Biomedical subjects

P Reinartz

Publications and source records attributed to P Reinartz.

24 records · Page 2Linked to original sources

PubMed1999

F-18-FDG positron imaging in oncological patients: gamma camera coincidence detection versus dedicated PET.

AIM: Of the present study was to investigate the feasibility of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) imaging in oncological patients with a dual head gamma camera modified for coincidence detection (MCD). METHODS: Phantom studies were done to determine lesion detection at various lesion-to-background ratios, system sensitivity and spatial resolution. Thirty-two patients with suspected or known malignant disease were first studied with a dedicated full-ring PET system (DPET) applying measured attenuation correction and subsequently with an MCD system without attenuation correction. MCD images were first interpreted without knowledge of the DPET findings. In a second reading, MCD and DPET were evaluated simultaneously. RESULTS: The phantom studies revealed a comparable spatial resolution for DPET and MCD (5.9 x 6.3 x 4.2 mm vs. 5.9 x 6.5 x 6.0 mm). System sensitivity of MCD was less compared to DPET (91 cps/Bq/ml/cmFOV vs. 231 cps/Bq/ml/cmFOV). At a lesion-to-background ratio of 4:1, DPET depicted a minimal phantom lesion of 1.0 cm in diameter, MCD a minimal lesion of 1.6 cm. With DPET, a total of 91 lesions in 27 patients were classified as malignant. MCD without knowledge of DPET results revealed increased FDG uptake in all patients with positive DPET findings. MCD detected 72 out of 91 DPET lesions (79.1%). With knowledge of the DPET findings, 11 additional lesions were detected (+12%). MCD missed lesions in six patients with relevance for staging in two patients. All lesions with a diameter above 18 mm were detected. CONCLUSION: MCD FDG imaging yielded results comparable to dedicated PET in most patients. However, a considerable number of small lesions clearly detectable with DPET were not detected by MCD alone. Therefore, MCD cannot yet replace dedicated PET in all oncological FDG studies. Further technical refinement of this new method is needed to improve image quality (e.g. attenuation correction).

Adult↗

PubMed1999

[Various dynamics of Tc-99m-tetrofosmin and Tc-99m-MIBI in a parathyroid adenoma].

Case report of a patient with hypercalcemia and suspected parathyroid adenoma. Because of a previous strumectomy a precise preoperative localization of the suspected parathyroid adenoma was demanded. Tc-99m-tetrofosmin scintigraphy in double phase technique failed to detect a parathyroid adenoma by failing to show a region of increased focal uptake with delayed washout in relation to the thyroid gland. Only comparison of the Tc-99m-tetrofosmin images with a Tc-99m-pertechnetate scan revealed a right caudal parathyroid adenoma. A double phase Tc-99m-MIBI study of the same patient was able to localize this parathyroid adenoma without the need of a corresponding Tc-99m-pertechnetate scintigraphy due to a differential washout with persistent focal uptake in the parathyroid adenoma and a progressively decreasing uptake in the thyroid tissue. This case indicates that Tc-99m-tetrofosmin is a suitable agent for parathyroid imaging only if used together with Tc-99m-pertechnetate but it seems to lack the differential washout characteritics of Tc-99m-MIBI according parathyroid gland and thyroid gland.

Adenoma↗

PubMed1999

[Quantification of repositioning errors in PET studies through superimposition of emission and transmission scans. Comparison between acquisition with and without repositioning].

AIM: The purpose of this study was to quantify positioning discrepancies between emission (E) and transmission (T) scan using image fusion. A direct comparison of one-step and two-step acquisitions was performed where all studies were analyzed in respect to artifacts caused by inaccurate positioning. In addition, phantom measurements were conducted to estimate the consequences of repositioning errors on standardized uptake value calculations (SUV). METHODS: 40 patients were examined by two-step whole-body scans using PET and 15 patients were subject to one-step examinations in the head/neck area. Repositioning between the scans was achieved by a laser matrix positioning system in combination with external body markings. After reconstruction and image fusion of the scans, the positioning discrepancies were measured as the distances between the outer boundaries of E and T in four different body regions. Additional evaluations of the SUV by increasing E-T dislocation were performed using a Jaszczak phantom containing hollow spheres. RESULTS: For the two-step acquisitions, the mean spatial deviations along the three orthogonal axes x, y, and z were between 8.9 mm and 13.8 mm, whereas for the one-step examinations mean values between 3.5 mm and 4.3 mm were determined (level of significance in each direction p < 0.0001). Artifacts were found in 47.5% of the whole body scans, but in none of the head/neck studies. The development of image artifacts was simulated by phantom studies. In contrast, the deviations of the computed SUV caused by increasing positioning discrepancies were minimal because of the minimal differences between the attenuation coefficients of the media involved. CONCLUSION: The presented data show that an artifactfree reconstruction of attenuation-corrected studies requires a precise positioning of the patient. One-step examination protocols without repositioning are advantageous due to the significantly lower positioning discrepancies. The additional reconstruction of nonattenuation-corrected studies has proven to be useful in discovering image artifacts and is therefore recommended.

