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PubMed1999

[MRI of plantar fasciitis].

PURPOSE: The purpose of this study was to determine the type and frequency of characteristic bone and soft tissue changes on MRI of patients with a clinical diagnosis of plantar fasciitis. MATERIALS AND METHODS: 28 patients with a clinical diagnosis of plantar fasciitis underwent MR imaging. Besides T1- and T2-weighted sequences, short-tau-inversion-recovery sequences were used routinely. In 27 patients T1-weighted images after intravenous contrast injection were acquired additionally. As a control group the images of 15 patients without clinical signs for plantar fasciitis were evaluated. RESULTS: In 25 of 28 cases (89%) the clinical diagnosis of plantar fasciitis was established by MR imaging. The most common finding was a peritendinous edema at the calcaneal insertion site which was found in all 25 patients. In 19 of 25 cases (76%) a bone marrow edema of the calcaneus was present. In 14 of 25 cases (56%) an intratendinous signal intensity increase of the plantar fascia could be observed which showed contrast enhancement in 12 cases. Compared to the control group (mean thickness 3.3 mm) the plantar fascia showed significant thickening in the 25 MR positive patients (mean thickness 6.72 mm). DISCUSSION: Besides thickening of the plantar fascia and intratendinous signal intensity increase with contrast enhancement to some extent, bone marrow edema of the calcaneus and peritendinous edema close to the plantar fascia are characteristic signs of plantar fasciitis on MRI. Both signs can reliably be seen on STIR sequences only.

Adult↗
PubMed2003

[Diffusion-weighted imaging of acute vertebral compression: Differential diagnosis of benign versus malignant pathologic fractures].

PURPOSE: Our purpose was to assess the value of diffusion-weighted steady-state free precession (SSFP) sequence for differentiating between benign and pathologic compression fractures. MATERIALS AND METHODS: Forty-nine patients with 63 acute vertebral compression fractures caused by osteoporosis (n = 23), trauma (n = 7), malignancy (n = 30), infection (n = 3) were examined with a diffusion-weighted SSFP sequence (diffusion gradient strength; 23 mT/m, diffusion pulse length 5 ms), T1-weighted turbo spin-echo sequence, and short-inversion-time (TI 150 ms) T2-weighted turbo inversion recovery sequence. The signal intensity characteristics were analyzed qualitatively and quantitatively for all sequences. Statistical analysis was performed with the Student's t test. RESULTS: In diffusion-weighted MR imaging, benign osteoporotic and traumatic fractures were hypo- to isointense to adjacent normal vertebral bodies. Pathologic and infectious compression fractures were hyperintense to normal vertebral bodies. Pathologic vertebral fractures had positive bone marrow contrast ratios at diffusion-weighted imaging, whereas non infectious benign vertebral fractures had negative values (p < 0.001). The difference in bone marrow contrast ratios for benign and pathologic compression fractures at T1-weighted TSE and T2-weighted turbo IR was not significant (p > 0.01). CONCLUSION: Diffusion-weighted SSFP sequence provides unique information that significantly impacts the accuracy of radiologic diagnosis. Diffusion-weighted SSFP sequence may allow the differentiation of acute benign osteoporotic fractures from malignant compression fractures. Acute benign osteoporotic or traumatic fractures show hypointense or isointense signal on diffusion-weighted sequences that reflects persistent free water proton mobility. Malignant compression fractures show hyperintensity compared with normal surrounding bone marrow probably due to altered water proton mobility within the neoplasm.

Adult↗
PubMed1993

Inversion of a chicken ets-1 proto-oncogene segment in avian leukemia virus E26.

The segment of the avian leukemia virus E26 genome near the termination of the p135gag-myb-ets open reading frame contains an inversion of the chicken ets-1 sequence. The inversion contains at least 41 bp and may be as large as 46 bp. This results in the replacement of 13 amino acids of chicken ets-1, with 16 amino acids derived from reverse complement of the normal ets-1 coding strand or read-through into E26 env sequences. At least 13 of these codons are specified by the inverted ets sequences. This represents the first reported occurrence of inverted oncogene sequences in a natural retrovirus. The inverted ets sequences are immediately followed by sequences homologous to the Rous sarcoma virus Prague B env gene. Since the E26 env sequence is more closely related to subgroup B avian retroviruses than to avian retroviruses from subgroups A, C, D, or E, the progenitor of E26 was a virus belonging to avian retrovirus subgroup B.

