Radiofrequency thermal ablation of hepatic tumors: pitfalls and challenges

Image-guided radiofrequency (RF) thermal ablation has been accepted as a promising interventional technique to control unresectable hepatic tumors. One important key to maximize the efficacy of RF ablation is to adhere to the therapeutic guidelines and to avoid preventable pitfalls. There are also several challenges obstructing successful ablation: poor approach path; small sonic window during multiple overlapping ablations; incomplete ablation due to the heat sink effect; subcapsular mass (too exophytic or the mass is adjacent to the gastrointestinal tract); focal residual tumors; too isoechoic or small masses; and mistargeting to adjacent another lesion. Knowledge of these challenges and pitfalls in RF ablation is helpful for a successful ablation.

Omental torsion: CT features

A 33-year-old male presented to the emergency department complaining of right upper quadrant pain and was initially diagnosed with acute cholecystitis. Abdominal computed tomography showed a whirling pattern of fatty streaks and vessels within the greater omentum, and surgery confirmed infarction of the omentum secondary to torsion. We report a case of surgically and pathologically proven omental torsion that demonstrated the typical whirling appearance on computed tomography.

Solid and papillary epithelial neoplasm of the pancreas with peritoneal metastasis and its recurrence: a case report

Solid and papillary epithelial neoplasm of the pancreas is a low-grade malignant tumor, generally occurring as a slowly growing upper abdominal mass in a young female. With complete excision, the prognosis is good. Malignant behavior with metastasis does occur, but the incidence is very low. We report a young woman who had this neoplasm in the pancreatic tail with peritoneal seeding and its recurrence.

Per-rectal contrast material for abdominal CT: usefulness of administration with an automatic injector

Adequate distention of the gastrointestinal tract is essential for the best quality image in abdominal computed tomography. We introduce a new technique for per-rectal administration of contrast material with the use of an automatic injector. With this technique, more contrast material can be inserted and thus adequately distend the colon, including the proximal colon.

Essential techniques for successful radio-frequency thermal ablation of malignant hepatic tumors

Radio-frequency thermal ablation is one of the most promising minimally invasive techniques for the treatment of nonresectable hepatic tumors. Essential technical tips to successful radio-frequency ablation therapy were collected from five international experts. They were organized into five categories: understanding the mechanisms and principles of radio-frequency ablation, modulation of tissue physiologic characteristics to increase tumor destruction, strategies of overlapping ablations, strategies to improve ablation according to tumor location, and imaging strategies after ablation to ensure adequate therapy. Established factors for optimal ablation, as well as emerging technical tips, are addressed with illustrations in each section. These essential tips will be very helpful for physicians performing radio-frequency ablation of hepatic tumors.

Conversion of gamma-butyrobetaine to L-carnitine by Achromobacter cycloclast

L-Carnitine is an ubiquitous substance that plays a major role in the transportation of long-chain fatty acids. We investigated crucial factors that influence microbial conversion of gamma-butyrobetaine to L-carnitine using an Achromobacter cycloclast strain. Two-stage culture results showed that gamma-butyrobetaine induced enzymes essential for the conversion, which suggests that the precursor should be present in the initial cell growth stage. The addition of yeast extract enhanced L-carnitine production whereas inorganic nitrogen sources inhibited it. Under nitrogen-limiting conditions, the cells accumulated poly-beta-hydroxybutyrate instead of L-carnitine. Among the trace elements tested, nickel addition enhanced L-carnitine production by almost twice that of the control and copper strongly inhibited the conversion. L-Carnitine production was reduced when the medium contained inorganic salts of sodium, potassium, and calcium at a concentration greater than 2 g l(-1). A higher L-carnitine yield was achieved when cells were incubated in a lower culture volume. The optimal pH for L-carnitine production was 5 to 5.5, whereas that of growth was 7.0, indicating that a pH shift was required. Under optimal conditions, L-carnitine concentrations as high as 15 g l(-1) were obtained in 62 h with a 45% molar conversion yield.

Peripheral cholangiocarcinoma with extensive tumor thrombi in the portal venous system: case report

Peripheral cholangiocarcinoma is a primary liver tumor, with some features that distinguish it from hepatocellular carcinoma, especially the low incidence of vascular involvement relative to mass size. Radiologically, tumor thrombus seen as an expanding central filling defect is a rare finding of cholangiocarcinoma on computed tomography, even though microscopic invasion or vascular encasement has been reported in a few studies. We report a case of a peripheral cholangiocarcinoma with tumor thrombus expanding and spreading from the portal vein to the superior mesenteric vein.

Radiologic findings of renal hemangioma: report of three cases

Renal hemangioma is an uncommon benign tumor which usually causes painless or painful gross hematuria. Its preoperative diagnosis is extremely difficult or even impossible. We experienced three cases of renal hemangioma, located mainly at the pelvocalyceal junction or in the inner medulla. US demonstrated variable echogenecity, and CT revealed a lack of significant enhancement. Where there is gross hematuria in a young adult, especially when the renal mass located in the pelvocalyceal junction or inner medulla shows little enhancement on CT, renal hemangioma should form part of the differential diagnosis.

Brenner tumor of the ovary: CT and MR findings

PURPOSE

The purpose of this study was to determine the CT and MR characteristics of Brenner tumors, rare epithelial neoplasms of the ovary.

