Liver metastases: detection by phase-contrast MR imaging

Forty patients with biopsy-proved metastatic liver cancers were studied by magnetic resonance (MR) imaging using one or more conventional (in-phase) pulse sequences and a corresponding phase-contrast (opposed-phase) pulse sequence. Pulse-sequence performance was quantitated by measuring signal-difference-to-noise (SD/N) ratios between cancerous tissue and liver. The SD/N performance of T2-weighted spin-echo (SE) pulse sequences improved when used with the phase-contrast technique. SE 2,000/30 opposed-phase images showed improved (P less than .001) SD/N in 72% of patients over in-phase images. The SD/N of T1-weighted SE or inversion recovery pulse sequences deteriorated when used with the phase-contrast technique. Changes in measured SD/N correlated well with image appearance and actual lesion detectability in individual cases. Phase-contrast imaging should be employed routinely when T2-weighted SE pulse sequences are relied on to detect liver cancer.     

Sector retinitis pigmentosa.

BACKGROUND: Retinitis pigmentosa (RP) is one of the most common hereditary retinal dystrophies and causes of visual impairment affecting all age groups. The reported incidence varies, but is considered to be between 1 in 3,000 to 1 in 7,000. Sector retinitis pigmentosa is an atypical form of RP that is characterized by regionalized areas of bone spicule pigmentation, usually in the inferior quadrants of the retina. CASE REPORT: A 57-year-old Hispanic man with a history of previously diagnosed retinitis pigmentosa came to the clinic with a longstanding symptom of decreased vision at night. Bone spicule pigmentation was found in the nasal and inferior quadrants in each eye. He demonstrated superior and temporal visual-field loss corresponding to the areas of the affected retina. Clinical measurements of visual-field loss, best-corrected visual acuity, and ophthalmoscopic appearance have remained stable during the five years the patient has been followed. DISCUSSION: Sector retinitis pigmentosa is an atypical form of RP that is characterized by bilateral pigmentary retinopathy, usually isolated to the inferior quadrants. The remainder of the retina appears clinically normal, although studies have found functional abnormalities in these areas as well. Sector RP is generally considered a stationary to slowly progressive disease, with subnormal electro-retinogram findings and visual-field defects corresponding to the involved retinal sectors. CONCLUSION: Management of RP is very difficult because there are no proven methods of treatment. Studies have shown 15,000 IU of vitamin A palmitate per day may slow the progression, though this result is controversial. Low vision rehabilitation, long wavelength pass filters, and pedigree counseling remain the mainstay of management.     

Osteosarcoma: use of MR imaging and MR spectroscopy in clinical decision making

Magnetic resonance (MR) imaging was performed on 14 patients with histologically proved osteosarcoma (mean age, 14.4 years). There was excellent correlation of intramedullary tumor extent as determined with MR imaging and pathologic examination (r = 99%). This was facilitated by the presence of a chemical shift artifact at the tumor-marrow interface on the T1-weighted images. The correlation between CT and pathologic findings was not as good (r = 84%). In a single patient, however, a 10-cm length of sclerotic bone was incorrectly interpreted as being tumor. If this case is excluded, the correlation between CT and pathologic findings improves significantly (r = 96%). T2-weighted images were optimal in demonstrating soft-tissue bulk and breach of the epiphysis or cortex. Vascular involvement was also readily defined. The T2 value of the tumor soft-tissue component decreased in patients who were deemed to have responded well to therapy. Two patients with very high T2 values after chemotherapy developed wide-spread metastatic disease and died. Phosphorus-31 MR spectroscopy of five patients with osteosarcoma showed elevated levels of phosphomonoesters (PMEs), inorganic phosphate (Pi), and phosphodiesters (PDEs). PME and PDE peak areas decreased in three patients after chemotherapy, while Pi peak areas increased.     

Preoperative evaluation of abdominal aortic aneurysms by computed tomography

A prospective, preoperative study was conducted of 50 electively repaired abdominal aortic aneurysms comparing the CT and angiographic findings with those described at surgery. CT demonstrated all 50 aneurysms and correctly identified their proximal extent in relation to the takeoff of the renal arteries in 47 patients (94%), while angiography detected 48 aneurysms (96%) and their correct relation to the renal arteries in all (100%). CT correctly identified 40 (98%) of 41 patients with two renal arteries, but only two (29%) of seven with three and none of two patients with four arteries. Common iliac artery involvement or lack thereof was accurately predicted in 42 (84%) of the 50 patients and internal iliac artery aneurysms found in one (33%) of three patients. It was concluded that CT is not sufficiently accurate for documenting location and patency of the renal arteries to allow its routine substitution for angiography in patients undergoing preoperative assessment of abdominal aortic aneurysms.     