Avian Leukosis Virus↗
PubMed1997

DNA replication promotes high-frequency homologous recombination during Autographa californica multiple nuclear polyhedrosis virus infection.

The relative ease with which foreign genes can be incorporated into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) indicates that a highly efficient recombinational process exists within infected cells. However, it is unclear whether this is due to marker transfer mediated by host cell enzymes or recombination events promoted by AcMNPV itself. To address the latter possibility, a pair of inverted repeat IS50 elements derived from the bacterial transposon Tn5 was inserted into the polyhedrin gene locus of the AcMNPV genome. Inversion of Tn5 sequences arising from recombination between its IS50 repeats could be readily detected in this virus, indicating that AcMNPV DNA undergoes high-frequency recombination during infection. To further characterize this process, a transient recombination assay was developed and used to identify the cis- and trans-acting requirements for Tn5 inversion in AcMNPV. A transfected Tn5-containing plasmid was found to undergo the same sequence inversion events seen in the viral genome, but only if it also contained a putative AcMNPV origin of replication (homologous region 2) in cis and was replicated by AcMNPV gene products supplied in trans. Taken together, these results indicated that recombination events which occur in infected cells were strictly dependent upon AcMNPV-mediated DNA replication. Direct support for this hypothesis was provided by the observation that the minimal set of AcMNPV genes that was essential for plasmid DNA replication also promoted recombination events leading to Tn5 inversion in the absence of any other viral function. Finally, using a panel of deletion mutants of the IS50 elements in Tn5, sequence inversion was shown to be the result of homologous rather than site-specific recombination, since it occurred independently of a discrete sequence within the transposon. These results demonstrate that the AcMNPV DNA replication machinery exhibits a strong propensity to promote homologous recombination events during infection and is likely to play a role in the high frequency of marker transfer observed in this virus.

Animals↗
PubMed1997

Use of fluid-attenuated inversion recovery (FLAIR) pulse sequences for differential diagnosis of hepatic hemangiomas and hepatic cysts.

Fluid-attenuated inversion recovery (FLAIR) imaging of hepatic hemangiomas (10 patients, 16 lesions) and hepatic cysts (8 patients, 10 lesions) was performed. All hemangiomas were hypointense on T1-weighted images and hyperintense on T2-weighted images. With Gd-DTPA (0.1 mmol/kg), all hemangiomas were enhanced but not all cysts. It was necessary to perform contrast enhanced imaging to differentiate hepatic hemangiomas from hepatic cysts. However, on FLAIR imaging, hepatic hemangiomas were strongly hyperintense and 9 of the 10 hepatic cysts were isointense. One of the hepatic cysts was slightly hyperintense. FLAIR images were useful in differential diagnosis of hepatic hemangiomas and hepatic cysts without using Gd-DTPA.

Cysts↗
PubMed1992

Monomers and dimers of the RepA protein in plasmid pSC101 replication: domains in RepA.

The replication of plasmid pSC101 requires the plasmid-encoded protein RepA. This protein has a double role: it binds to three directly repeated sequences in the pSC101 origin and promotes replication of the plasmid; it binds to two inversely repeated sequences in its promoter region and regulates its own transcription. A series of RepA protein derivatives carrying deletions of the C-terminal region were assayed for specific binding. We found that the last third of the protein is not needed for binding to the various specific sites. Truncated proteins that still bind can also form heterodimers with a wild-type protein. Analysis of band retardation assays conducted with wild-type and truncated proteins indicates that RepA binds to directly repeated sequences as a monomer and to inversely repeated sequences as a dimer.

Bacterial Proteins↗
PubMed1987

STIR sequences in NMR imaging of the optic nerve.

