Detection of colorectal polyps by computed tomographic colography: feasibility of a novel technique

BACKGROUND & AIMS

Computed tomographic colography (CTC) represents a novel technique for colorectal polyp detection. A prospective study was undertaken to determine the optimal CTC scanning parameters based on an artificial colon model and to assess the feasibility of CTC to detect clinically significant colorectal polyps.

METHODS

A colon model was scanned by helical computed tomography at multiple parameters. Reformatted two-dimensional and three-dimensional images were then graded for polyp detection and image quality. Subsequently, 10 patients with known colon polyps underwent CTC immediately before colonoscopy. The number of polyps detected by two radiologists using CTC were compared with colonoscopy results that served as the gold standard.

RESULTS

The optimal scanning parameters in the colon model were 5-mm collimation, 5 mm/s table speed, and 1-mm reconstruction interval. Ten patients had 30 polyps (range, 0.2-2.0 cm) by colonscopy, and all polyps > or = 0.5 cm were adenomas. Polyp detection by CTC for both observers was 100% (5 of 5) > or = 1 cm, 71% (5 of 7) between 0.5 and 0.9 cm, and 11%-28% (2-5 of 18) < 0.5 cm.

CONCLUSIONS

Based on this small, unblinded pilot study, CTC is feasible for colorectal polyp detection > or = 0.5 cm in diameter.

Abdominal phase-contrast MR angiography: breath-hold versus non-breath-hold techniques

Breath-hold magnetic resonance (MR) imaging is now replacing many non-breath-hold pulse sequences in the upper abdomen because of faster imaging times and improved image quality. The authors compared non-breath-hold cine phase-contrast (PC) and breath-hold 2D phase-contrast (2DPC) magnetic resonance (MR) angiograms of the main portal vein (MPV) and superior mesenteric artery (SMA) in 12 volunteers. All angiograms were graded in overall image quality, vessel conspicuity, and signal-to-noise ratios (SNR). In the MPV MR angiograms, the breath-hold 2DPC sequence produced better images than the non-breath-hold cine PC sequence as graded by overall image quality (P = .016) and SNR (P = .004). Conversely, in the SMA MR angiograms, the non-breath-hold cine PC sequence produced better images than the breath-hold sequence in terms of overall image quality (P = .008) and SNR (P = .008). By reducing the most significant cause of image artifacts, (ie, using a breath-hold 2DPC sequence to decrease respiratory misregistration of the MPV, and using a cardiac-gated cine PC sequence to minimize pulsatile artifacts of the SMA), one can clearly optimize the quality of MR angiography.

Single-pass CT of hepatic tumors: value of globular enhancement in distinguishing hemangiomas from hypervascular metastases

OBJECTIVE

The purpose of this study was to evaluate the sensitivity and specificity of globular enhancement for differentiating hepatic hemangiomas from hypervascular metastases on single-pass, contrast-enhanced CT scans. Globular enhancement was defined as enhancing nodules less than 1 cm seen within a lesion.

MATERIALS AND METHODS

Fifty CT examinations were retrospectively evaluated in a blinded fashion by two independent reviewers. The CT studies were done with nonhelical technique after the IV injection of 150 ml of contrast material. The series included 25 patients with histologically proven hypervascular hepatic metastases (carcinoid, islet cell carcinoma, and leiomyosarcoma) and 25 patients with clinically proven hepatic hemangiomas. Patients with hemangiomas were clinically stable for at least 2 years after the CT studies. A single lesion was isolated from the first-pass, contrast-enhanced portion of each examination; the remainder of the examination was excluded from the review to minimize reviewer bias. Each lesion was evaluated for (1) the presence or absence of globular enhancement (defined as enhancing nodules less than 1 cm seen within a lesion), (2) the density of globular enhancement relative to that of the aorta, (3) the degree of border definition (well or poorly marginated), and (4) the presence or absence of a hypodense halo. A diagnostic impression was then recorded for each lesion.

RESULTS

Globular enhancement was 88% sensitive and 84-100% specific for differentiating hepatic hemangiomas from hypervascular metastases (p < .001). A mean of 62% of hemangiomas showed globular enhancement isodense relative to that of the aorta; none of the metastases showed globular, isodense enhancement. The majority of the metastases showed nonglobular enhancement (mean, 92%). The reviewers showed 84% agreement in the identification of (1) globular enhancement in hemangiomas, (2) lack of globular enhancement in metastases, and (3) globular enhancement in the combined set of all lesions. Neither the presence of a hypodense halo nor the degree of border definition was significant in distinguishing between the two groups of lesions. The reviewers showed 96% agreement in the categorization of metastases and 76% agreement in the categorization of hemangiomas. There was 86% agreement in the categorization of all lesions. Overall, reviewers diagnosed a mean of 89% of lesions correctly. A mean of 98% of metastases and a mean of 80% of hemangiomas were diagnosed correctly.

