CT number variations due to different image acquisition and reconstruction parameters: a thorax phantom study.

A humanoid thorax phantom containing six compartments was scanned with two different computed tomography (CT) scanners using various image acquisition and reconstruction parameters. The differences of CT numbers were statistically significant between the two CT scanners for each compartment (p<0.001) except for the "air" compartment. The variabilities of the CT numbers are described for the different parameters. The mean CT numbers of the "water" compartment, for instance, ranged from 1 to 15HU (Hounsfield Units), those of the "air" compartment varied from -962 to -990HU. Knowledge of these CT number variabilities is necessary when CT numbers are used for tissue characterization.

Contrast-enhanced spiral CT of the head and neck: comparison of contrast material injection rates.

BACKGROUND AND PURPOSE: Contrast-enhanced spiral CT studies of the head and neck are performed frequently using contrast material volumes of approximately 30 g iodine and a scan delay of 30-45 seconds. Because little is known about the effects of contrast material injection rates on tissue enhancement, this was prospectively investigated in our study. METHODS: Ninety-seven patients underwent spiral CT of the head and neck. Each patient was assigned randomly to one of four groups who received 100 mL of nonionic contrast material (300 mg I/mL) at different monophasic injection flow rates with 1.5, 2, 3, and 4 mL/s. Scanning started after a constant delay of 35 seconds. The attenuation of the carotid artery, jugular vein, and sternocleidomastoid muscle was measured over time and the attenuation of the submandibular and thyroid gland was evaluated. Vascular attenuation of at least 150 HU was considered to be sufficient. RESULTS: The mean scan time was 33+/-5 seconds. The study, using an injection rate of 2 mL/s, showed the longest time of sufficient overall (arterial and venous) vessel attenuation (27+/-4 seconds, P< or =.008). The injection flow rate did not influence significantly muscular attenuation (mean enhancement during scan time: 9+/-7 HU). The 1.5 mL/s protocol showed the lowest attenuation values of the submandibular gland (81+/-12 HU) and the highest attenuation values of the thyroid gland (164+/-22 HU), but the attenuation of the thyroid gland was not statistically different from that revealed by the 2 mL/s protocol. CONCLUSION: Using 100 mL of intravenous contrast material with 300 mg I/mL for spiral CT studies of the entire head and neck, the optimal injection flow is 2 mL/s, whereas lower flow rates resulted in insufficient venous enhancement.

Adjuvant radiotherapy in male breast cancer.

PURPOSE: To determine retrospectively the outcome of postoperative radiation therapy in male breast cancer. Local/distant control was assessed with attention to age, stage, lymph node involvement, histopathological differentiation and hormone receptor status. MATERIALS AND METHODS: Thirty-one male patients were irradiated postoperatively at the chest wall (mean dose 50 Gy) and 16 patients received radiation to regional lymph nodes. Tumour distribution by stage was: stage 0 (9.7%), stage I (22.6%), stage II (32.2%) and stage III (35.5%). Nine patients were subjected to additional hormone therapy and three patients to chemotherapy. RESULTS: Local control was achieved in 30/31 (96.8%) patients. Kaplan-Meier estimates of overall survival (OS), disease specific (DSS) and disease free survival (DFS) at 5 years were 77% (95% confidence interval (CI), 0.61-0.93), 84% (CI, 0.69-0.98) and 73% (CI, 0.57-0.91), respectively. Five-year DFS for stage 0 + I, II and III was 100, 56.3 and 67.3%, respectively. Favourable results were observed in patients with negative axillary nodes with 5-year OS/DFS of 90.9% (CI, 0.74-1.0). For lymph node positive patients DFS was 71% (CI, 0.4-1.0). Patients who presented lymph node metastases with extracapsular extension the 5-year OS was 80% (CI, 0.45-1.00), but the DFS was 0%. Stage of disease, lymph node involvement and histological differentiation were found to have statistically significant influence on DFS, but not on OS. CONCLUSION: Application of postoperative radiotherapy approved in females resulted in one local relapse in our study population. Other treatment modalities (hormone therapy/chemotherapy) should continue to be considered a necessary treatment option for appropriately selected patients.

[The photon therapy of subfoveal choroidal neovascularization in age-dependent macular degeneration. The results of a prospective study in 40 patients]. / Photonentherapie der subfovealen choroidalen Neovaskularisation bei altersabhängiger Makuladegeneration. Ergebnisse einer prospektiven Studie an 40 Patienten.

AIM: To determine the effect of external beam radiotherapy on subfoveal choroidal neovascularization in age-related macular degeneration. PATIENTS AND METHODS: Between September 1995 and July 1996, 40 patients (9 males and 31 females; mean age 74 years, range 61 to 83 years) were included in a prospective study. Eight patients had classic, well-defined neovascularisations, 32 patients had occult lesions. Complete ophthalmic investigations included visual acuity contrast sensitivity as well as fluorescein and indocyanine green angiographic examinations prior to treatment and 1, 3, 6, and 12 months after radiotherapy. External beam radiotherapy (8-MV photons) was delivered with a total dose of 14.4 Gy in 8 fractions of 1.8 Gy per day (Figures 1 and 2). The field size averaged 5.5 x 4.5 cm. RESULTS: No treatment related morbidity during or after treatment was obtained. After 6 months follow-up the visual acuity was improved in 2 (5%) patients and maintained at pretreatment level in 17 (42%) patients. However, 12 months post treatment a stable situation was found in 6 (15%) patients and a decrease in visual acuity in 34 (85%) patients (Table 1). The central visual fields deteriorated significantly from 16.5 decibel (dB) to 12.4 dB. The enlargement of exudates and neovascular membranes increased 5- to 7-fold. At 12 months after treatment, 3 (7.5%) patients stated that they had improved vision subjectively, 12 (30%) patients had no change and 25 (62.5%) patients suffered from subjective decrease in visual acuity. CONCLUSIONS: Using a total dose of 14.4 Gy/1.8 Gy no difference concerning visual acuity and exudative changes in comparison to the natural history on age-related macular degeneration was obtained after 12 months. However, the results of multicenter studies are to be awaited.