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Dive into the research topics where Anders F. Christensen is active.

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Featured researches published by Anders F. Christensen.


Regional Anesthesia and Pain Medicine | 2012

Distribution Patterns, Dermatomal Anesthesia, and Ropivacaine Serum Concentrations After Bilateral Dual Transversus Abdominis Plane Block

Jens Børglum; Kenneth Jensen; Anders F. Christensen; Lotte C. G. Hoegberg; Sys Stybe Johansen; P.-A. Lønnqvist; Tejs Jansen

Background and Objectives The ability of transversus abdominis plane (TAP) blocks to anesthetize the upper abdomen remains debatable. We aimed to describe the local anesthetic distribution following ultrasound-guided TAP blocks with repeated magnetic resonance imaging investigations and to relate this to the resulting dermatomal anesthesia. Methods Eight volunteers were included in a randomized, observer-blinded study. Sixty milliliters of ropivacaine 0.375% was administered: 1 injection of 30 mL as a lateral classic TAP block, followed by a sham upper intercostal TAP block, and on the contralateral side, 2 separate 15-mL injections at the upper intercostal and lateral classic TAP plexuses, respectively. The primary outcome measure was magnetic resonance imaging–assessed area expansion of all injectates over a 6-hr period. Dermatomal anesthesia and sequential serum ropivacaine levels were recorded at the same time intervals. Results All injectate areas expanded in a statistically significant manner in the anterior abdominal wall. Lateral classic TAP blocks with 30-mL injectates did not extend into the upper intercostal TAP plexus. The dual 15-mL injectates on the other hemiabdomen remained within the upper intercostal and lateral classic TAP compartments and resulted in significantly (P < 0.018) more widespread dermatomal anesthesia. Measured serum ropivacaine concentrations were below the potential level of toxicity. Conclusions Magnetic resonance imaging analysis revealed a significant time-dependent expansion of injectates. Magnetic resonance imaging and the degree of dermatomal anesthesia confirmed that the upper and lateral TAP compartments do not appear to communicate. Separate injections at the upper intercostal and lateral classic TAP plexuses are necessary to block the entire abdominal wall.


Diseases of The Colon & Rectum | 2004

Three-dimensional anal endosonography may improve staging of anal cancer compared with two-dimensional endosonography.

Anders F. Christensen; Michael B. Nielsen; Svend Aage Engelholm; Henrik Roed; Lars Bo Svendsen; Hanne Christensen

PURPOSEThree-dimensional (3-D) endosonography is a new method of staging anal carcinoma that has not yet been validated in comparison with two-dimensional (2-D) endosonography, the latter using only a single scan plane. The aim of this study was to investigate the differences between the two endosonographic techniques.METHODSThirty patients with an endosonographically detectable anal tumor were examined with a 10 MHz rotating endoprobe. Cross-sectional images of the anal sphincters were stored on a 3-D system during retraction of the endoprobe through the anal canal. Afterwards, any projection could be reconstructed. Cross-sectional images (2-D) were compared with reconstructed projections (3-D) according to five parameters concerning tumor spread and presence of regional lymph nodes. In this study, a scale of 0 to 5 points on critical issues was used; ideally, the results should be identical in 2-D and 3-D endosonography.RESULTSThe 3-D method detected a median of 5 diagnostic findings, compared with a median of 4 findings with the 2-D method (P = 0.001). In eight patients the lateral tumor margin was visualized only by 3-D endosonography. The median number of lymph nodes visualized in 3-D was 1 (range, 0-13), in 2-D the median number was 0 (range, 0-6), P = 0.002.CONCLUSIONSUse of 3-D endosonography in patients with anal carcinoma improves detection of perirectal lymph nodes and may improve that of tumor invasion, compared with 2-D endosonography. This may affect local tumor staging and thus planning of treatment. A study with histopathologic correlation is needed to verify this endosonographic study.


