubMed2002

Cerebrospinal fluid changes after intravenous injection of gadolinium chelate: assessment by FLAIR MR imaging.

Fluid-attenuated inversion recovery (FLAIR) sequence is currently used in clinical practice. Some reports emphasize the possibility that, in pathologic conditions, intravenous injection of gadolinium chelates may lead to an increased signal inside the cerebrospinal fluid (CSF). The aim of this study was to evaluate the presence of CSF signal changes in pathologic conditions causing blood-brain barrier disruption or neovascularization when imaging is performed after intravenous injection of gadolinium. We obtained FLAIR sequences after gadolinium injection from 33 patients affected by different intracranial pathologies and 10 control subjects. Patients were affected by ischemic stroke in the subacute phase, from 2 to 7 days from onset of symptoms (12 patients), meningiomas (8 patients), high-grade gliomas (5 patients), previous surgical procedures for intra-axial neoplasms (5 patients), and multiple sclerosis with active plaques (3 patients). Magnetic resonance imaging was performed in patients and controls using a 1.5-T magnet, using T2- and T1-weighted FLAIR sequences. The FLAIR sequence was acquired before and 1-3 h after injection of a standard dose of gadolinium. In those patients affected by ischemic lesions, FLAIR sequences were repeated the next days and 3-4 days later. The CSF signal was visually evaluated by two readers and scored from 0 to 3 depending by the degree of enhancement. The location of CSF signal changes (close to the lesion, hemispheric, or diffuse) was also considered. The CSF signal was markedly increased after 3 h from intravenous injection of gadolinium in all the patients with stroke, in those with previous surgery, and in those with high-grade gliomas whose neoplasm's surface was in contact with the subarachnoid spaces (SAS) or ventricles; a strong enhancement was also evident inside the necrotic component of the tumor. The CSF changes were more evident close to the pathology and/or in the hemisphere involved by the pathology. Moderate CSF enhancement was observed in the SAS close to meningiomas. No signal changes were evident in all the others. In those patients with stroke imaged in the following days, CSF signal showed to be diffuse to both hemispheres the next day and returned to normal values within 2 days. In patients affected by pathologies with blood-brain barrier breakdown or neovascularization close the SAS or the ventricles, CSF changes, related to gadolinium leakage, are likely when FLAIR sequences are acquired 2-24 h after i.v. injection of the contrast. This pattern should be known in order to differentiate it from that of subarachnoid hemorrhage.

Aged↗
PubMed2006

Imaging of inflammatory lesions at 3.0 Tesla in patients with clinically isolated syndromes suggestive of multiple sclerosis: a comparison of fluid-attenuated inversion recovery with T2 turbo spin-echo.

The aims of this study were to determine and compare the sensitivity of T2 turbo spin-echo (T2 TSE) and fluid-attenuated inversion recovery (FLAIR) sequences at 3.0 T in the detection of inflammatory lesions in patients with clinically isolated syndromes suggestive of multiple sclerosis. Forty-nine patients were examined with a 3.0 T MRI system using 5 mm axial sections of T2 TSE (2:19 min), FLAIR (4:00 min) and pre- and postcontrast T1 spin-echo sequences (3:37 min). Brain lesions were counted and categorized according to their anatomic location. Patients were classified according to Barkhof MRI criteria for FLAIR and T2 TSE sequences. The FLAIR sequence detected more lesions in every anatomic region except for the infratentorial region. The higher sensitivity was significant for the total number of lesions (p<0.01), the juxtacortical (p<0.01), and the periventricular (p=0.01) region. A 9% increase of infratentorial lesions using the T2 TSE sequence was not significant. The higher sensitivity using the FLAIR sequence resulted in one additional MRI criterion in nine patients, whereas the better detection of infratentorial lesions using the T2 TSE sequence resulted in additional MRI criteria in three patients. In conclusion, FLAIR provides the highest sensitivity when compared with the T2 TSE, although T2 TSE still has a diagnostic relevance in terms of MRI criteria classification.

Adolescent↗
PubMed2006

Screening for bone metastases: whole-body MRI using a 32-channel system versus dual-modality PET-CT.

The diagnostic accuracy of screening for bone metastases was evaluated using whole-body magnetic resonance imaging (WB-MRI) compared with combined fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) (FDG-PET-CT). In a prospective, blinded study, 30 consecutive patients (18 female, 12 male; 24-76 years) with different oncological diseases and suspected skeletal metastases underwent FDG-PET-CT as well as WB-MRI with the use of parallel imaging (PAT). With a 32-channel scanner, coronal imaging of the entire body and sagittal imaging of the complete spine was performed using T1-weighted and short tau inversion recovery (STIR) sequences in combination. PET-CT was conducted using a low-dose CT for attenuation correction, a PET-emission scan and diagnostic contrast-enhanced CT scan covering the thorax, abdomen and pelvis. Two radiologists read the MRI scans, another radiologist in combination with a nuclear medicine physician read the PET-CT scans, each in consensus. The standard of reference was constituted by radiological follow-up within at least 6 months. In 28 patients, 102 malignant and 25 benign bone lesions were detected and confirmed. WB-MRI showed a sensitivity of 94% (96/102), PET-CT exams achieved 78% (79/102; P<0.001). Specificities were 76% (19/25) for WB-MRI and 80% (20/25) for PET-CT (P>0.05). Diagnostic accuracy was 91% (115/127) and 78% (99/127; P<0.001), respectively. Cut-off size for the detection of malignant bone lesions was 2 mm for WB-MRI and 5 mm for PET-CT. WB-MRI revealed ten additional bone metastases due to the larger field of view. In conclusion, WB-MRI and FDG-PET-CT are robust imaging modalities for a systemic screening for metastatic bone disease. PAT allows WB-MRI bone marrow screening at high spatial resolution and with a diagnostic accuracy superior to PET-CT.

