Assessment of clinical renal preservation by phosphorus-31 magnetic resonance spectroscopy

To evaluate the role of magnetic resonance spectroscopy (MRS) and to develop surface coils for assessing cadaveric renal viability during hypothermic storage, we used the monophosphate/inorganic phosphate ratio (MP/Pi) to monitor phosphorous metabolites in intact kidneys during various renal preservation maneuvers. Eighteen canine kidneys and 16 cadaveric kidneys were studied as follows: Group 1 (N = 4) in situ kidneys were monitored by implanted MRS coils; Group 1 (N = 4) ex vivo kidneys were immediately attached to vascular cannulas and monitored by MRS surface coils during normothermic perfusion; Group 3 (N = 4) kidneys were removed, cold-flushed and, after 24 hours of 4C storage, monitored by MRS surface coils before and during four hours of reperfusion via vascular cannulas; Group 4 (N = 6) kidneys were removed, cold-flushed and monitored by surface coils during cold storage up to 72 hours. In addition, 16 cadaveric kidneys were studied while in sterile cold-storage containers. Postoperative renal function was followed in recipient patients. The MP/Pi ratios in Group 1 kidneys correlated with the ability to regenerate adenosine triphosphate (ATP). Groups 2 and 3 showed similar regeneration of ATP and MP/Pi after postischemic reperfusion, and the signal-to-noise ratios of the surface coils were better than those in the implanted coils in Group 1. Surface-coil monitoring in Group 4 kidneys showed predictable decay rates of MP/Pi during one to 72 hours of cold storage; in contrast, simultaneous cortical medullary microcirculation studies with 99mTc-macroaggregated albumin were inconclusive. Human cadaveric kidneys with high MP levels were associated with excellent renal function after transplantation, while those with low MP (less than or equal to 0.50) were associated with nonviability. We conclude that MRS is a practical and safe diagnostic modality for clinical transplantation.     

Complex fetal disorders: effect of MR imaging on management--preliminary clinical experience

PURPOSE: To determine the effect of magnetic resonance (MR) imaging findings on management of complex fetal disorders. MATERIALS AND METHODS: MR imaging of the fetus was performed in 25 consecutive pregnant patients referred because of possible complex fetal disorders suspected on the basis of ultrasonographic (US) findings. Spoiled gradient-echo and single-shot rapid acquisition with relaxation enhancement MR imaging were performed in multiple planes anatomic to the fetus during maternal breath holding. RESULTS: In the fetuses in 24 of 25 women, MR studies were technically satisfactory. MR imaging directly influenced fetal care in four (17%) of 24 cases by demonstrating congenital high airway obstruction syndrome, congenital hemochromatosis, unilateral cerebellar deficiency in association with congenital diaphragmatic hernia, and severe facial disfigurement due to a giant anterior neck mass. In eight (33%) cases, MR imaging provided supplementary findings, but did not affect fetal care. In 12 (50%) cases, MR imaging results confirmed US findings. CONCLUSION: In cases of complex fetal disorders, MR imaging results can be used to supplement or confirm US findings and may directly affect management.     

Magnetic resonance imaging of renal calculi: an in vitro study

Extracorporeal shock wave lithotripsy (ESWL) has been established as a standard method of urinary stone treatment. Poor fragmentation with an increased rate of complications has been noticed with certain calculi types (calcium oxalate monohydrate and cystine). In devising appropriate pre-operative strategies, it would be useful to know the calculi composition. We have investigated the in vitro utility of using magnetic resonance imaging (MRI) in analyzing urinary calculi. Our in vitro analysis found no difference in signal characteristics between calculi of varying composition. The absence of signal can be understood from a molecular basis. We conclude that MRI will not offer any assistance in characterizing the composition of urinary calculi.     

Advances in oncologic imaging

Imaging has become a pivotal component throughout a patient's encounter with cancer, from initial disease detection and characterization through treatment response assessment and posttreatment follow‐up. Recent progress in imaging technology has presented new opportunities for improving clinical care. This article provides updates on the latest approaches to imaging of 5 common cancers: breast, lung, prostate, and colorectal cancers, and lymphoma. CA Cancer J Clin 2012. © 2012 American Cancer Society.     

Spermatic cord torsion: diagnostic limitations

To distinguish spermatic cord torsion from other intrascrotal pathology, scrotal ultrasound and radionuclide scanning have been highly recommended on the basis of both clinical and experimental studies. We review the data from six patients in whom ultrasound or nuclear medicine examination was misleading. We emphasize that history, physical examination, and urinalysis remain the cornerstones of the diagnosis of spermatic cord torsion. Scrotal ultrasound and nuclear medicine scans are useful adjuncts and are reassuring when in agreement with the clinical picture. However, they are not 100% sensitive or specific, and a negative study should not prevent emergency operative exploration of a clinically suspicious lesion.     

Prostate volumes defined by magnetic resonance imaging and computerized tomographic scans for three-dimensional conformal radiotherapy

To compare the prostate volumes defined on magnetic resonance imaging (MRI), and noncontrast computerized tomographic (CT) scans used for three-dimensional (3D) treatment planning.

: Ten patients simulated for treatment using immobilization and a retrograde urethrogram. 3D images were used to compare prostate volumes defined by MRI (4–6 mm thick slices) and CT images (5 mm thick slices). Prostate volumes were calculated in cm³ using the Scanditronix 3D planning system. MRI/CT images were merged using bony anatomy to define the regions of discrepancy om prostate volumes.

: The mean prostate volume was 32% larger (range −5–63%) when defined by noncontrast CT compared to MRI. The areas of nonagreement tended to occur in four distinct regions of discrepancy: (a) the posterior portion of the prostate, (b) the posterior-inferior-apical portion of the prostate, (c) the apex due to diasgreement between a urothrogram based definition and the location defined by MRL, (d) regions corresponding to the neurovascular bundle.

: There is a tendency to overestimate the prostate volume by noncontrast CT compared to MRI. Awareness of this tendency should allow us to be to more accurately define the prostate during 3-D treatment planning.     

The prostate: MR imaging and spectroscopy. Present and future

The applications of combined MR imaging and MR spectroscopic imaging of prostate cancer have expanded significantly over the past 10 years and have reached the point of clinical trial results to test robustness and clinical significance. MR spectroscopic imaging extends the diagnostic evaluation of prostate cancer beyond the morphologic information provided by MR imaging throughout the detection of cellular metabolites. The combined metabolic and anatomic information provided by MR imaging and MR spectroscopic imaging has allowed a more accurate assessment of the presence, location, extent, and aggressiveness of prostate cancer both before and after treatment. This information has already demonstrated the ability to improve therapeutic planning for individual prostate cancer patients and shows great promise in the assessment of therapeutic response and the evaluation of new treatment regimes.