Diseases of The Colon & Rectum | 2006

Three-Dimensional Anal Endosonography May Improve Detection of Recurrent Anal Cancer

Anders F. Christensen; Michael B. Nielsen; Lars Bo Svendsen; Svend Aage Engelholm

PurposeIn our center since 2001, follow-up examination has included three-dimensional endosonography in all patients with suspicion of local recurrence of anal cancer. This study was designed to investigate whether three-dimensional endosonography surpassed two-dimensional endosonography as a diagnostic tool for patients with suspected local recurrence.MethodsThis prospective study included 38 consecutive patients who have had anal carcinoma and were investigated using three-dimensional endosonography in combination with anoscopy and digital rectal examination at Rigshospitalet from July 2001 to January 2005 under suspicion of local recurrence. All endosonographic examinations—two-dimensional, three-dimensional, and three-dimensional in combination with anoscopy and digital rectal examination—were evaluated by blinded observers. The observers scored each examination according to a five-point scale in which a score from 1 to 3 was regarded as benign endosonographic findings and a score from 4 to 5 was regarded as malignant endosonographic findings. The endosonographic diagnosis for each examination was compared with histologic evaluation or when no biopsy had been taken with a follow-up period of at least six months. If a patient showed no signs of local recurrence in the follow-up period, no local recurrence was considered to be present at the time of the investigation.ResultsThe sensitivity was 1.0 for three-dimensional endosonography in combination with palpation, 0.86 for three-dimensional endosonography alone, and 0.57 for two-dimensional endosonography. The differences between two-dimensional endosonography and three-dimensional endosonography alone as well as two-dimensional endosonography and three-dimensional endosonography + anoscopy and digital rectal examination both reached significance with P values <0.05.ConclusionsThis study indicates that three-dimensional endosonography surpasses two-dimensional endosonography in the evaluation of patients with suspicion of local recurrence of anal cancer especially in combination with anoscopy and digital rectal examination.


BMJ Open | 2013

Prevalence and long-term clinical significance of intracranial atherosclerosis after ischaemic stroke or transient ischaemic attack: a cohort study

Christian Ovesen; Annemette Abild; Anders F. Christensen; Sverre Rosenbaum; Christine Krarup Hansen; Inger Havsteen; Jens Kellberg Nielsen; Hanne Christensen

Objectives We investigated the prevalence and long-term risk associated with intracranial atherosclerosis identified during routine evaluation. Design This study presents data from a prospective cohort of patients admitted to our stroke unit for thrombolysis evaluation. Setting and participants We included 652 with a final diagnosis of ischaemic stroke or transient ischaemic attack (TIA) from April 2009 to December 2011. All patients were acutely evaluated with cerebral CT and CT angiography (CTA). Acute radiological examinations were screened for intracranial arterial stenosis (IAS) or intracranial arterial calcifications (IAC). Intracranial stenosis was grouped into 30–50%, 50–70% and >70% lumen reduction. The extent of IAC was graded as number of vessels affected. Primary and secondary outcome measure Patients were followed until July 2013. Recurrence of an ischaemic event (stroke, ischaemic heart disease (IHD) and TIA) was documented through the national chart system. Poor outcome was defined as death or recurrence of ischaemic event. Results 101 (15.5%) patients showed IAS (70: 30–50%, 29: 50–70% and 16: >70%). Two-hundred and fifteen (33%) patients had no IAC, 339 (52%) in 1–2 vessels and 102 (16%) in >2 vessels. During follow-up, 53 strokes, 20 TIA and 14 IHD occurred, and 95 patients died. The risk of poor outcome was significantly different among different extents of IAS as well as IAC (log-rank test p<0.01 for both). In unadjusted analysis IAS and IAC predicted poor outcome and recurrent ischaemic event. When adjusted, IAS and IAC independently increased the risk of a recurrent ischaemic event (IAS: HR 1.67; CI 1.04 to 2.64 and IAC: HR 1.22; CI 1.02 to 1.47). Conclusions Intracranial atherosclerosis detected during acute evaluation predicts an increased risk of recurrent stroke.


