[Comparison of conventional full spine radiographs and fluoroscopic scanning method in young patients with idiopathic scoliosis]

PURPOSE

Evaluation of low-dose full spine radiographs using fluoroscopic images for the assessment of the Cobb angle measurement in patients with scoliosis.

MATERIAL AND METHODS

Twenty-one consecutive patients (aged 10 - 27 years, mean age 14 years) with a conventional full spine examination (film speed class 800) underwent a follow-up exam using digital pulsed fluoroscopy (Multi Diagnost 4, Philips Medical Systems, Eindhoven, The Netherlands). The mean follow-up was 9 months. During a synchronized scan with a C-arm speed of 4 cm/sec fluoroscopic images were stored with a pulsed frequency of 3 images per second. The single images were merged and reconstructed to one image with the software Easy Spine (Philips medical Systems, Eindhoven, The Netherlands). The corresponding dose-area product values (DAP) of both methods were compared. Three independent observers assessed Cobb angles and image quality for each technique.

RESULTS

The mean DAP values for conventional imaging was 94.9 cGy x cm (2) and for fluoroscopy 7.8 cGy x cm (2), respectively. A significant dose reduction of 91.8 % (CI 91 % to 95 %) was calculated. The average absolute angle difference between the observers was found to be 2.7 degrees for conventional imaging and 2.4 degrees for the fluoroscopic method. Interobserver standard deviation of 2.9 degrees was lower than the 5.3 degrees for conventional images. Image quality was better in the conventional images.

CONCLUSION

Using the scanning method, we could achieve a mean reduction of the radiation dose of 92 %, while the accuracy of the Cobb angle measurements was comparable for both techniques despite of reduced image quality of digital fluoroscopy.

High-resolution magnetic resonance imaging of trabecular bone in the wrist at 3 tesla: initial results

PURPOSE

To evaluate the feasibility of high-resolution magnetic resonance imaging (MRI) of trabecular bone of the wrist at 3 Tesla (3T) in vivo and to assess the potential benefit of the increased resolution for clinical assessment of structural changes in spongy bone.

MATERIAL AND METHODS

High-resolution MRI of the wrist was performed with a whole-body 3T MR scanner using a dedicated circularly polarized transmit-receive wrist-coil. Two 3D-FISP sequences with a spatial resolution of 300 x 300 x 300 microm3 in a measuring time of TA = 7:51 min, and 200 x 200 x 200 microm3 in TA = 9:33 min were applied. Seven young healthy volunteers and three elderly subjects with suspected osteoporosis were examined. The signal-to-noise ratio (SNR) in the optimized setup at 3T was compared to measurements at 1.5T.

RESULTS

The images at 3T allow microscopic analysis of the bone structure at an isotropic spatial resolution of 200 microm in examination times of <10 min. Differences in the structure of the spongy bone between normal and markedly osteoporotic subjects are well depicted. The SNR at 3T was found up to 16 times higher than at 1.5T applying unchanged imaging parameters.

CONCLUSION

The proposed high-resolution MRI technique offers high potential in the diagnosis and follow-up of diseases with impaired bone structure of hand and/or wrist in clinical applications.

Uncommon case of a foreign body ingestion with consecutive small-bowel obstruction in a child

A 12-year-old boy with Lennox syndrome presented with an acute abdomen and a history of progressive abdominal pain and vomiting over 3 weeks. The uncommon finding in this case was a foreign body detected in a lower loop of the jejunum causing radiological and clinical signs of jejunitis/ileitis. The foreign body had to be removed surgically and turned out to be a hard (originally soft) plastic part of a towel rack.

Direkte CT-Arthrographie versus direkte MR-Arthrographie bei chronischer Schulterinstabilität: Ein Methodenvergleich nach Einführung der Multidetektor-CT-Technik

PURPOSE

To evaluate the diagnostic accuracy of direct multidetector CT arthrography (CTA) and direct MR arthrography (MRA) in patients suffering from chronic shoulder instability.

MATERIALS AND METHODS

Twenty-nine patients suffering from chronic shoulder instability were included into a prospective study. In all cases, the indication for direct CTA and arthroscopy was set by the orthopedic surgeon. Prior to the imaging procedures, 10 to 20 ml of a special combination of contrast media (including saline, Isovist(R) and Magnevist(R) in a relation of 125 : 125 : 1) was injected into the joint under sterile conditions. First, CTA was performed with a multidetector CT, with images reconstructed in the axial, semi-coronal and semi-sagittal planes. Thereafter, MRA was performed. Axial images were obtained using a T1-weighted, fat-saturated spin echo sequence and semi-coronal images using a T1-weighted FLASH-3D GRE sequence. The results of CTA and MTA were compared with results obtained from arthroscopy or arthrotomy.

RESULTS

MRA was superior to CTA in the detection of labral lesions. The sensitivity of MRA was 96 % and the specificity 96 %, compared to a sensitivity of 76 % (p < 0.05) and specificity of 92 % for CTA. Both methods showed the same effectiveness concerning the assessment of capsule distension (sensitivity for both techniques: 91 %).