Orbital fat surrounding the optic nerve causes considerable difficulties in NMR imaging due to its high image intensity and the chemical shift artefact. We have investigated the ability of inversion recovery sequences with short inversion times (STIR sequences) to suppress fat signals in imaging the optic nerve. We have also compared the contrast attainable with STIR sequences with that obtainable from other sequences. Measurements were made on 4 normal controls and 5 patients with multiple sclerosis (MS) to obtain typical values of relaxation times and proton densities for orbital fat, cerebral white matter and MS lesions. The fat T1 measurements were used to predict an appropriate inversion time for the STIR sequence and estimate how much residual fat signal might be expected as a result of natural variations in fat T1. STIR sequences can be used to suppress the signal from orbital fat with little residual signal. Measurements from white matter and MS lesions were used to predict the contrast between normal and pathological tissues that is attainable with STIR sequences. STIR contrast compares favourably with that obtainable from other sequences.

Humans↗
PubMed2000

Optimization and evaluation of the signal intensity change in multisection oxygen-enhanced MR lung imaging.

The behavior of the signal intensity in MRI of human lungs was investigated during inhalation of pure oxygen. Nine volunteers were examined, five using a breath-hold and four using a non-breath-hold technique. Four coronal slices were acquired in each volunteer using an inversion recovery turbo spin-echo sequence. The inversion time of the sequence was optimized for maximum contrast. Breathing of pure oxygen and room air was alternated in the volunteers. Breath-hold and non-breath-hold cases were compared. Breathing pure oxygen lead to a statistically significant signal intensity increase (up to 18%) compared to breathing room air. In addition, T(1) maps were acquired during breathing 100% oxygen and room air. Inhalation of pure oxygen reduced the mean T(1) time of the lungs from 1280 (+/-85) msec to 1224 (+/-139) msec without breath-hold and from 1219 (+/-176) to 1074 (+/-92) msec with breath-hold. Therefore, an optimized sequence and measurement protocol provided significant signal intensity changes utilizing 100% oxygen. Magn Reson Med 43:860-866, 2000.

Adult↗
PubMedDate not supplied

MR imaging of neuronal migrational disorders.

Neuronal migrational disorders of the brain represent abnormalities in the formation of the neocortex caused by faulty migration of the subependymal neuroblasts. These migrational anomalies include lissencephaly (agyria/pachygyria), pachygyria, schizencephaly, heterotopias, hemimegalencephaly, and polymicrogyria. We used MR imaging (performed on a 0.5-T or 1.5-T scanner) to evaluate 21 patients who had neuronal migratory anomalies. Four patients had lissencephaly, seven had pachygyria, including one patient with hemimegalencephaly, seven had schizencephaly, and three had heterotopias. All MR scans included T1-weighted spin-echo sequences, and seven also had inversion-recovery sequences. The cortical surface, cortex, and gray-white matter interface were well evaluated with both sequences; however, the inversion-recovery images were superior. All but two patients were imaged in both the axial and coronal planes: both projections demonstrated well the migrational abnormalities. MR is an excellent method for diagnosing the migrational anomalies of lissencephaly, pachygyria, schizencephaly, heterotopias, and hemimegalencephaly; it appears to be the imaging method of choice for evaluating these disorders.

Adolescent↗
PubMed1997

Significance of short tau inversion recovery magnetic resonance sequence in the management of skeletal injuries.

The conventional radiographs and urgent short tau inversion recovery (STIR) magnetic resonance image (MRI) examinations of 27 consecutive patients with occult bony injuries were prospectively analysed over a 12 month period. A STIR MRI study was undertaken where the plain films were normal (n = 15) or inconclusive (n = 12) and where the patients' clinical setting was highly suggestive of an underlying bony injury. In six patients, MRI only revealed soft-tissue injuries or joint effusions and did not demonstrate any bony injury but in the remainder fractures or bone contusions were shown to be present. The MRI studies were performed on a 0.2 Tesla lower field strength unit and the examinations were expeditiously performed, inexpensive, and done on a priority basis between electively booked patients. Radio-isotope studies were not available and hence were not included in the study protocol. Apart from demonstrating the value of STIR MRI (without additional T1-weighted sequences in most patients), the purpose of this study was to highlight the alteration in management in 18/27 patients (66%) and the significant alteration in management in six of these patients.