Artifacts↗

PubMed1999

Diagnostic evaluation of malignant head and neck cancer by F-18-FDG PET compared to CT/MRI.

AIM: Evaluation of F-18-FDG PET in comparison to CT/MRI as diagnostic tool in primary and recurrent head and neck cancer. METHODS: 78 F-18-FDG PET studies were performed in 71 patients with known or suspected primary (n = 48) or recurrent (n = 30) head and neck cancer and compared to CT (n = 75) or MRI investigations (n = 3) concerning detection of the primary or recurrent tumor and detection of regional lymph node metastases in the ipsilateral and contralateral neck sides. Glucose uptake (SUV) of PET findings was correlated to tumor location, grading and dignity of the lesion. RESULTS: Sensitivity and specificity for PET in detection of primary tumors were 87%* and 67%, respectively (CT/MRI 67%* and 44%) (*p < 0.05), in detection of local recurrence 86% and 75%, respectively (CT/MRI 57% and 92%), in detection of necks affected by lymph node metastases 80% and 92%, respectively (CT/MRI 80% and 84%). Laryngeal, buccal (cheek) and salivary gland tumors had significant lower glucose uptake (SUV) when compared to tumors of the hypopharynx (p < 0.05). G1-tumors (mean SUV 4.26) had significant (p < 0.05) lower glucose uptake when compared to G2- and G3-tumors (mean SUV 7.73 and 8.19, respectively). Mean SUV of malignant PET findings (7.88) was significant (p < 0.05) higher than mean SUV of benign PET findings (5.70). However, a SUV threshold to improve diagnostic accuracy could not be defined. CONCLUSIONS: F-18-FDG PET is significantly more accurate than CT/MRI for detection of head and neck cancer. Both methods are valuable for detection of cervical lymph node metastases. Glucose uptake shows correlation to histological grading. A quantitative SUV analysis does not improve diagnostic accuracy.

Female↗

PubMed1999

[Radioiodine therapy in veterinary medicine: treatment of hyperthyroidism in a cat].

A nine-year-old cat with symptoms of a distinct hyperthyroidism was presented at the University Hospital of the RWTH Aachen. The clinical symptoms as well as the diagnostic procedures performed at the hospital confirmed the diagnosis. After five weeks of thyreostatic medication a regular metabolism of the thyroid gland was established, followed by a radioiodine therapy with 70.3 MBq 131-iodine. Subsequently, the cat was hospitalized for two days before it could be released in good condition. Six weeks after treatment the former drastically reduced weight of the cat recovered to near normal. Even though the chemical analysis detected a discrete hyperthyroidism, clinical symptoms were no longer prominent. Three months after treatment, the final examination showed a regular metabolism of the thyroid gland without a specific thyroidal medication. The presented case illustrates that radioiodine therapy is a safe and efficient treatment of thyroidal dysfunctions in veterinary medicine.

Animals↗

PubMedDate not supplied

[[F-18]-fluorodeoxyglucose (FDG) positron emission tomography (PET) as a diagnostic for hip endoprosthesis loosening].

AIM: The purpose of this study was to examine the FDG-PET in respect of its diagnostic valency with regard to septic/aseptic loosening of lower limb prostheses. METHOD: 28 patients with 41 lower limb prostheses were examined by means of FDG-PET to evaluate septic/aseptic loosening of their hip prostheses. Therefore, a differentiated FDG-PET result interpretation subdivided into five categories was developed. The final diagnosis was based on operative findings with following culture and histological outcome. RESULTS: The worked-out categories showed a high agreement to the intraoperative macroscopic and histological results (n = 23 correctly positive, n = 1 false positive, n = 1 correctly negative and n = 3 false negative). CONCLUSION: With a subtly differentiated interpretation (categories I - V) of the qualitative glucose metabolism safe statements can be made regarding septic/aseptic endoprostheses loosening. This was impressively confirmed by the agreement of the FDG results with the histological results.

Aged↗