CONCLUSIONS

MRA seems to be superior to CTA in the diagnostic workup of chronic shoulder instability even when using a multidetector CT technique.

Experimentally induced emotions, facial muscle activity, and respiratory resistance in asthmatic and non-asthmatic individuals

We studied the effects of emotion induction on total respiratory resistance, and their relationship with cardiac vagal activity and facial muscle activity in asthma. Groups of 20 asthmatic and 20 non-asthmatic participants were exposed to series of happy and depressing pictures or self-referent Velten statements. Facial electromyographic activity over corrugator supercilii, orbicularis oculi, and zygomaticus major regions was recorded during periods of presentation and imagery of each stimulus. Following each stimulus series, mood, respiratory resistance, ventilation, and cardiac activity including respiratory sinus arrhythmia (RSA) were recorded. Significant increases of respiratory resistance were observed in asthmatic patients following depressing stimulation. Resistance increases were positively correlated with RSA and heart period. No substantial group differences were found in facial response to emotional stimuli. Changes in facial target muscle sites during positive stimulation were inversely correlated with RSA following stimulation. We conclude that respiratory resistance increases in asthmatics following depressing stimulation are dependent on vagal activity. Greater facial muscle activation during emotional stimulation can reduce vagal activation, which is consistent with claims in the clinical literature of the benefits of emotional expression in asthma.

Focal liver lesions: evaluation of the efficacy of gadobenate dimeglumine in MR imaging--a multicenter phase III clinical study

PURPOSE

To evaluate gadobenate dimeglumine (Gd-BOPTA) for dynamic and delayed magnetic resonance (MR) imaging of focal liver lesions.

MATERIALS AND METHODS

In 126 of 214 patients, MR imaging was performed before Gd-BOPTA administration, immediately after bolus administration of a 0.05- mmol/kg dose of Gd-BOPTA, and 60-120 minutes after an additional intravenously infused 0.05-mmol/kg dose. In 88 patients, imaging was performed before and 60-120 minutes after a single, intravenously infused 0.1-mmol/kg dose. T1- and T2-weighted spin-echo and T1-weighted gradient-echo images were acquired. On-site and blinded off-site reviewers prospectively evaluated all images. Intraoperative ultrasonography, computed tomography (CT) during arterial portography, and/or CT with iodized oil served as the reference methods in 110 patients.

RESULTS

Significantly more lesions were detected on combined pre- and postcontrast images compared with on precontrast images alone (P <. 01). All reviewers reported a decreased mean size of the smallest detected lesion and improved lesion conspicuity on postcontrast images. All on-site reviewers and two off-site reviewers reported increased overall diagnostic confidence (P <.01). Additional lesion characterization information was provided on up to 109 (59%) of 184 delayed images and for up to 50 (42%) of 118 patients in whom dynamic images were assessed. Gd-BOPTA would have helped change the diagnosis in 99 (47%) of 209 cases and affected patient treatment in 408 (23%) of 209 cases.

CONCLUSION

Gd-BOPTA increases liver lesion conspicuity and detectability and aids in the characterization of lesions.

Correlation of imaging techniques to histopathology in patients with diabetic foot syndrome and clinical suspicion of chronic osteomyelitis. The role of high-resolution ultrasound

OBJECTIVE

To investigate the role of ultrasound in the diagnosis of osteomyelitis in the diabetic foot compared with magnetic resonance imaging (MRI), bone scintigraphy (BS), and plain film radiography (PFR).

RESEARCH DESIGN AND METHODS

We investigated 19 consecutive diabetic patients (2 women, 17 men, age 60.7 +/- 9.8 years, BMI 27.0 +/- 3.8 kg/m2) with clinical suspicion of bone infection of the foot. A high-resolution ultrasound system (Esaote/Biosound, Munich) with a linear array transducer up to 13.0 MHz was used. The prospective and blinded results of each method were compared with histopathology as the reference method after metatarsal resection.

RESULTS

In 14 of 19 patients, histopathology confirmed osteomyelitis. Ultrasound showed a sensitivity of 79% (PFR, 69%; BS, 83%; MRI, 100%), a specificity of 80% (PFR, 80%; BS, 75%; MRI, 75%), a positive predictive value of 92% (PFR, 90%; BS, 91%; MRI, 93%), and a negative predictive value of 57% (PFR, 50%; BS, 60%; MRI, 100%).

CONCLUSIONS

Our data indicate that ultrasound might have a better diagnostic power for detecting chronic osteomyelitis in the diabetic foot than PFR and has similar sensitivity and specificity as BS. MRI is superior to the other three methods. We conclude that the use of ultrasound in the management of the diabetic foot is worthy of further investigation.

