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T Helmberger

Publications and source records attributed to T Helmberger.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Techniques and applications of MR pancreatography in comparison with endoscopic retrograde pancreatography].

Using heavily T2 weighted sequences, magnetic resonance tomography allows the delineation of the pancreatic duct system with high contrast. The development of fast and ultrafast imaging sequences results in a variety of different technical approaches already published. Aim of this article is the review of the different approaches and results published. In addition, we compare MRP in 34 patients with results of ERP using a snap-shot sequence approach. In this study, MRP has a sensitivity of 83.3% a specifity of 90.9% and accuracy of 83.3% regarding detection of duct changes like stenosis, occlusion and duct dilatation. Our results indicate, that MR-pancreaticography can be a valuable adjunct to MR-imaging of the pancreas.

Adult↗
PubMed1996

[Initial experiences with pulsed fluoroscopy on a multifunctional fluoroscopic unit].

PURPOSE: Comparison of radiation doses in pulsed and continuous fluoroscopy to quantify the dose reduction by pulsed fluoroscopy. Further, the applicability of pulsed fluoroscopy in clinical routine has been evaluated. MATERIALS AND METHODS: In a human pelvic phantom, the radiation dose (skin entry dose in cGycm2) was measured at two pulses per second (pps), 3 pps, 6 pps, 12 pps and continuous fluoroscopy mode, respectively, using image-intensifier entries of 38 cm, 25 cm, and 17 cm. 300 examinations were carried out, and the results of the different fluoroscopy modes were registered. RESULTS: Dose reduction depends on the image-intensifier entry. Compared to the radiation dose in continuous fluoroscopy, with 12 pps fluoroscopy the radiation dose can be reduced at a minimum of 51%, with 6 pps fluoroscopy to 40%, with 3 pps fluoroscopy to 20%, and with 2 pps fluoroscopy to a minimum of 14.5%. Clinical routine has shown that 78% of all examinations can be performed with 2 or 3 pps fluoroscopy mode. In 12.7% of the cases pulsed fluoroscopy of diverse frequencies was used, in an additional 2% combined with continuous fluoroscopy. Exclusively, continuous fluoroscopy has been employed in 2% of the cases. CONCLUSIONS: Using pulsed fluoroscopy, an 80% reduction of the radiation dose compared to continuous fluoroscopy is possible. About 96% of all examinations can be performed with pulsed fluoroscopy of different pulse rate and without using continuous fluoroscopy.

Diagnostic Tests, Routine↗
PubMed1996

Ring enhancement in ultrasmall superparamagnetic iron oxide MR imaging: a potential new sign for characterization of liver lesions.

OBJECTIVE: We performed this study to evaluate the incidence and significance of ring enhancement after i.v. administration of an ultrasmall superparamagnetic iron oxide (USPIO) particle (Code 7227), a reticuloendothelial contrast agent with potential use as a blood-pool agent, for characterizing focal hepatic lesions. SUBJECTS AND METHODS: Conventional T1-weighed imaging, fat-suppressed T1-weighted imaging, conventional T2-weighted imaging, and fast T2-weighted imaging of the liver were obtained in 27 patients with 43 liver lesions before and after i.v. administration of a USPIO preparation. All lesions were larger than 1 cm; 29 were malignant and 14 were benign. Diagnosis was confirmed in all cases, either pathologically (19 patients) or by follow-up examination (eight patients). Two readers independently evaluated each pulse sequence for the presence of ring enhancement of hepatic lesions. RESULTS: Ring enhancement was noted only on T1-weighted images, with no ring enhancement evident on T2-weighted images. Twenty of 43 (47%) lesions showed ring enhancement, including 18 of 29 (62%) malignant lesions and two of 14 (14%) benign lesions (p < .011); Wilcoxon signed rank test). Fat-suppressed T1-weighted imaging showed ring enhancement better than or equal to conventional T1-weighted imaging in all cases, with ring enhancement of 15 of 18 (83%) malignant lesions and two of two benign lesions better demonstrated on fat-suppressed T1-weighted imaging sequences (p < or = .025). CONCLUSION: Ring enhancement after i.v. administration of Code 7227 is a frequent finding seen more often with malignant than benign lesions, potentially identifying a new MR imaging feature for the characterization of liver lesions. The identification of ring enhancement on T1-weighted images attests to the significant blood-pool effects of USPIO particles.

Contrast Media↗
PubMed1995

[Phased-array superficial coil and breath holding technique in MRI of the liver. Comparison of conventional spin echo sequences with rapid fat suppressing gradient echo and turbo-spin sequences].