MR imaging of splenic metastases: ferrite-enhanced detection in rats

Detection of intrasplenic neoplasms using sonography, CT, and scintigraphy is limited by poor inherent tumor-spleen contrast relative to image noise. Despite the wide range of contrast parameters available for MR imaging, similar limitations have been found with this technique. Magnetopharmaceuticals have the ability to enhance tumor-spleen contrast and improve lesion detectability. In this study, a rodent model of cancer metastasized to the spleen was used to evaluate the potential of superparamagnetic ferrite particles as a tissue-specific reticuloendothelial contrast agent. Other studies have shown ferrite to have little or no toxicity. Without contrast material, metastatic adenocarcinoma of the spleen could not be distinguished from normal splenic parenchyma on in vivo MR images. At a dose of 50 mumol Fe/kg, the T2 relaxation time of spleen decreased by 77%, while tumor T2 was essentially unchanged (p less than .005). Intrasplenic tumors 4-6 mm in size became readily detectable on in vivo MR images after the administration of ferrite particles. Lesion conspicuity, quantitated by the tumor-spleen contrast-to-noise ratio, showed a 43-fold increase. Ferrite particles show great promise as a contrast agent to enhance the detection of focal splenic lesions.     

Superparamagnetic iron oxide-enhanced MR imaging: pulse sequence optimization for detection of liver cancer

The effects of magnetic resonance (MR) pulse sequences and timing parameters on tumor-liver contrast were studied in an animal model of metastatic liver cancer. Six spin-echo (SE), three inversion-recovery (IR), and four gradient-echo (GRE) sequences were evaluated at 0.6 T before and after injection of super-paramagnetic iron oxide. GRE techniques, irrespective of echo time and flip angle, showed the greatest change in signal intensity (enhancement) of the liver after administration of iron oxide. Single-acquisition GRE sequences (16 seconds) matched the contrast-to-noise ratio (C/N) performance of the most effective 6.4-minute SE sequences. Multiexcitation GRE sequences showed tumor-liver C/Ns per unit time that were significantly (P less than .05) higher than those achieved with SE and IR sequences. GRE sequences, which recruit intravoxel dephasing as an additional source of transverse relaxation enhancement (T2*), show a higher C/N per unit time and in this respect seem superior to SE and IR sequences for MR imaging with superparamagnetic iron oxide.     

中药癌痛克对人肝癌细胞HepG2增殖、凋亡及Rb基因表达的影响

目的:通过观察不同浓度癌痛克对肝癌细胞株HepG2增殖及凋亡的作用,以及在相应状态下细胞内Rb基因表达量的改变,探讨中药癌痛克抗肝癌的可能作用机制。方法:实验于2005-09/2006-03在广州医学院中心实验室完成。取对数生长期的HepG2细胞,使细胞静止于G0/G1期。随机分为癌痛克2,10,50mg/L组和对照组,癌痛克2,10,50mg/L组分别加入对应浓度癌痛克(购自河南省肿瘤研究所,由金蝎、土元、九香虫、大黄、人参、灵芝、黄芪等纯中药组成的粉状制剂,功能:消癌肿、消癌痛、消积水、升白排毒),对照组不加药物,每组设4个复孔。MTT法检测各组细胞24,48,72h增殖率,细胞增殖率=[(A570癌痛克组-A570对照组)/A570对照组]×100%;以流式细胞术检测各组细胞24,48,72h凋亡率;RT-PCR方法检测各组细胞24,48,72h细胞内Rb基因mRNA表达量。结果:①2～50mg/L癌痛克具有明显的增殖抑制作用,癌痛克2,10,50mg/L组在24,48,72h与对照组比较,差异有显著性意义(P<0.05);3组各时点两两之间比较差异有显著性意义(P<0.05);同组各时点之间比较差异有显著性意义(P<0.05)。②2～50mg/L癌痛克组可诱导HepG2细胞凋亡,相同作用时间癌痛克2,10,50mg/L组与对照组比较差异有显著性意义(P<0.001);同一时点各组比较差异有显著性意义(P<0.05);同组不同作用时间点比较差异有显著性意义(P<0.001)。③2～50mg/L癌痛克可上调Rb基因的表达,各浓度组在各时点与对照组比较,差异均有显著性意义(P<0.05);24,48,72h癌痛克2,10,50mg/L组之间比较差异无显著性意义(P>0.05);3组各时点比较差异有显著性意义(P<0.05)。结论:中药癌痛克可通过抑制HepG2细胞增殖或诱导其凋亡,而发挥抗肝癌作用;且其诱导细胞凋亡的机制之一可能为通过增加Rb基因的表达而实现。     

High-frequency vibration training increases muscle power in postmenopausal women

OBJECTIVE: To test whether training on a high-frequency (28Hz) vibrating platform improves muscle power and bone characteristics in postmenopausal women. DESIGN: Randomized controlled trial with 6-month follow-up. SETTING: Outpatient clinic in a general hospital in Italy. PARTICIPANTS: Twenty-nine postmenopausal women (intervention group, n=14; matched controls, n=15). INTERVENTION: Participants stood on a ground-based oscillating platform for three 2-minute sessions for a total of 6 minutes per training session, twice weekly for 6 months. The controls did not receive any training. Both groups were evaluated at baseline and after 6 months. MAIN OUTCOME MEASURES: Muscle power, calculated from ground reaction forces produced by landing after jumping as high as possible on a forceplate, cortical bone density, and biomarkers of bone turnover. RESULTS: Over 6 months, muscle power improved by about 5% in women who received the intervention, and it remained unchanged in controls (P=.004). Muscle force remained stable in both the intervention and control groups. No significant changes were observed in bone characteristics. CONCLUSION: Reflex muscular contractions induced by vibration training improve muscle power in postmenopausal women.