Gadopentetate dimeglumine as a bowel contrast agent: safety and efficacy

To determine the safety and efficacy of gadopentetate dimeglumine as a bowel contrast agent, magnetic resonance (MR) imaging (0.5 T) was performed with a formulation of gadopentetate dimeglumine (1.0 mmol/L of gadopentetate dimeglumine, 15 g/L of mannitol, 6-17 mL/kg) in 133 patients with intraabdominal mass lesions. Mostly short-lived gastrointestinal side effects were noted in 32% of patients. Gadopentetate dimeglumine provided uniform hyperintense marking of the bowel and contrast enhancement in the region of interest in 81% of patients. Among 78 patients with images obtained both before and after administration of contrast material, post-contrast improvement of lesion delineation was found in 62%. Among 55 patients with only postcontrast images, gadopentetate dimeglumine proved useful in 65%. Intravenous injection of scopolamine or glucagon effectively eliminated "ghost" images of the opacified bowel in 105 of 109 cases. The authors conclude that gadopentetate dimeglumine is a safe and effective bowel contrast agent for MR imaging.

Lesions of skull base observed on high resolution computed tomography. A comparison with magnetic resonance imaging

Forty patients with tumors involving the skull base were selected on the basis of findings at high resolution computed tomography (CT). The reliability of demonstrating bony lesions with magnetic resonance imaging (MRI) and CT were compared. CT showed osseous lesions of the skull base better than MRI but was less sensitive in evaluating an associated inflammatory reaction or in defining intracerebral infiltration. Small cortical lesions were only demonstrable with CT. MRI was superior in defining the full extent of soft tissue infiltration. Arterial encasement was observed at MRI. The special advantage of Gd-DTPA lies in the additional possibility to differentiate vessels from tumor-like lesions and in en plaque tumors.

[Scrotal changes in the 3.5 MHz ultrasound image]

Sonography enables sensitive detection of pathological changes in the scrotum, since the planes of intersection can be selected as may be required, and since local resolution is excellent. However, sonographic criteria alone do not permit differential diagnosis of malignomas against benign changes. Anamnesis and clinical examination are of equal importance as sonography. Diagnostic conclusions are possible only if all the findings based on all the diagnostic approaches are combined in synopsis. Although reports published in recent years postulated transducer either of a frequency higher than 3.5 mHz (1, 5, 11, 12, 13, 14, 17, 20, 21, 24, 25, 27) or low-frequency transducers associated with immersion technique (7, 23), in our patients the use of a 3.5 mHz convex scanner with water forerun resulted always in confirming the diagnosis (in conjunction with anamnesis and clinical findings). In our experience a transducer of this frequency (3.5 mHz) with water forerun appears to be suitable for routine diagnosis of changes in the scrotum. This is an important aspect in general practice, where ultrasound equipment is often fitted with 3.5 mHz transducers.

[Oral contrast media for magnetic resonance tomography of the abdomen. III. Initial patient research with gadolinium-DTPA]

32 patients with abdominal tumours or inflammatory abdominal diseases were examined by MRI (0.5 T) prior to and after oral administration of gadolinium-DTPA (Gd-DTPA). T1- and T2-weighted sequences were employed. 10 ml/kg body weight of a Gd-DTPA formulation were administered (1.0 mmol/l, 15 g mannitol/l). Gd-DTPA provided markedly hyperintensive opacification of the gastrointestinal tract. In 19 of 32 studies Gd-DTPA-enhanced scans showed improved delineation of abdominal pathologies. In most cases Gd-DTPA-enhanced T1-weighted multislice gradient echo images provided the most useful diagnostic result. Meteorism and diarrhea were recorded in 13 patients.

CT reconstruction technique in lumbar intraneuroforaminal disc herniation

The CT appearance of the lumbar neural foramina and contents is described in detail and compared to histopathological specimens. Direct axial scans with secondary sagittal, coronal and paraxial reconstruction series of slices of the neural foramen were derived from lumbar spine examination of fifty normal adults. These normal parameters were then used to evaluate and subdivide 20 patients with disc herniation involving the neural foramen. The new paraxial reformation was able to show an intraneuroforaminal disc involvement. CT-reformation technique and operative results in intraneuroforaminal disc herniation correspond in 80%. This improvement in preoperative diagnosis demonstrates to the neurosurgeon the full extent of disc herniation and results in an optimized operative approach.

[Oral contrast media for magnetic resonance tomography of the abdomen. 1. Comparative animal studies of positive and negative contrast media]

Beagle dogs were investigated by MRI (Siemens Magnetom, 0.35 T) after oral administration of aqueous solutions of Gd-DTPA (n = 4), ferric ammonium citrate (n = 1), and magnetite dextran (n = 2). High signal intensity of the GI-tract versus adjacent structures was obtained with Gd-DTPA and ferric ammonium citrate. Magnetite showed negative contrast versus adjacent structures. However, magnetite displayed lower contrast relative to liver, muscle and gut wall compared to Gd-DTPA and ferric ammonium citrate. In relatively T2-weighted sequences labeling of poorly filled bowel loops was significantly better with Gd-DTPA and ferric ammonium citrate. For GI-tract contrast enhancement we conclude that positive contrast media are of higher diagnostic value compared to negative contrast agents.