Adult↗
PubMed2004

[Report on the investigation of lower extremity osteonecrosis with magnetic resonance imaging in recovered severe acute respiratory syndrome in Guangzhou].

OBJECTIVE: To report the occurrence of lower extremity avascular abnormalities in 124 cases of recovered severe acute respiratory syndrome (SARS) health care workers of four hospitals in Guangzhou and preliminary investigate the correlation with the treatment of steroid. METHODS: 124 health care workers with recovered SARS from four hospitals in Guangzhou were examined with MR imaging of the lower extremity including bilateral hips and knees. In 124 health care workers, 38 cases have not treated with steroid, while 86 cases have treated with varied dosage. The imaging protocol was consisted of screening and full examination. Coronal T1-weighted imaging and short tau inversion recovery sequence were defined as the screening examination. The full examination was defined as images from the screening examination plus three additional imaging sequences: transverse and coronal T2-weighted imaging and short tau inversion recovery sequence. RESULTS: In 86 health care workers, 5 cases were found positive in the lower extremity. Osteonecrosis was found in 3 cases. One was involved in bilateral femoral head, and another was unilateral femoral head, and the remaining one was bilateral femoral heads and unilateral femoral condyle and tibial condyle. Bilateral femoral and tibial marrow edema were found in one case. Femoral infarction with significant calcification occurred in one health care worker. Logistic regression analysis indicated that the presence of avascular abnormalities was related with maximum daily dosage. CONCLUSION: Osteonecrosis definitely exists in the minority of health care workers with recovered SARS in Guangzhou, who had treated with steroid. The maximum daily dosage of steroid may significantly influence on the occurrence of avascular abnormalities.

Adolescent↗
PubMed1997

[Comparison of magnetic resonance Spin-echo sequences and fat-suppressed sequences in bone diseases].

Thirty-two patients affected with skeletal conditions were examined with MRI using Short TI Inversion Recovery sequence and Spectral Presaturation with Inversion Recovery (SPIR) sequence as well as Spin-Echo (SE) T1-weighted sequence and Fast Spin-Echo (FSE) T2-weighted sequence to compare their value in the assessment of skeletal lesions. SPIR sequence was performed after intravenous injection of Gd-DTPA. The lesions included primary bone tumors (10 cases: 1 osteosarcoma, 1 periosteal sarcoma, 1 Ewing's sarcoma, 1 chondrosarcoma, 2 non-ossifying fibromas, 1 chondroma, 1 chondromyxoid fibroma, 1 desmoplastic fibroma and 1 bone cyst), metastases (7 cases: 3 prostate, 3 breast, 1 lung-squamous cell carcinoma), infections (12 cases: 9 osteomyelitis, 3 spondylodiscitis), sacroiliitis (1 case) and posttraumatic bone bruise (2 cases of bone marrow edema). The four sequences were compared by using both qualitative and quantitative evaluation. Qualitative evaluation showed that STIR sequence was better than SPIR sequence (performed with Gd-DTPA) for lesion conspicuity (p < .016) and for signal intensity uniformity (p < .03). Compared with SE T1 and FSE T2 sequences, fat-suppressed sequences were superior for conspicuity, margins, and extension of the lesions (range of p < .001-.017). Only SPIR with Gd-DTPA sequence, compared with SE T1 sequence for lesion conspicuity was not statistically significantly different. Quantitative evaluation showed statistically significant higher values of percent contrast (%C) and contrast-to-noise ratio (C/N) for STIR sequence compared with SPIR sequence (%C p < .004; C/N p < .040). This study suggests that STIR sequence and SE T1-weighted sequence provide high sensitivity in lesion detection and good anatomical definition. The use of a fat-suppressed sequence with Gd-DTPA can be useful for lesion characterization.

Adolescent↗
PubMed1996

[FLAIR images of patients with head injuries].