Adult↗
PubMed1997

1H T1 and T2 measurements of the MR imaging contrast agents Gd-DTPA and Gd-DTPA BMA at 1.5T.

We report in vitro T1 and T2 relaxation studies for the open-chain complexes Gd-DTPA and Gd-DTPA BMA. Measurements were performed on phantoms containing aqueous and plasma solutions of different concentrations by MR imaging in a 1.5T superconducting whole-body scanner. Longitudinal relaxation times T1 were evaluated from serial turbo-FLASH experiments for concentrations less than 1 mM, whereas for larger concentrations the values were obtained from a standard inversion recovery (IR) sequence. Transverse relaxation times T2 were determined using multi-echo spin-echo MRI protocols. The T1 and T2 relaxivities of the nonionic Gd-DTPA BMA are similar to those of the Gd-DTPA. The temperature dependencies of the relaxivities were determined over a temperature interval ranging from 21 to 50 degrees C and were found to be slightly different for the two contrast agents. In the case of Gd-DTPA BMA a larger deviation of the expected temperature behavior of the relaxivities was observed as compared with Gd-DTPA. Deviations from a strictly linear dependence of relaxation times on temperature were found at lower concentrations in aqueous solutions. In plasma solutions a high T1/T2 ratio was observed for low concentrations, which decreased monotonically with increasing concentrations.

Contrast Media↗
PubMed2000

Magnetic resonance imaging with rectal Gd-DTPA: new tool for the diagnosis of perianal fistula.

This study investigated the effectiveness of magnetic resonance imaging (MRI) with rectal administration of the enteral contrast agent gadolinium diethylene triamine pentaacetic acid (Gd-DTPA) in the diagnosis of recurrent perianal fistulae, assessing the number, anatomical extent, location, and signal intensities of various lesions. Fistulas were examined by MRI before and after rectal administration of Gd-DTPA in 50 patients (excluding fistulas due to inflammatory bowel disease). Surgical findings were compared with both pre- and postcontrast T1-weighted, T2-weighted, and short T1 inversion recovery (STIR) sequences. Of the 68 fistulous tracts detected surgically, precontrast imaging identified 16 by T1-weighted images (hypointense), 27 by T2-weighted images (hyperintense or iso- to weakly hyperintense), and 54 by STIR. Postcontrast imaging identified 29 by T1-weighted images, 58 by T2-weighted, and 54 by STIR. MRI with rectal administration of Gd-DTPA thus facilitates determination of fistula tracts, which are better resolved by precontrast STIR than by either precontrast T1- or T2-weighted images. Postcontrast T2-weighted images were substantially superior to T1-weighted. Both noncontrast STIR and postcontrast T2-weighted sequences were adequate for classifying fistulas in ano, but in complex recurrent anal fistula postcontrast T2-weighted images were more helpful.

Adult↗
PubMed2006

Promoter activity of a putative pollen monosaccharide transporter in Petunia hybrida and characterisation of a transposon insertion mutant.

For the growth of the male reproductive cells of plants, the pollen, the presence of sufficient sucrose or monosaccharides is of vital importance. From Petunia hybrida a pollen-specific putative monosaccharide transporter designated PMT1 (for petunia monosaccharide transporter) has been identified previously. The present work provides an in-depth analysis and characterisation of PMT1 in the context of pollen development with the GUS reporter gene and an insertion mutant. The promoter of the pollen-specific putative PMT1 gene has been isolated by inverse PCR and sequenced. Analysis of plants transformed with the promoter-GUS fusion confirmed the specificity of this gene, belonging to the late pollen-specific expressed genes. GUS activity was detected even after 24 h of in vitro pollen germination, at the pollen tube tip. To elucidate the importance of PMT1 for gametophyte development and fertilisation, we isolated a mutant plant containing a transposon insertion in the PMT1 gene by the dTph1 transposon-tagging PCR-based assay. The PMT1 mutant contained a dTph1 insertion in position 1474 bp of the transcribing part of the gene, before the last two transmembrane-spanning domains. Analysis of the progeny of the heterozygous mutant after selfing revealed no alterations in pollen viability and fertility. Mature pollen grains of a plant homozygous for the transposon insertion were able to germinate in vitro in a medium containing sucrose, glucose, or fructose, which indicates that PMT1 is not essential for pollen survival. Several explanations for these results are discussed in the present work.

Amino Acid Sequence↗