CONCLUSIONS

Globular enhancement is highly sensitive (88%) and specific (84-100%) for differentiating hepatic hemangiomas from hypervascular metastases on single-pass, contrast-enhanced CT scans.

Gallbladder motility, gallstones, and the surgeon

Cholecystectomy is one of the commonest surgical procedures in the Western world, with more than half a million procedures performed annually in the United States alone. In recent years, studies of gallstone pathogenesis and gallbladder disease have increasingly focused on abnormal gallbladder motility in the pathogenesis of some, if not all, gallbladder conditions. The control of gallbladder motility is complex and depends on an intricate interplay of neural and hormonal factors. An understanding of the control of gallbladder motility is crucial to the understanding of the mechanisms of gallstone formation and may help to explain the failure to cure symptoms after cholecystectomy in up to one third of patients. The purpose of this article is to outline mechanisms controlling gallbladder motility, examine recent developments in our understanding of this complex process, and relate changes in motility to common disease conditions of the gallbladder. The role of altered motility in the pathogenesis of gallstones is discussed and the effects of commonly performed surgical procedures such as truncal vagotomy and cholecystectomy on upper gut physiology are reviewed.

Gadoteridol-enhanced MR imaging of malignant hepatic tumors: effects of triple versus standard doses on lesion-liver contrast

OBJECTIVE

The purpose of this study was to compare liver signal-to-noise ratio (SNR), lesion SNR, and lesion-liver contrast-to-noise-ratio (CNR) in patients with malignant liver lesions after the administration of a standard dose (0.1 mmol/kg of body weight) or a triple dose (0.3 mmol/kg) of a gadolinium chelate (gadoteridol). We hypothesized that the higher dose would produce a higher lesion-liver CNR and therefore increase the conspicuity of hepatic lesions.

MATERIALS AND METHODS

A total of 85 patients with malignant hepatic masses (61 metastases, 22 hepatocellular carcinomas, and two lymphomas) proved by histologic or follow-up studies underwent MR imaging at 1.5 T. T1-weighted spin-echo imaging and gradient-echo imaging were done before and within 1 min after (gradient echo) as well as 5 (spin echo) and 15 (spin echo) min after the injection of 0.1 or 0.3 mmol of gadoteridol per kg, randomized before the start of the study (39 patients received the standard dose, and 46 received the triple dose). The signal intensities of the liver and lesions and the SD of background noise were measured by use of regions of interest to calculate the SNR of the liver and malignant lesions and the lesion-liver CNR.

RESULTS

The lesion-liver CNR was increased significantly at 5 and 15 min after the administration of gadoteridol. No significant differences in the liver SNR, lesion SNR, and lesion-liver CNR (after 1 min: standard dose, -5 +/- 8, and triple dose, -4 +/- 14; after 5 min: standard dose, -1 +/- 5, and triple dose, 2 +/- 8; and after 15 min: standard dose, 1 +/- 5, and triple dose, 6 +/- 20) were found between the doses at all time points.

CONCLUSION

Triple-dose gadoteridol does not improve the lesion-liver contrast of malignant hepatic lesions over that provided by the standard dose and is not warranted for liver MR imaging.

Extended lymph node dissection (D2 resection) should now be performed routinely in the curative surgical treatment of gastric carcinoma

Gastric cancer has a dismal prognosis in the Western world. In contrast, in Japan where extended lymphadenectomy is the rule in curative gastric cancer surgery, the prognosis is much better. The arguments for and against the adoption of this procedure in the West are presented. This procedure is safe in the hands of experienced surgeons and by improving locoregional control, may improve survival. However, in the absence of controlled data supporting a survival advantage, the excess morbidity and mortality of this extended procedure in the West may not be justified.

Tuberculosis of the pancreas

Tuberculosis of the pancreas is extremely rare. We report a case which demonstrates the diagnostic confusion which may arise in this condition. A 55-year-old alcoholic caucasian man presented with loss of weight and obstructive jaundice. Ultrasonography, endoscopic retrograde cholangiopancreatography and computed tomography showed a mass lesion in the head of the pancreas, diagnosed as probably malignant. He underwent a Whipple's pancreatoduodencetomy and made a good recovery. Histological examination showed typical features of tuberculosis. In the absence of other foci of active disease chemotherapy was not given. He remains well 12 months after operation.