FLAIR (fluid-attenuated inversion recovery) images are MR images obtained with an inversion recovery sequence, which has a long inversion time (TI) and a long echo time (TE). We examined 29 cases (49 graphics) of cerebral contusion, 11 cases (22 graphics) of diffuse axonal injury (DAI) and 11 cases (11 graphics) of traumatic subarachnoid hemorrhage (t-SAH) with FLAIR sequence consisting of a repetitive time (TR) of 6500 msec, TI of 1700 msec and TE of 110 msec, and these graphics were compared with T2-weighted images by spin-echo sequence (TR 2500 msec, TE 90 msec) and computed tomographic (CT) scans. Some lesions of DAI were demonstrated more clearly with FLAIR images than with conventional T2-weighted images. Although contusion could be detected with FLAIR images as well as with conventional T2-weighted images, lesions adjacent to cerebral sulci were better delineated with FLAIR images. Because the cerebrospinal fluid signals in cerebral sulci were low-intensity, FLAIR images were useful in detecting lesions of the cerebral cortex adjacent to cerebral sulci. Although it has been reported that detection of SAH is difficult with standard T1- and T2-weighted images, the presence of t-SAH could be confirmed with FLAIR images as seen in CT scans.

Adult↗
PubMed1993

Homologous recombination among three intragene Alu sequences causes an inversion-deletion resulting in the hereditary bleeding disorder Glanzmann thrombasthenia.

The crucial role of the human platelet fibrinogen receptor in maintaining normal hemostasis is best exemplified by the autosomal recessive bleeding disorder Glanzmann thrombasthenia (GT). The platelet fibrinogen receptor is a heterodimer composed of glycoproteins IIb (GPIIb) and IIIa (GPIIIa). Platelets from patients with GT have a quantitative or qualitative abnormality in GPIIb and GPIIIa and can neither bind fibrinogen nor aggregate. Very few genetic defects have been identified that cause this disorder. We describe a kindred with GT in which the affected individuals have a unique inversion-deletion mutation in the gene for GPIIIa. Patient platelets lacked both GPIIIa protein and mRNA. Southern blots of patient genomic DNA probed with an internal 1.0-kb GPIIIa cDNA suggested a large rearrangement of this gene but were normal when probed with small GPIIIa cDNA fragments that were outside the mutation. Cytogenetics and pulsed-field gel analysis of the GPIIIa gene were normal, making a translocation or a very large rearrangement unlikely. Additional Southern analyses suggested that the abnormality was not a small insertion. We constructed a patient genomic DNA library and isolated fragments containing the 5' and 3' breakpoints of the mutation. The nucleotide sequence from these genomic clones was determined and revealed that, relative to the normal gene, the mutant allele contained a 1-kb deletion immediately preceding a 15-kb inversion. The DNA breaks occurred in two inverted and one forward Alu sequence within the gene for GPIIIa and in the left, right, and left arms, respectively, of these sequences. There was a 5-bp repeat at the 3' terminus of the inversion.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1996

The MR appearance of vaginal fistulas.

OBJECTIVE: The aim of this study was to determine the accuracy of MR imaging in revealing complex vaginal fistulas. SUBJECTS AND METHODS: Fifteen patients with clinical symptoms of vaginal fistulas were examined with MR imaging, using a combination of T1-weighted, T2-weighted, and fast multiplanar inversion recovery sequences in the axial plane, along with T2-weighted and fast multiplanar inversion recovery sequences in the sagittal plane. Observers examined the scans for a fistula and any associated masses or collections. The MR findings were recorded with the observers unaware of the results of cystoscopy and sigmoidoscopy under anesthesia. The MR findings were correlated with examination under anesthesia. RESULTS: Vaginal fistulas were seen in ten patients. All fistulas were confirmed surgically. Of the five patients with no fistulas revealed on MR imaging, examination under anesthesia also revealed no fistulas in four. However, in the fifth patient, examination under anesthesia revealed an epithelialized track, which was not seen on MR imaging. CONCLUSION: MR imaging was accurate in revealing and delineating the extent of vaginal fistulas in patients with clinical symptoms of such fistulas.

Adult↗
PubMedDate not supplied

[Intravenous administration of gadolinium DPTA in proton spin tomography of the knee joint].