Stroke | 2014

Time Course of Early Postadmission Hematoma Expansion in Spontaneous Intracerebral Hemorrhage

Christian Ovesen; Anders F. Christensen; Derk Krieger; Sverre Rosenbaum; Inger Havsteen; Hanne Christensen

Background and Purpose— Early hematoma expansion (EHE) in patients with intracerebral hematoma is a promising treatment target. To date, the time course of EHE has remained poorly described. We prospectively investigated the time course of EHE. Methods— We included consecutive patients presenting spontaneous intracerebral hematoma within 4.5 hours. On admission, patients underwent noncontrast computed tomography (CT) and CT angiography. Serial hematoma volume estimations by transcranial B-mode ultrasound were effected through the contralateral transtemporal bone window by obtaining sagittal, transversal, and coronal diameter and calculating the ABC/2-formula. National Institute of Health Stroke Scale and transcranial B-mode ultrasound were performed consecutively every 30 minutes during the first 6 hours and from 6 to 12 hours every 2 hours. Follow-up CT and ultrasound were performed after ≈24 hours. Results— Twenty-five patients with intracerebral hematoma were included; mean (SD) time from onset to CT was 108.6 (45.7) minutes. Ten (40%) patients had EHE. In patients with a final clinically significant hematoma expansion >12.5 mL, all EHE occurred within 6 hours after admission scan. EHE in spot sign positive patients continued during the first 5 hours after CT angiography. In spot sign–negative patients, no significant EHE was observed (Friedman test, P=0.476). Neurological deterioration occurred in 5 (20%) patients and was well temporally correlated with EHE. Transcranial B-mode ultrasound demonstrated good volume estimation compared with the follow-up CT with a maximum absolute volume deviation within 7 mL and minimal systematic error (mean deviation, 1.3 [confidence interval, −0.1 to 2.6] mL). Conclusions— EHE was reliably reflected by transcranial B-mode ultrasound and mainly occurred within the first 7 to 8 hours after symptom onset. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01472224.


Cerebrovascular Diseases | 2014

Showing no spot sign is a strong predictor of independent living after intracerebral haemorrhage.

Inger Havsteen; Christian Ovesen; Anders F. Christensen; Christine Krarup Hansen; Jens Kellberg Nielsen; Hanne Christensen

Background: A spot sign on computed tomography angiography (CTA) is a potentially strong predictor of poor outcome on ultra-early radiological imaging. The aim of this study was to assess the spot sign as a predictor of functional outcome at 3 months as well as long-term mortality, with a focus on the ability to identify patients with a spontaneous, acceptable outcome. Methods: In a prospective, consecutive single-centre registry of acute stroke patients, we investigated patients with spontaneous intracerebral haemorrhage (ICH) admitted within 4.5 h after symptom onset from April 2009 to January 2013. The standard work-up in our centre included CTA for spot sign status, unless a contraindication was present. Modified Rankin Scale (mRS) scores were assessed at 3 months in the outpatient clinic or by telephone interviews. Long-term mortality was assessed by electronic chart follow-up for up to 1,500 days. Results: Of the 128 patients, 37 (28.9%) had a spot sign on admission CTA. The presence of a spot sign was associated with larger median admission haematoma volume [38.0 ml (IQR 18.0-78.0) vs. 12.0 ml (5.0-24.0); p < 0.0001] and higher median National Institutes of Health Stroke Scale score [19 (IQR 12-23) vs. 12 (6-16); p < 0.0001]. Three months after stroke, the median functional outcome was considerably better in patients without spot sign [mRS score 3 (IQR 2-4) vs. 6 (4-6); p < 0.0001]. The absence of a spot sign showed a sensitivity and specificity for good outcome (mRS scores 0-2) of 0.91 and 0.36, respectively. The presence of a spot sign was, in multivariate models, an independent inverse predictor of good 3-month outcome (OR 0.17; 95% CI: 0.03-0.88) as well as a prominent independent predictor of poor 3-month outcome (mRS scores 5-6; OR 3.40; 95% CI: 1.10-10.5) and death during follow-up (HR 3.04; 95% CI: 1.45-6.34). Patients with a spot sign surviving the acute phase had long-term survival comparable to patients with no spot sign. Conclusion: The absence or presence of a spot sign is a reliable ultra-early predictor of long-term mortality and functional outcome in patients with spontaneous ICH.