Abdominal mass in a patient with Crohn's disease

Images

"Research" and "science" in the first half of the chiropractic century

In the first 50 years of the chiropractic profession, a variety of unorthodox meanings for the terms "research," "science" and related words were in evidence. In harmony with popular conceptions of the day, science was constructed as a relatively static body of knowledge and was thought to reflect the will of God. Research was an ill-defined activity, and acquisition of new knowledge did not involve the experimental methodology that increasingly took hold in biology and medicine in the twentieth century. Chiropractors often viewed science and research as marketing strategies. Clinical data collection, when it occurred at all, was not described in sufficient detail to permit replication. Results were enthusiastically interpreted as indisputable proof of investigators' a priori assumptions about the effectiveness of chiropractic methods. A few in the profession recognized the general lack of understanding of the scientific method and sought reform from within. However, the colleges were unwilling to introduce coursework in research methods. At the end of World War II, the broad-scope national association of chiropractors in the United States established a nonprofit foundation for the purpose of raising funds for chiropractic research and education. Research plans were poorly conceived and grandiose: the first major initiative of the Chiropractic Research Foundation involved a nationwide publicity and fund-raising campaign modeled after the March of Dimes. When these efforts failed and the possibility of establishing free-standing research centers collapsed, the Foundation sought to shift responsibility for research to the schools. The poverty-stricken chiropractic colleges lacked the research sophistication for this task. Several more decades would pass before a sustained research effort and interest in clinical experimentation would become evident in chiropractic.

Two-layer repair of the transversalis fascia is sufficient for inguinal hernia repair

The Shouldice four-layer repair is considered to be the gold standard procedure for repair of inguinal hernia with low recurrence rates around 1%. Tension-free two-layer repair of the transversalis fascia may be all that is required to avoid recurrence. We compared the early recurrence rate after two-layer repair of the transversalis fascia or the standard four-layer Shouldice technique in a randomised study of elective inguinal herniorrhaphy. In 48 patients (53 repairs) who had a two-layer transversalis fascia repair, there was one recurrence (2%) in the first 12 months after operation, though there was one more recurrence within 36 months (total 4%). In 39 patients who had a four-layer Shouldice repair (42 repairs), there was no recurrence at 12 months but at 36 months two recurrences (5%) were found. We conclude that a two-layer repair of the transversalis fascia is anatomically correct, physiologically sound and can provide equivalent results to the standard Shouldice repair for inguinal hernia.

Abdominal manifestations of sarcoidosis in CT studies

OBJECTIVE

The purpose of this study is to demonstrate the spectrum of abdominal CT findings in patients with tissue proved sarcoidosis, estimate their prevalence, and correlate abdominal findings with stage of thoracic disease.

MATERIALS AND METHODS

Between 1987 and 1993, 140 patients with tissue proved sarcoidosis underwent abdominal or chest CT at our institution. After exclusions, 49 patients remained. Abdominal CT was retrospectively reviewed and the findings arrived at by consensus. Chest radiography within 1 month of CT was available for 46 patients. Chest radiography was retrospectively reviewed and stage of thoracic disease arrived at by consensus.

RESULTS

Splenic abnormalities consisted of splenomegaly, low density lesions, and punctate calcifications. Hepatic sarcoidosis manifested as hypovascular lesions, hepatomegaly, and punctate calcifications. Lymphatic abnormalities consisted of lymphadenopathy, most commonly between 1 and 2 cm, and an increased number of normal sized lymph nodes.

CONCLUSION

Sarcoidosis produces splenic abnormalities in 53% of patients, liver abnormalities in 16%, and lymphatic findings in 43%. No correlation was demonstrated between the abdominal findings and stage of thoracic sarcoidosis.

MR imaging of the abdomen with a phased-array multicoil: prospective clinical evaluation

PURPOSE

To prospectively compare use of a phased-array multicoil and a conventional body coil in abdominal MR imaging.

MATERIALS AND METHODS

Thirteen patients (seven men, six women; mean age, 55 years) underwent imaging with a phased-array multicoil and with a conventional body coil. Four pulse sequences were used: T2-weighted spin echo (SE), magnetization-prepared gradient-recalled echo (GRE), breath-hold fast SE, and echo planar (EP).

RESULTS

Lesion detection improved the most on fast SE, multicoil-acquired images. Signal-to-noise ratio (S/N) increased 64% with fast SE (P = .0005) and EP (P < .0109) sequences. Contrast-to-noise ratio (C/N) doubled (P < .05) with T2-weighted SE sequences. Lesion conspicuity improved on multicoil-acquired images with all fast sequences (magnetization-prepared GRE, P = .015; fast SE, P = .002; EP imaging, P = .013). There was little difference in respiratory and vascular artifact. Depiction of most abdominal structures improved (P < .01).

CONCLUSION

Use of the phased-array multicoil provides better MR images of the abdomen than does use of a conventional body coil.