METHOD

CT and MR scans of eight pathologically proven Brenner tumors of the ovary (seven benign, one malignant, and one associated with mucinous cystadenoma) were retrospectively reviewed. The masses were analyzed for location, size, external configuration, internal architecture, enhancement pattern, presence of calcification, and metastatic spread.

RESULTS

The patients' median age was 63 years (range 39-79 years), and the mean size of the tumors was 11.4 cm (7.5-17 cm). All tumors were unilateral and had a well-defined margin. The mass was mostly solid in three, mostly cystic in one, and "mixed" solid and cystic in four cases. The tumors with cystic components (n = 5) were mostly multilocular in appearance (n = 4). All the solid components showed mild homogeneous enhancement on postcontrast CT and MRI. Extensive amorphous calcification within the solid component on CT was seen in five of six cases (83%). No characteristic findings discriminating malignancy from benign Brenner tumor could be found.

CONCLUSION

Extensive amorphous calcification in a solid mass or solid component in a multilocular cystic mass is a characteristic finding of Brenner tumor of the ovary on CT and MRI.

Postadministration of oral contrast material for abdominal CT in patients with gastrectomy: modified drip ingestion method

We introduce the modified drip ingestion method (MDIM) of administering oral contrast material for abdominal computed tomography (CT) in patients after gastrectomy. MDIM consists of the drip ingestion method, which we have recently reported, with additional ingestion of effervescent agent. MDIM in abdominal CT is a useful technique to improve the degree of distention of the gastrointestinal lumen including anastomotic sites in patients after gastrectomy.

MR imaging of primary uterine lymphoma

Primary malignant lymphoma of the uterus is a rare disease. We present the MR findings in three cases where the uterus was the initial site. MR findings wer retrospectively evaluated. Although the intact junctional zone is a specific finding for lymphoma, diffuse enlargement of the uterus and relatively homogeneous signal intensity on MR imaging in spite of large tumor size are helpful for diagnosing uterine lymphoma.

CT scan as an important diagnostic tool in the initial phase of diffuse bilateral renal cortical necrosis

The serious clinical circumstances and coagulopathy generally accompanied by diffuse bilateral renal cortical necrosis (BRCN), especially during the early period, do not allow renal biopsy being well known as a gold standard diagnostic method for BRCN. Therefore, other noninvasive diagnostic modalities in the initial phase of BRCN have been tried, and, among them, contrast-enhanced computerized tomography (CT) was found to provide very characteristic representative findings, i.e., low attenuation of cortex sparing thin rim of subcapsular cortex and medulla, correlating well with histological findings of renal biopsy performed in the late somewhat stable clinical status or at autopsy. These specific CT findings were reported consistently with or without renal biopsy in several articles recently. Herein, we present a 38-year-old woman of massive automobile accident victim, developed protracted total anuria as well as shock with disseminated intrasvascular coagulation (DIC), and diagnosed as BRCN by the specific CT findings without renal biopsy in the second day of admission. Simultaneously, all the scattered cases of BRCN diagnosed by CT are reviewed and contrast to the findings of other diagnostic procedures performed for the same cases. The importance of contrast-enhanced CT as noninvasive diagnostic procedure during the initial phase of BRCN is stressed.

Systemic lupus erythematosus with obstructive uropathy. Case report and review

We report a case of patient with documented SLE who displayed dysuria, gastrointestinal (GI) symptoms and renal insufficiency associated with the unusual occurrence of bilateral hydroureteronephrosis due to urterovesical junction stricture (obstructive uropathy). Pathologic investigations disclosed chronic interstitial cystitis (IC) with evidence of focal immune complex deposition in the blood vessel walls of the bladder. The GI symptoms and dysuria regressed with initial therapy for SLE with steroids. However, the persistent obstructive uropathy (OU) and renal insufficiency required bilateral nephrostomy followed by steroids plus intravenous pulse injection of cyclophosphamide. The obstructive uropathy was relieved even after removing the nephrostomy tube and renal function remained stable. Including this case, nineteen SLE patients associated with clinical and radiographic findings of OU were found in the world literature and reviewed to find any consistent pattern of clinical features. Most of the patients with OU in SLE were female (mean age, 31.7 yr) and orientals (63%), and had interstitial cystitis (89%) as a common underlying cause with concomitant involvement of the GI tract (89%) and WHO class IV or V advanced glomerulonephritis (67%). Despite the remarkable response (68%) to steroids in majority of OU patients associated with SLE, certain patients still required surgical correction (32%) and some even died (32%). OU, potentially reversible, was not an exception in patients with SLE, which might be overshadowed by other major organ involvement of SLE.

Acinar cell carcinoma of the pancreas. Ultrasonography and computed tomography findings

The radiologic findings in two cases of acinar cell carcinoma of the pancreas are described. Sonographic findings were a midrange echogenic mass with heterogeneity, containing some small- and medium-sized low echogenic areas suggesting necrosis. Ultrasonic through-transmission was good. Computed tomography findings were a well-defined, hypodense, large mass having an enhancing, thin capsule. There were multiple small- and medium-sized irregular low-density areas suggesting necrosis. Small punctate calcific foci were present in one case. With these characteristics, acinar cell carcinoma can be distinguished from the locally invasive common adenocarcinoma of the pancreas, but the differentiation from some other less common pancreatic tumors remains difficult.