Diseases of The Colon & Rectum | 2009

Interobserver and Intraobserver Variation of Two-Dimensional and Three-Dimensional Anal Endosonography in the Evaluation of Recurrent Anal Cancer

Anders F. Christensen; Bo Nyhuus; Michael B. Nielsen

PURPOSE: This study was designed to evaluate the interobserver and intraobserver agreement of two-dimensional (2-D) and three-dimensional (3-D) anal endosonography for the detection of local recurrence anal carcinoma. METHODS: Thirty-six patients were treated for anal carcinoma, and seven had recurrent disease. They were investigated by using 3-D endosonography at Rigshospitalet from July 2001 to January 2005 because of suspected local recurrence. The 3-D endosonographic examinations were reviewed from the hard disc by two observers who twice reviewed all 2-D examinations (the axial projection) as well as all 3-D examinations (the axial, as well as the reconstructed coronal and sagittal projections). The observers scored each examination according to the following scale regarding presence of local recurrence: 1 = no finding/benign findings; 2 = properly benign findings; 3 = suspicious findings/malignant findings. Kappa statistic-statistic was used to evaluate interobserver and intraobserver variation. RESULTS: Three-dimensional endosonography achieved better interobserver agreement than 2-D endosonography: kappa 3-D 0.34-047 vs. kappa 2-D 0.15-0.28 and better intraobserver agreement: kappa 3-D 0.34-0.62 vs. kappa 2-D 0.22-0.28. These differences showed P < 0.05. CONCLUSIONS: Three-dimensional endosonography proved to have significantly better interobserver and intraobserver agreement than 2-D endosonography concerning detection of recurrent anal cancer. Three-dimensional endosonography seems to be less dependent of the individual examiner than 2-D endosonography.


Regional Anesthesia and Pain Medicine | 2014

Ultrasound-guided single-penetration dual-injection block for leg and foot surgery: a prospective, randomized, double-blind study.

Jens Børglum; Johansen K; Christensen; Lenz K; Bendtsen Tf; Tanggaard K; Anders F. Christensen; Bernhard Moriggl; Kenneth Jensen

Background and Objectives We describe a new approach to blocking the sciatic and saphenous nerves in the proximal thigh (level of the lesser trochanter or immediately below) using a single-penetration dual-injection (SPEDI) technique. The popliteal-sciatic approach necessitates repositioning of the leg exposing the popliteal fossa and an extra injection for the saphenous nerve (SAN) block at the midthigh level. We introduce an alternative, effective, and possibly faster method. Methods Sixty patients undergoing leg and foot surgery under general anesthesia were included. We deposited 15 mL of ropivacaine 0.75% around the sciatic nerve (SCN) and 5 mL of ropivacaine 0.75% at the SAN. Patients were randomized to the popliteal-sciatic/saphenous technique or the SPEDI technique. The primary outcome measure was performance time. Positioning time, pain assessment, nausea in the postanesthesia care unit, sufentanil demand, dermatomal anesthesia, and degree of motor blockade were also recorded. Results Performance time was significantly faster with the SPEDI technique (median time, 110 seconds [range, 57–315 seconds] vs 246 seconds [range, 163–472 seconds]; P < 0.0001). Positioning time was significantly shorter with the SPEDI technique (P < 0.0001). No other statistically significant differences were recorded. Conclusions The SPEDI block resulted in significantly faster performance time and reduced positioning time with statistically equal efficacy in relation to pain assessment, nausea, sufentanil demand, dermatomal anesthesia, and motor blockade. The SPEDI block is statistically an equally effective alternative to the traditional popliteal-sciatic/saphenous block combination for leg and foot surgery, but it is faster, requires only 1 skin penetration, and does not require repositioning of the leg.


