Added value of diffusion‐weighted imaging in the MRI assessment of perilesional tumor recurrence after chemoembolization of hepatocellular carcinomas

Purpose

To investigate the additional value of diffusion‐weighted imaging (DWI) in the MRI assessment of perilesionally recurrent hepatocellular carcinomas (HCCs) after transcatheter arterial chemoembolization (TACE).

Materials and Methods

For gadopentetate dimeglumine‐enhanced multiphasic dynamic images with precontrast T1‐ and T2‐weighted images of 23 patients treated with TACE, two radiologists independently sorted the confidence levels for the presence of a viable tumor in the vicinity of the treated lesions into five grades. In another session, images from DWI (b factor = 50, 400, and 800 s/mm²) were added to the previously reviewed images and the same radiologists sorted the confidence levels.

Results

A total of 26 lesions (0.7–3.5 cm) from 16 patients were confirmed to be perilesional recurrences of HCC. The area under the receiver operating characteristic curve (A_z) for the second interpretation session (0.826) was not significantly different (P = 0.299) from that of the first session (0.859). The overall sensitivity was increased from 85% to 92%, but the specificity decreased from 65% to 50% after adding DWI.

Conclusion

The addition of DWI has the potential to improve sensitivity, but not the overall diagnostic accuracy, in the assessment of perilesional recurrence of HCCs after chemoembolization. J. Magn. Reson. Imaging 2009;30:153–160. © 2009 Wiley‐Liss, Inc.     

Quantitative Analysis of the Effect of Iterative Reconstruction Using a Phantom: Determining the Appropriate Blending Percentage

Purpose

To investigate the optimal blending percentage of adaptive statistical iterative reconstruction (ASIR) in a reduced radiation dose while preserving a degree of image quality and texture that is similar to that of standard-dose computed tomography (CT).

Materials and Methods

The CT performance phantom was scanned with standard and dose reduction protocols including reduced mAs or kVp. Image quality parameters including noise, spatial, and low-contrast resolution, as well as image texture, were quantitatively evaluated after applying various blending percentages of ASIR. The optimal blending percentage of ASIR that preserved image quality and texture compared to standard dose CT was investigated in each radiation dose reduction protocol.

Results

As the percentage of ASIR increased, noise and spatial-resolution decreased, whereas low-contrast resolution increased. In the texture analysis, an increasing percentage of ASIR resulted in an increase of angular second moment, inverse difference moment, and correlation and in a decrease of contrast and entropy. The 20% and 40% dose reduction protocols with 20% and 40% ASIR blending, respectively, resulted in an optimal quality of images with preservation of the image texture.

Conclusion

Blending the 40% ASIR to the 40% reduced tube-current product can maximize radiation dose reduction and preserve adequate image quality and texture.     

Accuracy of gadoxetic acid-enhanced magnetic resonance imaging for the diagnosis of sinusoidal obstruction syndrome in patients with chemotherapy-treated colorectal liver metastases

Objective  

To assess whether reticular hypointensity on hepatobiliary phase images of gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) is a diagnostic finding of sinusoidal obstruction syndrome (SOS) in patients with hepatic metastases who have undergone chemotherapy.     

Effect of Glucagon-like Peptide-2 (GLP-2) on Diurnal SGLT1 Expression

Glucagon-like peptide 2 (GLP-2) is a 33-amino acid gut peptide that leads to villus hyperplasia and altered gene expression. We examined the effect of chronically administered GLP-2 on diurnal gene expression rhythms using the Na+/glucose cotransporter 1 (SGLT1) as the index. Animals were treated with [Gly2]GLP-2 (twice daily; 1microg/g body weight) or vehicle (control) for 10 days. Rats were killed at either 3 hr or 9 hr after light onset (ZT3 and ZT9, respectively), an interval during which SGLT1 expression exhibits a robust induction. SGLT1 mRNA expression was assessed by Northern blotting and in situ hybridization. SGLT1 protein was examined by immunofluorescence and Western blotting. Tissues from GLP-2-treated rats had increased villus height, crypt depth, and proliferation index (P < 0.05). GLP-2 administration did not alter the diurnal increase in mRNA levels of SGLT1, GLUT2, or GLUT5. However, in GLP-2-treated rats, the SGLT1 protein amount increased at both ZT3 and ZT9. Moreover, SGLT1 was preferentially localized to the apical membranes in this group. GLP-2 does not adversely affect the diurnal expression rhythm of SGLT1 and appears to increase membrane expression of the protein. These biological actions of GLP-2 may contribute to its therapeutic value in intestinal diseases.     

Transvaginal cholecystectomy without laparoscopic support using prototype flexible endoscopic instruments in a porcine model

Background

Transvaginal cholecystectomy with laparoscopic assistance has been performed safely in humans. The next goal was to develop a natural orifice transluminal endoscopic surgery (NOTES) technique to perform cholecystectomy without laparoscopic instruments using one flexible endoscope and flexible accessories. The aim of the study was to test the feasibility of the procedure in a survival porcine model.

Methods

Cholecystectomies were attempted in five 88–130-lb. pigs with a planned 2-week survival. Prototype flexible instruments (NOTES Toolbox, Ethicon Endo-Surgery, Inc.) were used to aid in access, dissection, and removal of the gallbladder via the transvaginal route.

Results

Cholecystectomy could be completed without abdominal incision using prototype instruments in four out of five pigs. The cystic duct could be exposed with a flexible hook knife and clips applied. The steerable trocar improved stability and the precision of the dissection. The critical view was established in all five pigs. Dissection of the gallbladder off the liver bed was imprecise resulting in gallbladder perforation in all pigs and liver hemorrhage in two. At necropsy, all clips on the cystic duct were secure and no bile leak, bowel injury, or adhesions were present.

Conclusions

NOTES cholecystectomy without laparoscopic support is feasible but challenging using prototype flexible endoscopic devices. A prototype clip applier was effective in controlling the cystic duct. Further improvements in instrument design to ensure precision and safety are needed before flexible devices should be used for pure NOTES procedures in humans.     

Incidence of hypohydration when consuming carbohydrate-electrolyte solutions during field training

Carbohydrate-electrolyte solutions (CE1, CE2) were evaluated for their ability to reduce the incidence of hypohydration during field training in hot weather (max Tamb = 88 degrees-100 degrees F). Hydration status was monitored twice daily in Army reservists who consumed ad libitum CE1, or CE2, or water, or a flavored water placebo. The water group had the highest percentage incidence of urine specific gravity greater than or equal to 1.030 (22%), whereas CE2 and flavored water placebo groups had the lowest (6% and 8%, respectively). Average total fluid intake was greatest in CE2 and lowest in CE1. CE2 and flavored water placebo were more effective than CE1 and water in reducing the overall incidence of hypohydration during this field exercise.     

A case of giant congenital nevocytic nevus with neurotization and onset of vitiligo

The authors report the case of a 21-year-old woman with a giant congenital nevocytic nevus (GCNN) who developed vitiligo at the age of 16 years on skin areas remote from the GCNN. This is the first reported case of GCNN developing neurotization combined with vitiliginous changes within the GCNN lesion. Treatment with PUVA achieved repigmentation of the vitiligo lesions, except for the hypochromic areas within the area of the nevus that were shielded from UVA radiation.