PURPOSE: To determine the efficacy of fast MRI techniques using a tailored imaging design (breathhold and array-surface coil), conventional T1-, T2-weighted spin-echo (SE) sequences and breathhold gradient-echo (GRE) T1- and breathhold fast SE T2-weighted images were compared. METHODS: 20 patients with proven focal liver lesions were studied on a 1.5 Tesla system. Conventional SE T1- and T2-weighted imaging, as well as GRE T1- and fast SE T2-weighted imaging was performed. Fast imaging was done during breathhold using an array-surface coil. For all sequences signal-to-noise ratios (S/N) and liver-to-lesion-contrast ratios (L/L) were measured and statistically compared. In addition, two blinded readers qualitatively evaluated all images, using a score system regarding artifacts (breathing, pulsation), number of lesions, and over-all image quality. RESULTS: Regarding image quality parameters, S/N and L/L, there was no significant (p > 0.05) difference between the conventional and fast imaging techniques. However, GRE imaging was superior (84.8%) to conventional imaging for breathing and pulsation artifacts, while fast SE T2 imaging was equal regarding breathing artifacts, but superior (51.5%) regarding pulsation artifacts. The number of detected hepatic lesions was identical in all sequences. CONCLUSION: The fast MRI techniques demonstrated a superiority to conventional imaging regarding image quality and presence of artifacts. Therefore, fast imaging techniques can replace conventional techniques, at least in patients that can sufficiently sustain breathing.

Artifacts↗
PubMed1994

True proton density and T2-weighted turbo spin-echo sequences for routine MRI of the brain.

Our aim was to evaluate the diagnostic reliability of turbo spin-echo (TSE) sequences compared to a conventional dual-echo spin-echo (SE) sequence in routine brain MRI at 1.0 T. The following demands were made on TSE sequences: acquisition time-reduction of at least 50% and true proton density (PD) contrast (low-signal cerebrospinal fluid). A conventional spin-echo and two single-echo TSE sequences were used in 150 patients, a dual-echo TSE sequence in addition in 50 patients. Demonstration of most anatomical structures and disorders was equivalent with TSE and SE sequences. Advantages of TSE were reduced flow artefacts on T2-weighted images, better lesion contrast on PD-weighted TSE images (especially in the dual-echo sequence) and acquisition time reduction to about 5 min (single-echo TSE) and 3:35 min (dual-echo TSE). Disadvantages of TSE were: reduced contrast of iron-containing substances such as haemosiderin and of areas of calcification. By virtue of the shorter acquisition time and diagnostic reliability dual-echo TSE proved the best sequence. If it is used with only one acquisition--whereby image quality but not diagnostic reliability is slightly decreased--acquisition time can be further reduced to 1:48 min. Application of a susceptibility-sensitive gradient-echo sequence, such as FLASH, compensates for the disadvantages mentioned above.

Artifacts↗
PubMed1994

[The multilocular occlusive form of fibromuscular hyperplasia].

The rare case of a 19-year-old man with fibromuscular hyperplasia (FMH) affecting several arteries with tubular stenosis and occlusions is presented. Involved were both internal carotid arteries, the right renal artery, celiac axis and the superior mesenteric artery. The disease pattern of FMH is discussed regarding frequency, vascular morphology and differential diagnosis.

Adult↗
PubMed1994

Unilocular toxoplasmosis simulating intracerebral tumor.

Toxoplasmosis is a common infection with increased incidence in patients suffering from AIDS. In this paper we report a rare case of toxoplasmosis without evidence of AIDS: The patient had a singular tumor-like lesion in the right parietal lobe in CT and MRI. In neurosurgical intervention no tumor was found. Finally, different histopathological examinations led to the diagnosis of toxoplasmosis. Diagnostic and therapeutic regimes in patients with suspect tumor-like lesions should be discussed.

Aged↗
PubMed1993

[Ambulant transbrachial 4-French arteriography with particular reference to the aortofemoral vascular system].

Arteriograms were carried out on 176 patients using 4-F catheters through a transbrachial approach. Criteria for exclusion from the series were injuries to the upper limb, hemiparesis or poor pulses in the presence of a normal femoral pulse. There were no local vascular complications requiring treatment. On two occasions the brachial artery could not be punctured. Acute posterior cerebral infarction was the only serious complication (0.5%). 67% of the patients were examined on an outpatient basis and this did not appear to increase the risk of complication. We regard this as a suitable method for demonstrating the pelvic and lower limb arteries on ambulant patients.

Adult↗
PubMed1991

[Arterial collateral pathways in liver cirrhosis and celiac axis occlusion].

We describe the arterial supply in a patient with cirrhosis of the liver, occlusion of the coeliac axis and with a replaced right hepatic artery from the superior mesenteric artery. Six arterial pathways between the mesenteric and hepatosplenic axis were demonstrated, and hepatofugal blood flow was shown in spite of coexistent portal hypertension.

Arterial Occlusive Diseases↗