Caenorhabditis elegans mutants resistant to inhibitors of acetylcholinesterase

We characterized 18 genes from Caenorhabditis elegans that, when mutated, confer recessive resistance to inhibitors of acetylcholinesterase. These include previously described genes as well as newly identified genes; they encode essential as well as nonessential functions. In the absence of acetylcholinesterase inhibitors, the different mutants display a wide range of behavioral deficits, from mild uncoordination to almost complete paralysis. Measurements of acetylcholine levels in these mutants suggest that some of the genes are involved in presynaptic functions.

Management of ductal carcinoma in situ of the breast

The advent of mammographic breast screening has increased the detection of ductal carcinoma in situ (DCIS), which now accounts for 15-20% of all breast cancer. While symptomatic DCIS has been treated satisfactorily by mastectomy, this may be an overtreatment of smaller screen-detected lesions. Although local excision, with or without radiotherapy, is associated with a significant risk of local recurrence of DCIS or invasive cancer, salvage surgery is usually successful. The long-term breast-specific mortality rate of treatment by mastectomy and local excision are similar. Whereas mastectomy is still appropriate for women with lesions > 30 mm in diameter or centrally placed and for those women who demand the best possible disease-free survival, local surgery should otherwise be considered.

Fibrolamellar hepatocellular carcinoma: stage at presentation and results of aggressive surgical management

OBJECTIVE

The purpose of this study was to report the stage of fibrolamellar carcinoma at presentation and the imaging findings of postoperative recurrent tumor in an aggressively managed population and to assess the implications of those findings relative to the patients' management.

MATERIALS AND METHODS

Imaging studies in 10 patients with pathologically proved fibrolamellar carcinoma were reviewed. Preoperative studies included CT (n = 10), sonography (n = 8), and MR imaging (n = 2). Postoperative studies included CT (n = 9), sonography (n = 4), and MR imaging (n = 1). Imaging findings were correlated with clinical and surgical follow-up data. Patients were followed up for 2-75 months (median, 26 months).

RESULTS

At presentation, seven (70%) of 10 patients had metastatic lymphadenopathy. Seven patients (70%), including four with lymph node metastasis, had tumor resections with intent to cure. Postoperative imaging studies revealed recurrent tumor in all seven of these patients, including six patients (86%) who had intrahepatic recurrence with or without lymph node metastasis after 6-18 months, and one patient (14%) who had distant metastases 66 months postoperatively. Recurrent lesions were subsequently resected in three (43%) of seven patients, who were disease-free at a mean of 8 months after their second resection. Five patients died after 9 months mean survival, and two patients were alive with residual tumor after 3 months mean follow-up.

CONCLUSION

Fibrolamellar carcinomas are often of advanced stage at diagnosis. Recurrence after resection with intent to cure is common. Early and frequent follow-up imaging is necessary for optimizing surgical management in patients with fibrolamellar carcinoma.

A large necrotic defect secondary to a cutaneous sinus tract of odontogenic origin: a case report

This article reviews the case of a patient with a periapical dental abscess that drained inferior and posterior to the angle of the jaw and created a large purulent cutaneous defect. Both the diagnosis and treatment issues are discussed.

Upper abdominal phase-contrast MR angiography: comparison of cine and non-cine techniques

PURPOSE

To evaluate image quality, vessel conspicuity, and signal-to-noise ratio (S/N) of four two-dimensional magnetic resonance (MR) phase-contrast techniques: cine phase-contrast with respiratory compensation (CPC-R), cine phase-contrast without respiratory compensation (CPC), phase-contrast with two signals acquired (PC-2), and phase-contrast with eight signals acquired (PC-8).

MATERIALS AND METHODS

MR angiographic images of the portal vein were obtained in 14 patients.

RESULTS

Overall image quality was rated excellent in 10 of 14 patients (CPC-R), in one of 14 patients (CPC), in none of 14 patients (PC-2), and in one of 14 patients (PC-8). Views of 10 upper abdominal vessels were evaluated with each technique. The mean (+/- standard deviation) number of well-imaged vessels was 6 +/- 2 (CPC-R), 3 +/- 2 (CPC), 2 +/- 2 (PC-2), and 3 +/- 2 (PC-8). CPC-R images were significantly better in overall image quality and number of vessels seen (P < .01). Mean S/Ns were 10.8 +/- 3.4 (CPC-R), 6.8 +/- 2.7 (CPC), 4.5 +/- 1.7 (PC-2), and 6.4 +/- 2.1 (PC-8). S/N with CPC-R was significantly greater than with CPC, PC-2, or PC-8.

CONCLUSION

CPC-R provided consistently higher quality angiographic images than were obtained with the other sequences studied.