UNLABELLED: In a prospective study we evaluated the benefits of iv-application of gadolinium-DPTA examining 25 patients with degenerative disease of the knee joint by MRI (1.0 Tesla). All patients were scanned with standard spin echo sequences (SE 500/20), short time inversion recovery sequences (STIR 1600/100), and FEDIF sequences (FEDIF 500/10). After gadolinium-DPTA application (0.1-0.35 mmol/kg BW) the patients were scanned with spin echo sequences (SE SE 500/20), and FEDIF sequences (FEDIF 500/10). After iv-Gadolinium the synovial membrane of joints with inflammation show significant increase of the signal. Due to this effect a differentiation between joint effusion and hypertrophic synovia is possible. Small areas of local synovitis not visible before the use of gadolinium can be documented. A differentiation between degenerative subchondral cysts and cysts due to an inflammatory process is possible. CLINICAL RELEVANCE: The use of iv-application of gadolinium-DPTA in patients with degenerative joint disease seems to offer additional information. With iv-application all shortcomings of intraarticular use can be avoided. The differentiation between degenerative and inflammatory processes is possible.

Contrast Media↗
PubMed2001

Diagnostic value of increased diffusion weighting of a steady-state free precession sequence for differentiating acute benign osteoporotic fractures from pathologic vertebral compression fractures.

BACKGROUND AND PURPOSE: Differentiating acute benign from neoplastic vertebral compression fractures can pose a problem in differential diagnosis on routine MR sequences, as signal changes can be quite similar. Our purpose was to assess the value of increasing the diffusion weighting of a diffusion-weighted steady-state free precession (SSFP) sequence for differentiating these two types of vertebral compression fractures. METHODS: Twenty-nine patients with 32 acute vertebral compression fractures caused by osteoporosis (n = 15) or malignancy (n = 17) were examined with a diffusion-weighted SSFP sequence, a T1-weighted spin-echo sequence, and a short-inversion-time inversion recovery sequence. The SSFP sequence was performed with increased diffusion weighting (delta = 0.6, 3.0, 6.0, and 9.0 ms). The signal intensities of the fractured vertebral bodies were rated on a five-point scale from markedly hypointense to markedly hyperintense relative to normal adjacent vertebral bodies. Quantitative analysis was performed by region-of-interest measurements and by calculating the bone marrow contrast ratio. Statistical analysis was performed with the Mann Whitney U test and Student's t test. RESULTS: At delta = 3 ms, the osteoporotic fractures yielded hypointense signal in seven cases, isointense signal in six, and hyperintense signal in two. The fractures showed a progressive signal loss with increased diffusion weighting, so that hypointensity was reached in all but one case. All metastatic fractures had hyperintense signal with delta = 3 and 6.0 ms. With delta = 9.0 ms, four fractures became isointense. CONCLUSION: Increasing diffusion weighting can reduce false-positive hyperintense osteoporotic fractures or make hypointensity more obvious in cases of osteoporotic fractures.

Acute Disease↗
PubMed1976

Sequence arrangement in herpes simplex virus type 1 DNA: identification of terminal fragments in restriction endonuclease digests and evidence for inversions in redundant and unique sequences.

It has been proposed by Sheldrick and Berthelot (1974) that the terminal sequences of herpes simplex virus type 1 (HSV-1) DNA are repeated in an internal inverted form and that the inverted redundant sequences delimit and separate two unique sequences, S and L. In this study the sequence arrangement in HSV-1 DNA has been investigated with restriction endonuclease cleavage, end-labeling studies, and molecular hybridization experiments. The terminal fragments in digests with restriction endonucleases Hind III, Hpa-1, EcoRI and Bum were identified and shown to be consistent with the Sheldrick and Berthelot model. Inverted fragments which contain unique sequences as well as redundant sequences, and which the model predicts, were identified by DNA-DNA hybridization studies. Further cleavage of Bum fragments with Hpa-1 also revealed inversions of the terminal sequences that contained unique sequences. The results obtained showed that the unique sequences S and L are relatively inverted in different DNA molecules in the population, resulting in the presence of four related genomes with rearranged sequences in apparently equal amounts. The redundant sequences bounding S do not share complete sequence homology with those bounding L, but hybridization studies are presented which show that the terminal 0.3% of the genome is repeated in every redundant sequence.

Base Sequence↗