Uday K. Mehta

Magnetic resonance imaging of the pancreas at 3.0 tesla: qualitative and quantitative comparison with 1.5 tesla.

Objectives:We sought to perform a preliminary comparison of signal-to-noise ratio (SNR) and image quality for magnetic resonance imaging (MRI) of the pancreas at 1.5 and 3 T. Materials and Methods:Two imaging cohorts were studied using a T2-weighted, single-shot fast spin-echo pulse sequence and a T1-weighted, fat-suppressed 3D gradient-echo pulse sequence. In the first cohort, 4 subjects were imaged using identical imaging parameters before and after contrast administration at 1.5 and 3.0 T. The SNR was quantified for the pancreas as well as for the liver, spleen, and muscle. In a second cohort of 12 subjects in whom the receiver bandwidth was adjusted for field strength, SNR measurements and qualitative rankings of image quality were performed. Results:In the study cohort using identical imaging parameters at both magnetic field strengths, the mean (SD) ratios of SNR at 3.0 to 1.5 T of the single-shot fast spin-echo images for the pancreas, liver, spleen, and muscle were 1.63 (0.39), 1.82 (0.39), 1.45 (0.18), 2.01 (0.16), respectively. For the precontrast fat-suppressed 3D gradient-echo sequence, the corresponding ratios were 1.28 (0.29), 1.26 (0.30), 1.16 (0.27), and 1.76 (0.45), respectively; for the arterial phase, the corresponding ratios were 2.02 (0.28), 1.60 (0.42), 1.47 (0.26), and 1.94 (0.32), respectively; and for the delayed postcontrast phase, the corresponding ratios were 1.63 (0.51), 2.01 (0.25), 1.66 (0.06), and 2.31 (0.47), respectively. The SNR benefit of 3.0 T was significantly greater on contrast-enhanced as compared with noncontrast T1-weighted 3D gradient-echo images. In the second study cohort, SNR was superior at 3.0 T, although the use of a reduced readout bandwidth at 1.5 T substantially diminished the advantage of the higher field system. With qualitative comparison of images obtained at the 2 magnetic field strengths, the fat-suppressed 3D gradient-echo images obtained at 3.0 T were preferred, whereas the single shot fast spin-echo images obtained at 1.5 T were preferred because of better signal homogeneity. Conclusions:Our results in a small cohort of volunteers and patients demonstrate a marked improvement in SNR at 3.0 T compared with 1.5 T (by a factor of 2 in some cases) when identical imaging parameters were used. The SNR advantage at 3.0 T is diminished but persists when the receiver bandwidth is adjusted for magnetic field strength. The results suggest that 3.0 T may offer promise for improved body MRI, although further technical development to optimize SNR and improve signal homogeneity will be needed before its full potential can be achieved.

Diagnosis and staging of small bowel tumours

Small bowel neoplasms comprise only 1% of gastrointestinal neoplasms. Despite their rarity, it is important to diagnose small bowel tumours early to maximize patient survival.

Metastatic Basal Cell Carcinoma: Complete Response to Chemotherapy and Associated Pure Red Cell Aplasia

Basal cell carcinoma (BCC) is usually a benign and indolent cancer cured in greater than 95 percent of cases. Nevertheless, it can be locally destructive or occasionally metastasize to distant organs. We report a case of BCC metastatic to the lungs, occurring 17 years after the primary BCC was noticed, that responded to carboplatin and paclitaxel on 3 occasions. The patient also developed pure red cell aplasia (PRCA). Work-up did not reveal underlying thymoma or infectious, rheumatologic, or lymphoproliferative disorders. Parvovirus serologies were negative, and antibodies against erythropoetin were not detected. There was no history of exposure to drugs associated with PRCA. Bone marrow biopsy on 2 different occasions did not show evidence of myelodysplasia. PRCA may represent an unusual paraneoplastic syndrome associated with BCC as reported with other carcinomas. This is the first report of PRCA associated with metastatic BCC or the drugs carboplatin and paclitaxel, which were used to treat it. The literature on chemotherapy for metastatic BCC is reviewed.

Imaging in Intestinal Ischemic Disorders

Intestinal ischemia and infarction are a heterogeneous group of diseases that have as their unifying theme hypoxia of the small bowel and/or colon. The incidence of bowel ischemia is increasing for a number of reasons: the aging of the population, the ability of intensive care units to salvage critically ill patients, and heightened clinical awareness of these disorders. Improvements in diagnostic imaging techniques have contributed greatly to the earlier diagnosis of intestinal ischemia, which can have a positive influence on patient outcomes. In this review, advances in multidetector computerized tomography, magnetic resonance, and ultrasound in the detection of intestinal ischemia are highlighted and placed in the context of expeditious patient management.

That liver lesion on MDCT in the oncology patient: is it important?

Abstract Multidetector-row computed tomography (MDCT) has become the primary imaging test for the staging and follow-up of most malignancies that originate outside of the central nervous system. Technical advances in this imaging technique have led to significant improvement in the detection of metastatic disease to the liver. An unintended by-product of this improving diagnostic acumen is the discovery of incidental hepatic lesions in oncology patients that in the past remained undetected. These ubiquitous, incidentally identified hepatic lesions have created a management dilemma for both clinicians and radiologists: are these lesions benign or do they represent metastases? Naturally, the answer to this question has profound prognostic and therapeutic implications. In this review, guidelines concerning the diagnosis and management of some of the more common hepatic incidental lesions detected in patients with extrahepatic malignancies are presented.

Pathways of abdominal tumour spread: the role of the subperitoneal space

Abstract The subperitoneal space is a large, unifying, anatomically continuous potential space that connects the peritoneal cavity with the retroperitoneum. This space is formed by the subserosal areolar tissue that lines the inner surfaces of the peritoneum and the musculature of the abdomen and pelvis. It contains the branches of the vascular, lymphatic, and nervous systems that supply the viscera. The subperitoneal space extends into the peritoneal cavity and is invested between the layers of the mesenteries and ligaments that support and interconnect the abdominal and pelvic organs. As such, it provides one large continuous space in which infectious, neoplastic, inflammatory, and hemorrhagic disease may spread in many directions.

The incidental cystic pancreas mass: a practical approach.

Abstract Technical advances in cross-sectional imaging have led to the discovery of incidental cystic pancreatic lesions in the oncology and non-oncology population that in the past remained undetected. These lesions have created a diagnostic and management dilemma for both clinicians and radiologists: should these lesions be ignored, watched, aspirated, or removed? In this review, recommendations concerning the assessment of the more common pancreatic cystic incidental lesions are presented.

Upper gastrointestinal tumours: diagnosis and staging

Upper GI tumours have a dismal prognosis. Only early diagnosis and accurate staging can optimize patient management.