Acta Radiologica | 2008

Three-dimensional endoluminal ultrasound-guided interstitial brachytherapy in patients with anal cancer:

Anders F. Christensen; Bachmann M. Nielsen; S. A. Engelholm

Background: New techniques using image guidance other than computed tomography (CT) and traditional two-dimensional (2D) endosonography might improve interstitial brachytherapy in patients with anal cancer. Purpose: To investigate a new technique guided by three-dimensional (3D) endosonography used in our institution. Material and Methods: Seventeen patients with anal carcinoma were referred to interstitial brachytherapy under 3D endosonographic guidance after external radiotherapy. The procedure was initiated by anal endosonography performed with a 10-MHz rotating endoprobe. Cross-sectional images of the anal sphincters were stored on a 3D system during retraction of the endoprobe through the anal canal. Afterward, any projection could be reconstructed. From this scanning, the optimal positioning of the needles was determined. The needles were inserted through holes in an externally fixated anal template. A repeated endosonography assured that optimal tumor coverage could be obtained by adjusting the number, dwell positions, and/or position of the needles. Results: In all patients, endosonography was able to visualize the extension of the tumors and the position of each needle in 3D. Conclusion: 3D endosonography guidance of interstitial brachytherapy in anal carcinoma seems to optimize the implant procedure and offer better information for dose planning.


Skeletal Radiology | 2018

Reliability of standing weight-bearing (0.25T) MR imaging findings and positional changes in the lumbar spine

Bjarke Brandt Hansen; Philip Hansen; Anders F. Christensen; Charlotte Trampedach; Zoreh Rasti; Henning Bliddal; Mikael Boesen

ObjectiveTo test the reliability and absolute agreement of common degenerative findings in standing positional magnetic resonance imaging (pMRI).Methods and materialsLow back pain patients with and without sciatica were consecutively enrolled to undergo a supine and standing pMRI. Three readers independently evaluated the standing pMRI for herniation, spinal stenosis, spondylolisthesis, HIZ lesions and facet joint effusion. The evaluation included a semi-quantitative grading of spinal stenosis, foraminal stenosis and spinal nerve root compression. The standing pMRI images were evaluated with full access to supine MRI. In case lower grades or the degenerative findings were not present in the supine images, this was reported separately as position-dependent changes. A subsample of 20 pMRI examinations was reevaluated after two months. The reproducibility was assessed by inter- and intra-reader reliability (kappa statistic) and absolute agreement between readers.ResultsFifty-six patients were included in this study. There was fair-to-substantial inter-reader reliability (κ 0.47 to 0.82) and high absolute agreement (72.3% to 99.1%) for the pMRI findings. The intra-reader assessment showed similar reliability and agreement (κ 0.36 to 0.85; absolute agreement: 62.5% to 98.8%). Positional changes between the supine and standing position showed a fair-to-moderate inter- and intra-reader reliability (κ 0.25 to 0.52; absolute agreement: 97.0% to 99.1).ConclusionEvaluation of the lumbar spine for degenerative findings by standing pMRI has acceptable reproducibility; however, positional changes from the supine to the standing position as an independent outcome should be interpreted with caution because of lower reliability, which calls for further standardisation.

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Inger Havsteen

Copenhagen University Hospital

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Jens Børglum

University of Copenhagen

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Kenneth Jensen

Copenhagen University Hospital

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Michael B. Nielsen

Copenhagen University Hospital

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Charlotte Trampedach

Copenhagen University Hospital

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Christine Krarup Hansen

Copenhagen University Hospital

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